Everything you need to know about Computed Tomography (CT) & CT Scanning

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July 2017 Imaging Pearls - Learning Modules | CT Scanning | CT Imaging | CT Scan Protocols - CTisus
Imaging Pearls ❯ July 2017
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3D and Workflow

    • PURPOSE: The present study aimed to compare the reliability of interpreting CT scans viewed by orthopedic surgeons in two ways for diagnosing, classifying, and treatment planning for thoracolumbar spine fractures: (1) captured as video clips from standard workstation-based picture archiving and communication system (PACS) and sent via a smartphone-based instant messaging application for viewing on a smartphone; and (2) viewed directly on a PACS.


      METHODS: CT scans were captured by use of an iPhone 6 smartphone from a computer screen displaying PACS. Then by use of the WhatsApp instant messaging application, video clips of the scans were sent to the personal smartphones of five spine surgeons. These evaluators were asked to diagnose, classify, and determine the course of treatment for each case. Evaluation of the cases was repeated 4 weeks later, this time using the standard method of workstation-based PACS. Intraobserver agreement was interpreted based on the value of Cohen's kappa statistic.
    • CONCLUSIONS: Video clips of CT scans can be readily captured by a smartphone from a workstation-based PACS and then transmitted by use of the WhatsApp instant messaging application. Diagnosing, classifying, and proposing treatment of fractures of the thoracic and lumbar spine can be made with equal reliability by evaluating video clips of CT scans transmitted to a smartphone or by the standard method of viewing the CT scan on a workstation-based PACS. Evaluating video clips of CT scans transmitted to a smartphone is a readily accessible, simple, and inexpensive method. We believe that it can be reliably used for consultations between the emergency physicians or orthopedic or neurosurgical residents with offsite, on-call specialists. It might also enable rural orcommunity emergency department physicians to communicate more efficiently and effectively with surgeons in tertiary referral centers.
    • CONCLUSIONS: Diagnosing, classifying, and proposing treatment of fractures of the thoracic and lumbar spine can be made with equal reliability by evaluating video clips of CT scans transmitted to a smartphone or by the standard method of viewing the CT scan on a workstation-based PACS. Evaluating video clips of CT scans transmitted to a smartphone is a readily accessible, simple, and inexpensive method. We believe that it can be reliably used for consultations between the emergency physicians or orthopedic or neurosurgical residents with offsite, on-call specialists. It might also enable rural orcommunity emergency department physicians to communicate more efficiently and effectively with surgeons in tertiary referral centers.
Reliability of smartphone-based teleradiology for evaluating thoracolumbar spine fractures

      
Stahl I et al.
Spine J. 2016 Aug 16. pii: S1529-9430(16)30882-8.
    • “The visual and tactile inspection of 3D models allowed the best anatomical understanding, with faster and clearer comprehension of the surgical anatomy. As expected, less experienced medical students perceived the highest benefit (53.9% ± 4.14 of correct answers with 3D-printed models, compared to 53.4 % ± 4.6 with virtual models and 45.5% ± 4.6 with MDCT), followed by surgeons and radiologists. The average time spent by participants in 3D model assessing was shorter (60.67 ± 25.5 s) than the one of the corresponding virtual 3D reconstruction (70.8 ± 28.18 s) or conventional MDCT scan (127.04 ± 35.91 s).”
Value of 3D printing for the comprehension of surgical anatomy.


      Marconi S et al.
Surg Endosc. 2017 Mar 9. doi: 10.1007/s00464-017-5457-5. [Epub ahead of print]


    • What is 3D printing?

      3D printing, also known as additive manufacturing (AM), refers to processes used to create a three-dimensional object  in which layers of material are formed under computer control to create an object. Objects can be of almost any shape or geometry and are produced using digital model data from a 3D model or another electronic data source such as an Additive Manufacturing File (AMF) file.
    • What has been the early use of 3D Printing in Medicine?
      • Physician education and training
      • Patient education and communication
      • Custom design of prosthesis
      • Surgical simulation and rehearsal
      • Medical devise prototyping
    • RESULTS: Accurate life-sized 3D cardiac prototypes were successfully created for all patients. The models enabled radically improved 3D understanding of anatomy, identification of specific technical challenges, and precise surgical planning. Augmentation of existing clinical and imaging data by 3D prototypes allowed successful execution of complex surgeries for all five patients, in accordance with the preoperative planning.

      CONCLUSIONS: 3D-printed cardiac prototypes can radically assist decision-making, planning, and safe execution of complex congenital heart surgery by improving understanding of 3D anatomy and allowing anticipation of technical challenges
Three-dimensional-printed cardiac prototypes aid surgical decision-making and preoperative planning in selected cases of complex congenital heart diseases: Early experience and proof of concept in a resource-limited environment.


      Kappanayil M et al.
Ann Pediatr Cardiol. 2017 May-Aug;10(2):117-125.

    • BACKGROUND: Rapid growth of three-dimensional (3D) printing in recent years has led to new applications of this technology across all medical fields. This review article presents a broad range of examples on how 3D printing is facilitating liver surgery, including models for preoperative planning, education, and simulation.


      CONCLUSIONS: Although the technology is still in its early stages, presented models are considered useful in preoperative planning and patient and student education. There are multiple factors limiting the use of 3D printing in everyday healthcare, the most important being high costs and the time-consuming process of development. Promising early results need to be verified in larger randomized trials, which will provide more statistically significant results.


      3D Printing in Liver Surgery: A Systematic Review.
Witowski JS et al.
Telemed J E Health. 2017 May 22. doi: 10.1089/tmj.2017.0049. [Epub ahead of print]
    • PURPOSE: Three-dimensional (3D) printing for preoperative planning has been intensively developed in the recent years. However, the implementation of these solutions in hospitals is still difficult due to high costs, extremely expensive industrial-grade printers, and software that is difficult to obtain and learn along with a lack of a defined process. This paper presents a cost-effective technique of preparing 3D-printed liver models that preserves the shape and all of the structures, including the vessels and the tumor, which in the present case is colorectal liver metastasis.


