Multidetector CT and CT angiography in mesenteric ischemia

Purpose

To evaluate the role of 64-multidetector CT in assessment of mesenteric vascular ischemia in clinically suspected patients.

Patients and methods

This study included 38 patients during period from October 2009 to October 2011. The patients age ranged from 38 to 72 year old (mean age was 57 ± 11.2 years). All cases met the criteria of acute non traumatic (28 patients) or chronic abdominal pain (10 patients) and suspected mesenteric vascular ischemia. All 38 cases were evaluated in surgery department, then underwent CT of the abdomen and pelvis & CTA by using 64 multislice GE light speed VCT. MDCT& CT angiographic findings were correlated with surgical findings in acute mesenteric ischemia (AMI) cases & conventional angiography in chronic mesenteric ischemia (CMI) cases.

Results

MDCT findings alone were nonspecific for detection of MI. The sensitivity, specificity& accuracy of CTA in diagnosis of AMI after surgical confirmation were 96%, 66.6% & 92.8% respectively, while in CMI the sensitivity, specificity & accuracy were 88.8%, 100%, 90% respectively, after confirmation by conventional angiography.

Conclusion

CTA scan appears to be an excellent tool to find out and localize cases of AMI rather than in CMI cases.     

Evaluating mesenteric ischemia with multidetector-row CT angiography

Multidetector-row computed tomographic (MDCT) angiography is an established non-invasive imaging modality to evaluate the mesenteric vasculature. It has an important role in diagnostic algorithms for assessment of suspected acute and chronic mesenteric ischemia. Clinical success for synchronizing a MDCT volumetric acquisition with a bolus of contrast medium and also for depicting vascular pathology with high accuracy relies on implementing several key principles. This can be more challenging with advanced generation MDCT scanners. This article reviews the technical principles fundamental to evaluating the mesenteric vasculature with MDCT angiography. An overview of clinical application is also presented.     

Acute and chronic mesenteric ischemia: Multidetector CT and CT angiographic findings

Aim of the work

To assess the role of multidetector CT (MDCT) and CT angiography (CTA) in the diagnosis of acute and chronic mesenteric ischemia.

Patients and methods

This prospective study was performed on 57 consecutive patients clinically suspected of having mesenteric ischemia, they were examined with 16-row multidetector CT, MDCT and CTA were evaluated for evidence of bowel wall changes and abnormal mesenteric vascular changes.

Results

Twenty one patients of studied 57 patients had an abnormal CTA finding diagnostic of mesenteric ischemia and they constituted the material of this study, the most prevalent MDCT findings were bowel wall thickening, bowel distension and non-enhanced bowel wall. MDCT and CTA gave an accurate diagnosis of the cause of mesenteric ischemia as proved by the final diagnosis based on surgical exploration, conventional angiography, laboratory investigations and clinical follow up with 100% sensitivity and specificity.

Conclusion

MDCT and CTA are fast, safe, accurate and non-invasive imaging modalities of choice in patients with suspected mesenteric ischemia which are able to evaluate not only mesenteric vascular structures but also evaluate bowel wall changes and adjacent mesentery, thus detecting the primary cause of mesenteric ischemia that can lead to earlier diagnosis and intervention.     

Multidetector CT angiography in Takayasu arteritis

Objective

To analyse the spectrum of Takayasu's arteritis (TA) on multidetector CT angiography (MDCTA).

Materials and methods

A retrospective analysis of the MDCTA findings was performed on 15 patients clinically diagnosed as Takayasu's arteritis. The spectrum and incidence of imaging findings on CTA were compared to studies in literature on catheter angiography in Takayasu's arteritis. Laboratory parameters were available in nine patients. The disease was considered active if erythrocyte sedimentation rate (ESR) levels were elevated and ‘C’ reactive protein (CRP) was positive. An attempt was made to correlate disease activity with the imaging findings.