      CONCLUSIONS: The increased accessibility of 3D models for physicians before complex laparoscopic surgical procedures such as hepatic resections could lead to beneficial breakthroughs in these sophisticated surgeries, as many reports show that these models reduce operative time and improve short term outcomes.
Cost-effective, personalized, 3D-printed liver model for preoperative planning before laparoscopic liver hemihepatectomy for colorectal cancer metastases.


      Witowski JS et al.
Int J Comput Assist Radiol Surg. 2017 Jan 31. doi: 10.1007/s11548-017-1527-3. [Epub ahead of print]
    • “This study aims to examine the educational value of the 3DP model from the learner's point of view. Students (n = 15) compared the developed 3DP models with the plastinated prosections, and provided their views on their learning experience using 3DP models using a survey and focus group discussion. Anatomical features in 3DP models were rated as accurate by all students. Several positive aspects of 3DP models were highlighted, such as the color coding by tissue type, flexibility and that less care was needed in the handling and examination of the specimen than plastinated specimens which facilitated the appreciation of relations between the anatomical structures.”


      Evaluation by medical students of the educational value of multi-material and multi-colored three-dimensional printed models of the upper limb for anatomical education.
Mogali SR et al.
Anat Sci Educ. 2017 May 19. doi: 10.1002/ase.1703. [Epub ahead of print]
    • “The authors identified the need for an educational aid when teaching acetabular fracture classifications, given the complex spatial anatomy and the nonintuitive classification system that is commonly used. Three-dimensional (3D) printing is an evolving technique that has applications as an educational aid, providing the student with a tangible object to interact with and learn from.”


      Creating Three-dimensional Printed Models of Acetabular Fractures for Use as Educational Tools
Matthew S. Manganaro, Yoav Morag, William J. Weadock, Corrie M. Yablon, Kara Gaetke-Udager, and Erica B. Stein
RadioGraphics 2017 37:3, 871-880 
    • “Printing was performed by using an additive manufacturing principle, with approximately 36–48 hours needed for printing, postprocessing, and drying.The cost to print a 1:1 scale model was approximately $100–$200, depending on the amount of plastic material used.These models can then be painted according to the two-column theory regarding acetabular fractures.”
Creating Three-dimensional Printed Models of Acetabular Fractures for Use as Educational Tools
Matthew S. Manganaro, Yoav Morag, William J. Weadock, Corrie M. Yablon, Kara Gaetke-Udager, and Erica B. Stein
RadioGraphics 2017 37:3, 871-880 
    • “Three-dimensional models that enhance our understanding of common diagnostically challenging issues encountered in routine clinical practice and that facilitate improved diagnosis and treatments are likely to yield the greatest educational benefits. Rarely encountered variants and pathologic entities may not be suitable for 3D model projects; however, a model that depicts a unique abnormality may be useful for patient education.”


      Creating Three-dimensional Printed Models of Acetabular Fractures for Use as Educational Tools
Matthew S. Manganaro, Yoav Morag, William J. Weadock, Corrie M. Yablon, Kara Gaetke-Udager, and Erica B. Stein
RadioGraphics 2017 37:3, 871-880 
    • “The visual and tactile inspection of 3D models allowed the best anatomical understanding, with faster and clearer comprehension of the surgical anatomy. As expected, less experienced medical students perceived the highest benefit (53.9% ± 4.14 of correct answers with 3D-printed models, compared to 53.4 % ± 4.6 with virtual models and 45.5% ± 4.6 with MDCT), followed by surgeons and radiologists. The average time spent by participants in 3D model assessing was shorter (60.67 ± 25.5 s) than the one of the corresponding virtual 3D reconstruction (70.8 ± 28.18 s) or conventional MDCT scan (127.04 ± 35.91 s).”

      
Value of 3D printing for the comprehension of surgical anatomy.
Marconi S et al.
Surg Endosc. 2017 Mar 9. doi: 10.1007/s00464-017-5457-5. [Epub ahead of print]

    • “Newly developed 3D printing technologies can recreate patient-specific anatomy, but the stiffness of the materials limits delity to real-life surgical situations. Hollywood special effects techniques can create ultrarealistic features, including lifelike tactile properties, to enhance accuracy and effectiveness of the surgical models.”


      Creation of a novel simulator for minimally invasive neurosurgery: fusion of 3D printing and special effects
Weinstock P et al.
J Neurosurg Pediatr April 25, 2017 (in press)

    • “A plug-and-play lifelike ETV training model was developed through a combination of 3D printing and special effects techniques, providing both anatomical and haptic accuracy. Such simulators offer opportunities to accelerate the development of expertise with respect to new and novel procedures as well as iterate new surgical approaches and innovations, thus allowing novice neurosurgeons to gain valuable experience in surgical techniques without exposing patients to risk of harm.”


      Creation of a novel simulator for minimally invasive neurosurgery: fusion of 3D printing and special effects
Weinstock P et al.
J Neurosurg Pediatr April 25, 2017 (in press)

    • What does it take to get started with 3D Printing?
      • Consider a focused question and start there
      • Do you need to buy a printer and if so how much will it cost?
      • Who pays for the 3D models? (patient, insurance, research funds)
      • What’s the turnaround time for the studies and what turnaround tie do you need?
Adrenal

    • “Pheochromocytomas tend to have different CT imaging features mimicking other tumors according to the size of the tumors. However, clinical features, CT imaging characteristics, and radioisotope activity are not different between small and large pheochromocytomas.”

      
Assessment of clinical and radiologic differences between small and large adrenal pheochromocytomas.
Kim DW et al.
Clin Imaging. 2017 May - Jun;43:153-157
Colon

    • “The most frequent complication of DD is diverticulitis, and the second one is hemorrhage. Excluding ano-rectal diseases, hemorrhage secondary to DD is the second cause of bleeding of the lower gastrointestinal tract, but it is the main cause of massive bleeding up to 30 to 50% of cases. It is estimated that up to 15% of patients with DD in the colon will bleed at some point in their life, bleeding is usually painless and large, and is up to one-third of the cases massive and requires hospitalization and transfusion support.” 


      Colonic diverticular bleeding. Have we identified the risk factors for massive bleeding yet?
Blancas Valencia JM
 Rev Esp Enferm Dig. 2017 Jan;109(1):1-2.
    • “It is estimated that up to 15% of patients with DD in the colon will bleed at some point in their life, bleeding is usually painless and large, and is up to one-third of the cases massive and requires hospitalization and transfusion support.” 
 Colonic diverticular bleeding. Have we identified the risk factors for massive bleeding yet?
Blancas Valencia JM
 Rev Esp Enferm Dig. 2017 Jan;109(1):1-2.
    • “The natural history of colonic diverticula hemorrhage indicates that it is stopped spontaneously in 70 to 80% of cases, so treatment should be directed to support management, in 20 to 30% of cases specific medical treatment through endoscopic management with any of the available modalities such as: epinephrine injection, thermal or mechanical methods such as endoscopic clip or ligature, and in very few cases a radiological or surgical treatment will be necessary.” 


      Colonic diverticular bleeding. Have we identified the risk factors for massive bleeding yet?
Blancas Valencia JM
 Rev Esp Enferm Dig. 2017 Jan;109(1):1-2.
    • “Once the initial episode of bleeding stops, most patients will not recur, and only 30% will present a second bleeding episode and in this rebleeding group the risk of a new bleeding episode is very high, so surgical treatment is recommended.” 


      Colonic diverticular bleeding. Have we identified the risk factors for massive bleeding yet?
Blancas Valencia JM
 Rev Esp Enferm Dig. 2017 Jan;109(1):1-2.
    • Colonic Diverticular Bleeding: Risk Factors
      • smoking
      • alcohol consumption
      • consumption of non-steroidal anti-inflammatory drugs (NSAIDs)
      • antithrombotic drugs
      • bilateral presence of colonic DD
      • chronic degenerative diseases, such as hypertension, diabetes mellitus, ischemic heart disease and obesity
Kidney

    • Renal Artery Stenosis
      • Role of revascularization vs medical therapy for atherosclerotic renal artery stenosis remains controversial
      • Restenosis rate is lower in renal arteries than coronary arteries
      • Emboli into renal vascular bed and elsewhere remains a major concern
    • RAS: Benefits of Stenting
      • improves hypertension
      • stabilizes renal failure
      • reduces recurrent cardiac events such as flash pulmonary edema
    • Fibromuscular Dysplasia
      • medial fibroplasia
      • perimedial fibroplasia
      • medial hyperplasia
      • medial dissection
      • intimal fibroplasia
      • adventitial fibroplasia
      • medial fibroplasia- mid to distal RA
      • perimedial fibroplasia
      • medial hyperplasia
      • medial dissection
      • intimal fibroplasia
      • adventitial fibroplasia
      • “string-of-beads”
         - beading is larger than normal artery diameter
      • focal, concentric stenos(es)
      • smooth, long stenosis
      • aneurysm(s)
      • dissection
         - intimal and periarterial FMD
      • thrombosis
         - intimal and periarterial FMD
    • Renal Artery Stenosis
      • Majority of renal artery stenosis (90%) is due to atherosclerosis.
      • Risk factors
         - age
         - diabetes
         - aortoiliac occlusive disease
         - hypertension
         - coronary artery disease
    • Fibromuscular Dysplasia: Facts
      • FMD causes less than 10% of renal artery stenosis
      • young or middle aged women
      • associations:
         - smoking
         - hormones
         - vasa vasorum disorders
      • In symptomatic patients, lesions are bilateral in 71%
    • Renal Artery Aneurysm
      • hypertension
      • systemic atherosclerosis
      • extrarenal aneurysms
      • FMD
      • arteritis
      • dissection
      • smoking
      • Marfan syndrome
      • Ehlers-Danlos syndrome
      • Neurofibromatosis
      • aortic coarctation
      • infectious etiologies
    • Renal Artery Aneurysms : Repair
      • All aneurysms > 2 cm
      • Most renal artery aneurysms 1.5 to 2 cm
      • RAA> 1 cm in conjunction with risk factors
         - hypertension
         - ipsi or contralateral renal artery stenosis
         - women of childbearing age
    • Renal Artery Thrombosis: CT Findings
      Axial image from arterial phase CT
      • Elongated filling defect in right renal artery
      • Sharply demarcated cortical hypoenhancement in right kidney secondary to infarct
      • Infarcts are subtle on early CT
    • Renal Artery Stenosis
      • Describe locations
         - atherosclerotic lesions usually arise in the proximal 2 cm or proximal 1/3 of the artery
      • Grade stenosis
      • Characterization of plaque
         - atherosclerotic lesions often calcified
      • Delineation of any secondary findings
    • Renal Artery Aneurysms
      • Usually incidental
      • May be symptomatic pain, hematuria
      • 60% at main artery bifurcation or mainstem artery
      • Bilateral in 19%
      • Multiple in 25-33%
      • ~1/3 of patients have ipsilateral renal artery stenosis
    • Renal Artery Aneurysms : Complications
      • hypertension
      • rupture
      • RA thrombosis
      • infarction by distal embolization
      • AV fistula
    • Renal Artery Aneurysms : Complications
      • Some recommend repair in the setting of pain, or complications, such as dissection or embolization.
      • Endovascular repair has become an alternative treatment option
      • CT can be used to confirm patency following stent-graft occlusion
    • Renal Artery Aneurysms : Complications
      • Risk of rupture increases during pregnancy and correlates with aneurysm size.
      • Surgical treatment
         - decreased blood pressure in 47-60% of those with preoperative hypertension
         - renal function may be improved
    • Renal Artery Dissection
      • Extension from an abdominal aortic dissection
      • Trauma (blunt or iatrogenic)
      • FMD
      • Anti-phospholipid antibody association
      • Ehlers Danlos
      • Idiopathic
    • Renal Artery Thrombosis
      • Thromboembolic disease- cardiac most common
      • Renal Artery insult
         - Spontaneous/traumatic dissection
         - Fibromuscular dysplasia (FMD)
      • Hypercoaguability
         - Antiphospholipid Syndrome
         - Nephrotic Syndrome
    • Renal AVM
      • Rare, congenital malformation
      • May be large (aneurysmal) and solitary or numerous and small (cirsoid type).
         - Cirsoid type more common. 
      • Usually located in renal sinus
      • Usually solitary and right sided
    • Renal AVM: Presentation
      • gross hematuria
      • hypertension
      • flank pain
      • high cardiac output failure
    • Renal Cell Carcinoma: Statistics
    • Survival Data 2017
    • Renal Cell Carcinoma: By the Numbers
    • Age Range for Renal Cell Carcinoma
    • Frequency of RCC
Small Bowel

    • SMA Thrombosis: Causes
      • Embolic
      • Progression of atherosclerosis
      • Trauma
      • Infection
      • Spontaneous
    • SMA Occlusion
      Embolism (57%) > thrombosis
      • half of patients with SMA embolus have cardiac thrombus
      • 40% have atrial fibrillation
      • occlusion more likely to be distally located in the SMA
      • synchronous emboli in other locations in 68%
      Thrombotic occlusion
      • more extensive intestinal infarction
    • Mesenteric Artery Stenosis
      • Atherosclerosis in older patients
      • Median arcuate ligament syndrome
         - younger patients
      • Other causes
         - tumor encasement (pancreatic cancer)
         - pancreatitis
         - vasculitis
    • Mesenteric Ischemia
      • Chronic mesenteric ischemia is caused by occlusive disease of mesenteric vessels
      • Most often due to atheroma
      • Women > men
      • Patients >60 years
      • Severe stenosis (often multivessel) manifests with abdominal pain or other nonspecific symptoms
    • Chronic Mesenteric Ischemia
      • Takayasu disease
      • fibromuscular dysplasia
      • thromboangiitis obliterans
      • periarteritis nodosum
      • radiation therapy
      • median arcuate ligament syndrome
    • Median Arcuate Ligament Syndrome
      • Median arcuate ligament runs obliquely between the diaphragmatic crura
      • Low lying ligament can compress celiac artery
      • Various degrees of narrowing and obstruction
      • Median Arcuate Ligament “Syndrome” if patient symptomatic
    • Visceral Arterial Aneurysms
      • splenic artery in 60%–80% of cases
      • hepatic artery in 20%
      • SMA in 5.5%
      • celiac artery in 4%
      • gastric and gastroepiploic artery in 4%,
      • GDA, pancreatic branches in 6%
      • jejunal and ileocolic arteries in 3%
      • IMA in less than 1%
    • Splenic Artery Aneurysms
      • Small and asymptomatic- serial imaging
      • Surgical intervention at 2 cm
      • More aggressive management may be warranted in high risk clinical settings
         - women of childbearing age
         - cirrhotics
    • Celiac Artery Aneurysms
      • Post-stenotic dilatation w/proximal stenosis
      • Atherosclerosis
      • Focal dissection
      • Medial degeneration
      • Genetic syndrome: Ehlers Danlos
    • Celiac Artery Aneurysms
      Rupture or impending rupture are made apparent by signs and symptoms
      • pain
      • gastrointestinal bleeding
      Size threshold for surgical repair of celiac artery aneurysms 2 cm in surgical candidates
    • Visceral Arterial Aneurysms
      • Treatment options include surgical vs endovascular approaches based on location
      • For many cases, ligation or coil embolization is the treatment of choice
      • Stents are used primarily in cases of aneurysms of major branches, where preservation of arterial flow is required
    • Pseudoaneurysms
      • Nearly always present with symptoms
      • Only 2.5% of cases presented incidentally
      • Untreated mortality rate approaches 90%
      • Small and large aneurysms can rupture
      • Emergent coil embolization
    • Mesenteric Artery Dissection
      • Isolated celiac or SMA dissection
      • Exclusive of aortic dissection
      • 10% of patients celiac and SMA involved
      • May present acutely w/ abdominal pain
      • Often incidentally identified on CT
      • typically stable without complication
    • Mesenteric Artery Dissection
      • atherosclerosis
      • vasculitis
      • connective tissue disorder
      • Type IV Ehlers-Danlos
      • Trauma
      • fibromuscular dysplasia
      • cystic medial necrosis
      • Hypertension
      • Systemic arterial mediolysis
    • Segmental Arterial Mediolysis
      • Rare noninflammatory vasculopathy
      • Medial layer disrupted
      • Dissection, hemorrhage, ischemia
      • Visceral and mesenteric arteries most common
      • Abdominal pain, GI bleeding
    • Segmental Arterial Mediolysis: CT
      • String of beads
      • Stenoses
      • Aneurysms
      • Dissection
      • Thrombosis
    • SAM: Differential Dx
      • FMD
      • PAN
      • ANCA assoc vaculitis
      • Giant cell arteritis
      • Takayasus
      • Bechets
      • Type IV EDS
    • Superior Mesenteric Artery Syndrome
      • Obstruction of the third portion of the duodenum between the SMA and aorta
      • Cast syndrome, Wilke syndrome
      • Arteriomesenteric duodenal compression syndrome
    • SMAS: CT Criteria
      • Aortomesenteric angle
         - Normally 28 to 65 degrees
         - Reduced to < 22 degrees in SMAS
      • Aortomesenteric distance
         - Normally 10-34 mm
         - Less than 8 mm in SMAS
      • Dilated duodenum and stomach proximal
      • Obstructed left renal vein (“nutcracker”)
    • “All patterns of enhancement on contrast enhanced computed tomography (CECT) can be seen with GISTs, including hypoenhancing, isoenhancing, and hyperenhancing tumors. They can be large or small, endoluminal or exophytic. Clinical presentations include asymptomatic patients, nonspecific symptoms, obstruction, and bleeding. Bleeding can take the form of slow, intraluminal GI bleeding or massive intraperitoneal bleeding secondary to rupture and can be seen regardless of the enhancement pattern.”
 Getting the GIST: a pictorial review of the various patterns of presentation of gastrointestinal stromal tumors on imaging.


      Scola D et al.
Abdom Radiol 2017 May;42(5):1350-1364.
    • “The vast majority of GISTs are sporadic. Although rare, they can present in association with genetic syndromes including neurofibromatosis 1; Carney-Stratakis Syndrome, characterized by gastric GIST and paraganglioma; Carney Triad Syndrome which consists of (i) gastric GIST, (ii) pulmonary chondroma, and (iii) paraganglioma; and familial GIST syndrome.”


      Getting the GIST: a pictorial review of the various patterns of presentation of gastrointestinal stromal tumors on imaging.
Scola D et al.
Abdom Radiol 2017 May;42(5):1350-1364.
    • “GISTs are the most common form of sarcoma, and as such no GIST can truly be classified as benign. Most patients have localized disease (79.4%), but approximately 11.4% have regional/distant metastatic disease at the time of presentation. Recurrences have been reported up to 30 years after initial diagnosis and resection. Metastasis during initial presentation or after resection more commonly involve the liver and peritoneal surfaces due to GISTs tendency for local invasion.”


      Getting the GIST: a pictorial review of the various patterns of presentation of gastrointestinal stromal tumors on imaging.
Scola D et al.
Abdom Radiol 2017 May;42(5):1350-1364.

    • Getting the GIST: a pictorial review of the various patterns of presentation of gastrointestinal stromal tumors on imaging.
Scola D et al.
Abdom Radiol 2017 May;42(5):1350-1364
    • GIST Tumors: Site of Origin
      • stomach (approximately 60%)
      • jejunum/ileum (30%)
      • duodenum (5%)
      • colon (4%)
      • esophagus or appendix (1%) 
    • “Clinical presentations are highly variable and usually dependent on tumor size and location. Exophytic lesions are often large at the time of presentation, while smaller lesions that erode through the mucosa and result in mucosal ulceration can present earlier with GI bleeding. If visualized on endoscopy (stomach and duodenum) they can be mistaken for ulcers. If located in the distal small bowel, GISTs commonly present later as large cavitary masses. Often, patients are asymptomatic until the tumor reaches a large size. The most common symptoms are usually nonspecific, including abdominal pain, nausea, weight loss, or obstruction. Occasionally, patients may present with GI bleeding, which may be occult or take the form of frank hemorrhage with hemodynamic instability. Likewise, tumors can rupture on the external surface, causing intraperitoneal hemorrhage which can be life threatening.”


      Getting the GIST: a pictorial review of the various patterns of presentation of gastrointestinal stromal tumors on imaging.
Scola D et al.
Abdom Radiol 2017 My;42(5):1350-1364.
    • “Clinical presentations are highly variable and usually dependent on tumor size and location. Exophytic lesions are often large at the time of presentation, while smaller lesions that erode through the mucosa and result in mucosal ulceration can present earlier with GI bleeding. The most common symptoms are usually nonspecific, including abdominal pain, nausea, weight loss, or obstruction. Occasionally, patients may present with GI bleeding, which may be occult or take the form of frank hemorrhage with hemodynamic instability. Likewise, tumors can rupture on the external surface, causing intraperitoneal hemorrhage which can be life threatening.”


      Getting the GIST: a pictorial review of the various patterns of presentation of gastrointestinal stromal tumors on imaging.
Scola D et al.
Abdom Radiol 2017 My;42(5):1350-1364.
    • CTA Abdomen for GI Bleeding: Facts
      • Can detect bleeding rates as slow as 0.3 mL/min, compared with 0.5 to 1.0 mL/min for conventional angiography and 0.2 mL/min for Tc-99m-labeled RBC scintigraphy 
      • CTA may be positive when other techniques are negative including endoscopy and GI Bleeding studies
      • Pooled sensitivity of 85% in diagnosing GI in the GI tract and may see intraluminal blood even if bleeding site is not seen
    • Upper GI Bleeding (UGIB): Facts
      • Occurs proximal to the ligament of Treitz, originating from the esophagus, stomach, or duodenum
      • UGIB will present with hematemesis or melena, but UGIB can also result in hematochezia
      • Overt GI bleeding (GIB) refers to patients who present with melena or hematochezia with a source of bleeding that is identified.
      • Occult GIB is defined as patients who present with iron-deficiency anemia with or without guaiac-positive stools who are found to have a source of bleeding.
    • Upper GI Bleeding (UGIB): Etiology
      • The most common etiologies are;
      • duodenal ulcer
      • gastric erosions
      • gastric ulcer
      • varices
      • Mallory-Weiss tears
      • esophagitis,
      • duodenitis
      • neoplasm
    • ACR Appropriateness Criteria®Nonvariceal Upper Gastrointestinal Bleeding 

    • ACR Appropriateness Criteria®Nonvariceal Upper Gastrointestinal Bleeding 

    • ACR Appropriateness Criteria®Nonvariceal Upper Gastrointestinal Bleeding 

    • ACR Appropriateness Criteria®Nonvariceal Upper Gastrointestinal Bleeding
       
    • PURPOSE: To evaluate the negative predictive power of computed tomography angiography (CTA) for the identification of obscure acute gastrointestinal (GI) bleeding (GI bleeding not visualized/treated by endoscopy) on subsequent mesenteric angiography (MA) with the intention to treat.


      CONCLUSIONS: The high NPV of CTA for the evaluation of GI bleeding suggests utility for excluding patients that are unlikely to benefit from MA and subsequent endovascular therapy. CTA may be considered for the first line diagnostic study for the evaluation of obscure GI bleeding.
 No catheter angiography is needed in patients with an obscure acute gastrointestinal bleed and negative CTA.


      Shukla PA et al.
 Clin Imaging. 2017 May - Jun;43:106-109
    • PURPOSE: The diagnostic yield of computed tomography angiography (CTA) compared to digital subtraction angiography (DSA) for major obscure gastrointestinal bleeding (OGIB) is not known. Aim of the study was to prospectively evaluate the diagnostic yield of CTA versus DSA for the diagnosis of major OGIB.


      CONCLUSION: 
      Due to the lower invasiveness and higher diagnostic yield CTA should be favored over DSA for the diagnosis of major OGIB.
Computed tomography versus digital subtraction angiography for the diagnosis of obscure gastrointestinal bleeding


      Wildgruber M, Wrede CE, Zorger N, et al.
 Eur J Radiol. 2017 Mar;88:8-14.
    • OBJECTIVE: Lower gastrointestinal hemorrhage is a common cause of hospitalization and has substantial associated morbidity and financial cost. CT angiography (CTA) is emerging as an alternative to (99m)Tc-labeled RBC scintigraphy (RBC scintigraphy) for the localization of acute lower gastrointestinal bleeding (LGIB); however, data on comparative efficacy are scant. The aim of this study was to assess the utility of CTA compared with RBC scintigraphy in the overall evaluation and management of acute LGIB.


      CONCLUSION: Both CTA and RBC scintigraphy can be used to identify active bleeding in 38% of cases. However, the site of bleeding is localized with CTA in a significantly higher proportion of studies.
 Localizing Acute Lower Gastrointestinal Hemorrhage: CT Angiography Versus Tagged RBC Scintigraphy.
Feuerstein JD et al.
 AJR Am J Roentgenol. 2016 Sep;207(3):578-84 

    • “Several studies have shown high sensitivity of CTA in detecting the source and localizing the site of LGIB , including identification of nonbleeding intestinal and vascular lesions , and the results suggest an advantage over RBC scintigraphy.”


      Localizing Acute Lower Gastrointestinal Hemorrhage: CT Angiography Versus Tagged RBC Scintigraphy.
Feuerstein JD et al.
 AJR Am J Roentgenol. 2016 Sep;207(3):578-84
    • RESULTS: 24 consecutive patients (11 men; median age 64 years) were included. CTA and DSA identified an active bleeding or a potential bleeding lesion in 92% (22 of 24 patients; 95% CI 72%-99%) and 29% (7 of 24 patients; 95% CI 12%-49%) of patients, respectively (p<0.001). CTA and DSA identified an active bleeding in 42% (10 of 24; 95% CI 22%-63%) and 21% (5 of 24; 95% CI 7%-42%) of patients, respectively (p=0.06)
 Computed tomography versus digital subtraction angiography for the diagnosis of obscure gastrointestinal bleeding


      Wildgruber M, Wrede CE, Zorger N, et al.
 Eur J Radiol. 2017 Mar;88:8-14.
    • “The high NPV (negative predictive value) of CTA for the evaluation of GI bleeding suggests utility for excluding patients that are unlikely to benefit from MA (mesenteric angiography) and subsequent endovascular therapy. CTA may be considered for the first line diagnostic study for the evaluation of obscure GI bleeding.”


      No catheter angiography is needed in patients with an obscure acute gastrointestinal bleed and negative CTA.
Shukla PA et al.
Clin Imaging. 2017 May - Jun;43:106-109.

    • Lower GI Bleeding (LGIB): Causes
      • diverticular in origin (30–65%)
      • angiodysplasia (4–15%)
      • hemorrhoids (4–12%)
      • ischemic colitis (4–11%)
      • other colitis (3–15%)
      • neoplasia (2–11%)
      • post-polypectomy (2–7%)
      • rectal ulcer (0–8%)
      • rarer causes like Deulafoy lesions and rectal varices 
    • “On MDCTA, the extravasation of contrast material may demonstrate a linear, jet like, swirled or a pooled configuration. MDCTA provides a validated road map for ongoing invasive intervention for hemostasis in patients with positive blush, however a negative first CTA is a good predictor that patients presenting with LGIB will settle spontaneously not necessitating further intervention.”

      
Making decisions using radiology in lower GI hemorrhage
Zahid A, Young CJ
International Journal of Surgery
Volume 31, July 2016, Pages 100–103

    • “Multidetector CT Angiography (MDCTA) provides a first line diagnostic tool in the detection of the site of lower GI hemorrhage. As opposed to nuclear imaging techniques, MDCT allows for greater anatomical assessment of LGIB, allowing for planning of more invasive treatment. In the setting of acute LGIB, its sensitivity has been reported at 91–92%.”


      Making decisions using radiology in lower GI hemorrhage
Zahid A, Young CJ
International Journal of Surgery
Volume 31, July 2016, Pages 100–103

    • “Comparison was performed between patients who had positive and negative invasive MA (mesenteric angiogram) after a positive CTMA (CT mesenteric angiogram). Results Forty-eight invasive MA scans were performed in patients with LGIB following a positive CTMA scan. Twenty-three (47.9 %) were due to diverticular disease while 20 (41.7 %) bled from the small bowel. The median delay from a positive CTMA to invasive MAwas 144 (32–587)min. Of the 48 invasive MA, 25 demonstrated active extravasation. Invasive MA scans that was performed within 90 min after a positive CTMA scan were 8.56 (95 % CI 0.96–76.1, p=0.05) times more likely to detect a positive extravasation.”


      Does the timing of an invasive mesenteric angiography following a positive CT mesenteric angiography make a difference?
Koh FH et al.
Int. J. Colorectal Dis., 30 (1) (2014 Nov 4), pp. 57–61

    • “Preceding VA with a diagnostic study improves positive localization of the site of lower gastrointestinal hemorrhage compared with VA alone. Increasing the use of CTA for pre-angiography imaging may reduce overall imaging studies while appearing to increase positive yield at VA. Computed tomographic angiography can be used as part of a lower intestinal hemorrhage management algorithm and does not appear to worsen renal function despite the additional contrast load.”


      Arteriography for Lower Gastrointestinal Hemorrhage: Role of Preceding Abdominal ComputedTomographic Angiogram in Diagnosis and Localization.
Jacovides CL et al.
 JAMA Surg 2015 Jul;150(7):650-6.
    • “Although nuclear scintigraphy and CTA had similar sensitivity and specificity, localization of hemorrhage site by CTA was more precise and consistent with angiography findings. As a pre-angiography test, compared with nuclear scintigraphy, CTA reduced overall the number of imaging studies required (mean [SD] number per patient admission, 2.1 [0.3] vs 2.5 [0.8]; P = .005) and resulted in administration of more overall contrast (mean [SD], 220 [80] vs 130 [70] mL; P < .001) without worsening renal function.”


      Arteriography for Lower Gastrointestinal Hemorrhage: Role of Preceding Abdominal ComputedTomographic Angiogram in Diagnosis and Localization.
Jacovides CL et al.
 JAMA Surg 2015 Jul;150(7):650-6. 

    • Small Bowel Lymphoma: Facts
      • third most common small bowel malignancy
      • the stomach is the most commonly affected portion of the gastrointestinal tract followed by the small bowel
      • distal ileum has the greatest amount of lymphoid tissue, so it the most commonly affected segment of small bowel
      • Most cases involving the small bowel are non-Hodgkin B-cell lymphoma
      • T-cell lymphoma has a high association with celiac disease and occurs most commonly in the jejunum
    • Small Bowel Lymphoma: Facts
      • risk factors for development of small bowel lymphoma include;
      • acquired immunodeficiency syndrome
      • inflammatory bowel disease
      • immunosuppression after solid organ transplantantion
      • systemic lupus erythematosus
      • Chemotherapy
      • Epstein-Barr virus has a known association with Burkitt lymphoma which commonly occurs in the ileocecal re- gion in pediatric patients
    • Small Bowel Lymphoma: Facts
      In Western countries, B-cell lymphoma of mucosa- associated lymphoid tissue (MALT lymphoma) is the most common subtype of primary small bowel lym- phoma. T-cell lymphomas are much less common and primarily occur in the setting of celiac disease
Vascular

    • Renal Artery Stenosis
      • Majority of renal artery stenosis (90%) is due to atherosclerosis.
      • Risk factors
         - age
         - diabetes
         - aortoiliac occlusive disease
         - hypertension
         - coronary artery disease
    • Renal Artery Stenosis
      • Describe locations
         - atherosclerotic lesions usually arise in the proximal 2 cm or proximal 1/3 of the artery
      • Grade stenosis
      • Characterization of plaque
         - atherosclerotic lesions often calcified
      • Delineation of any secondary findings
    • Renal Artery Stenosis
      • Role of revascularization vs medical therapy for atherosclerotic renal artery stenosis remains controversial
      • Restenosis rate is lower in renal arteries than coronary arteries
      • Emboli into renal vascular bed and elsewhere remains a major concern
    • RAS: Benefits of Stenting
      • improves hypertension
      • stabilizes renal failure
      • reduces recurrent cardiac events such as flash pulmonary edema
    • Fibromuscular Dysplasia: Facts
      • FMD causes less than 10% of renal artery stenosis
      • young or middle aged women
      • associations:
         - smoking
         - hormones
         - vasa vasorum disorders
      • In symptomatic patients, lesions are bilateral in 71%
    • Fibromuscular Dysplasia
      • medial fibroplasia
      • perimedial fibroplasia
      • medial hyperplasia
      • medial dissection
      • intimal fibroplasia
      • adventitial fibroplasia
    • Fibromuscular Dysplasia
      • medial fibroplasia- mid to distal RA
      • perimedial fibroplasia
      • medial hyperplasia
      • medial dissection
      • intimal fibroplasia
      • adventitial fibroplasia
    • Fibromuscular Dysplasia
      • “string-of-beads”
         - beading is larger than normal artery diameter
      • focal, concentric stenos(es)
      • smooth, long stenosis
      • aneurysm(s)
      • dissection
         - intimal and periarterial FMD
      • thrombosis
         - intimal and periarterial FMD
    • Renal Artery Aneurysm
      • hypertension
      • systemic atherosclerosis
      • extrarenal aneurysms
      • FMD
      • arteritis
      • dissection
      • smoking
      • Marfan syndrome
      • Ehlers-Danlos syndrome
      • Neurofibromatosis
      • aortic coarctation
      • infectious etiologies
    • Renal Artery Aneurysms
      • Usually incidental
      • May be symptomatic: pain, hematuria
      • 60% at main artery bifurcation or mainstem artery
      • Bilateral in 19%
      • Multiple in 25-33%
      • ~1/3 of patients have ipsilateral renal artery stenosis
    • Renal Artery Aneurysms : Complications
      • hypertension
      • rupture
      • RA thrombosis
      • infarction by distal embolization
      • AV fistula
    • Renal Artery Aneurysms : Complications
      • Some recommend repair in the setting of pain, or complications, such as dissection or embolization.
      • Endovascular repair has become an alternative treatment option
      • CT can be used to confirm patency following stent-graft occlusion
    • Renal Artery Aneurysms : Repair
      • All aneurysms > 2 cm
      • Most renal artery aneurysms 1.5 to 2 cm
      • RAA> 1 cm in conjunction with risk factors
         - hypertension
         - ipsi or contralateral renal artery stenosis
         - women of childbearing age
    • Renal Artery Aneurysms : Complications
      • Risk of rupture increases during pregnancy and correlates with aneurysm size.
      • Surgical treatment
         - decreased blood pressure in 47-60% of those with preoperative hypertension
         - renal function may be improved
    • Renal Artery Dissection
      • Extension from an abdominal aortic dissection
      • Trauma (blunt or iatrogenic)
      • FMD
      • Anti-phospholipid antibody association
      • Ehlers Danlos
      • Idiopathic
    • Renal Artery Thrombosis
      • Thromboembolic disease- cardiac most common
      • Renal Artery insult
         - Spontaneous/traumatic dissection
         - Fibromuscular dysplasia (FMD)
      • Hypercoaguability
         - Antiphospholipid Syndrome
         - Nephrotic Syndrome
    • Renal Artery Thrombosis: CT Findings
      • Axial image from arterial phase CT
      • Elongated filling defect in right renal artery
      • Sharply demarcated cortical hypoenhancement in right kidney secondary to infarct
      • Infarcts are subtle on early CT
    • Renal AVM
      • Rare, congenital malformation
      • May be large (aneurysmal) and solitary or numerous and small (cirsoid type).
         - Cirsoid type more common. 
      • Usually located in renal sinus
      • Usually solitary and right sided

    • Renal AVM: Presentation
      • gross hematuria
      • hypertension
      • flank pain
      • high cardiac output failure
    • Mesenteric Artery Dissection
      • Isolated celiac or SMA dissection
      • Exclusive of aortic dissection
      • 10% of patients celiac and SMA involved
      • May present acutely w/ abdominal pain
      • Often incidentally identified on CT
         - typically stable without complication
    • Mesenteric Artery Dissection
      • atherosclerosis
      • vasculitis
      • connective tissue disorder
      • Type IV Ehlers-Danlos
      • Trauma
      • fibromuscular dysplasia
      • cystic medial necrosis
      • Hypertension
      • Systemic arterial mediolysis
    • Segmental Arterial Mediolysis
      • Rare noninflammatory vasculopathy
      • Medial layer disrupted
      • Dissection, hemorrhage, ischemia
      • Visceral and mesenteric arteries most common
      • Abdominal pain, GI bleeding
    • Segmental Arterial Mediolysis: CT
      • String of beads
      • Stenoses
      • Aneurysms
      • Dissection
      • Thrombosis
    • SAM: Differential Dx
      • FMD
      • PAN
      • ANCA assoc vaculitis
      • Giant cell arteritis
      • Takayasus
      • Bechets
      • Type IV EDS
    • Superior Mesenteric Artery Syndrome
      • Obstruction of the third portion of the duodenum between the SMA and aorta
      • Cast syndrome, Wilke syndrome
      • Arteriomesenteric duodenal compression syndrome
    • SMAS: CT Criteria
      • Aortomesenteric angle
         - Normally 28 to 65 degrees
         - Reduced to < 22 degrees in SMAS
      • Aortomesenteric distance
         - Normally 10-34 mm
         - Less than 8 mm in SMAS
      • Dilated duodenum and stomach proximal
      • Obstructed left renal vein (“nutcracker”)
    • Median Arcuate Ligament Syndrome
      • Median arcuate ligament runs obliquely between the diaphragmatic crura
      • Low lying ligament can compress celiac artery
      • Various degrees of narrowing and obstruction
      • Median Arcuate Ligament “Syndrome” if patient symptomatic
    • Visceral Arterial Aneurysms
      • splenic artery in 60%–80% of cases
      • hepatic artery in 20%
      • SMA in 5.5%
      • celiac artery in 4%
      • gastric and gastroepiploic artery in 4%,
      • GDA, pancreatic branches in 6%
      • jejunal and ileocolic arteries in 3%
      • IMA in less than 1%
    • Splenic Artery Aneurysms
      • Small and asymptomatic- serial imaging
      • Surgical intervention at 2 cm
      • More aggressive management may be warranted in high risk clinical settings
         - women of childbearing age
         - cirrhotics
    • Celiac Artery Aneurysms
      • Post-stenotic dilatation w/proximal stenosis
      • Atherosclerosis
      • Focal dissection
      • Medial degeneration
      • Genetic syndrome: Ehlers Danlos
    • Celiac Artery Aneurysms
      • Rupture or impending rupture are made apparent by signs and symptoms
         - pain
         - gastrointestinal bleeding
      • Size threshold for surgical repair of celiac artery aneurysms 2 cm in surgical candidates
    • Visceral Arterial Aneurysms
      • Treatment options include surgical vs endovascular approaches based on location
      • For many cases, ligation or coil embolization is the treatment of choice
      • Stents are used primarily in cases of aneurysms of major branches, where preservation of arterial flow is required
    • Pseudoaneurysms
      • Nearly always present with symptoms
      • Only 2.5% of cases presented incidentally
      • Untreated mortality rate approaches 90%
      • Small and large aneurysms can rupture
      • Emergent coil embolization
    • SMA Thrombosis: Causes
      • Embolic
      • Progression of atherosclerosis
      • Trauma
      • Infection
      • Spontaneous
    • SMA Occlusion
      Embolism (57%) > thrombosis
      • half of patients with SMA embolus have cardiac thrombus
      • 40% have atrial fibrillation
      • occlusion more likely to be distally located in the SMA
      • synchronous emboli in other locations in 68%
      Thrombotic occlusion
      • more extensive intestinal infarction
    • Mesenteric Artery Stenosis
      • Atherosclerosis in older patients
      • Median arcuate ligament syndrome
         - younger patients
      • Other causes
         - tumor encasement (pancreatic cancer)
         - pancreatitis
         - vasculitis
    • Mesenteric Ischemia
      • Chronic mesenteric ischemia is caused by occlusive disease of mesenteric vessels
      • Most often due to atheroma
      • Women > men
      • Patients >60 years
      • Severe stenosis (often multivessel) manifests with abdominal pain or other nonspecific symptoms
    • Chronic Mesenteric Ischemia
      • Takayasu disease
      • fibromuscular dysplasia
      • thromboangiitis obliterans
      • periarteritis nodosum
      • radiation therapy
      • median arcuate ligament syndrome
© 1999-2017 Elliot K. Fishman, MD, FACR. All rights reserved.