Results

Ascending aorta, arch of aorta and descending thoracic aorta were involved in 14 out of 15 (93%) patients. The wall thickness varied between 1 and 10 mm with maximal involvement in arch and descending thoracic aorta. Major neck vessels were involved in 11 (73%) patients with most pronounced changes seen in the brachiocephalic trunk, left common carotid artery (CCA) and left subclavian artery (SCA). Abdominal aorta and its branches were involved in all the 11 (100%) patients in whom abdominal CTA was performed. Celiac axis and SMA were involved in 10 (91%) and seven (64%) patients, respectively while renal artery stenosis was present in five (45%) patients. In six patients, ESR was elevated and CRP was positive indicating active disease. All patients in whom the laboratory parameters were available showed mural thickening in the aorta and at least one of the neck vessels except for one patient with inactive disease who had aortic mural thickening only.

Conclusion

MDCTA provides information about both the vessel wall and lumen in patients with Takayasu's disease.     

ECG门控双源CT胸痛检查模式的辐射剂量估测

目的是评估应用ECG门控双源CT检查胸痛的模式的辐射剂量。采用装有热释光剂量仪的Alderson Rando模型测定剂量。在不同模拟心率（HR）下应用双源CT系统以评估胸痛的标准模式（120kV，320mAs／r）曝光，并测量标准胸部CT检查（120kV，160mAs）的剂量。胸痛模式的有效剂量男、女分别为19．3、21．9mSv（HR60），17．9、20．4mSv（HR80）和14．7、16．7mSv（HR100）。     

Multidetector CT angiography in the diagnosis of mesenteric ischemia

Multidetector CT is an ideal tool for the diagnosis of acute and chronic mesenteric ischemia. Advanced CT scanners and expertise in three-dimensional imaging are becoming increasingly widespread, opening the door to new opportunities and challenges in the evaluation of patients suspected of having mesenteric ischemia. This article reviews contrast administration and image acquisition protocols, the anatomy of the mesenteric vasculature, the etiology of acute and chronic mesenteric ischemia, and CT findings diagnostic for these conditions.     

Limitations of angiography for mesenteric ischemia caused by midgut carcinoid tumors

Mesenteric ischemia associated with carcinoid tumors often presents with nonspecific abdominal pain and is usually due to mesenteric branch artery occlusion caused by elastic vascular sclerosis. Mesenteric ischemia was defined by the operative findings of cyanosis or infarction. Eleven patients with intraabdominal metastatic carcinoid tumor were evaluated by angiography. Angiographic narrowing and occlusion of multiple peripheral jejunal and ileal intramesenteric branch arteries was present in 3 patients with mesenteric ischemia, but also occurred in 5 of 8 patients without mesenteric ischemia. Other angiographic abnormalities included staining of the primary tumor (5) or metastases (6), tenting of small mesenteric vessels (5), and occlusion of draining mesenteric veins (2). We conclude that in patients with midgut carcinoid tumors, angiographic narrowing and occlusion of peripheral mesenteric arteries most likely represents elastic vascular sclerosis, is indicative of mesenteric invasions of tumor, but correlates poorly with the presence of ischemia in the subtended bowel. Alternatively, a normal selective arteriogram should exclude mesenteric ischemia as the cause of abnormal pain.     

Multidetector CT of the kidney

The technological development of multidetector CT offers new possibilities for better imaging of organic structures that can be used in diagnosis of the kidney. The thinner slices allow a better spatial resolution, and slice fusion allows improved contrast resolution. The isotropic voxel has been realized in the latest 64-channel scanners. The image quality of arbitrarily reconstructed planes has arrived at the image quality of the scan plane. Faster scanning allows studies in different contrast phases, which is helpful for better discrimination of benign or malignant lesions especially in the highly vascularized kidney. Different phases of contrast uptake can be differentiated (arterial, cortico-medullary, nephrographic, and excretory phase). Multidetector CT brings along the risk of increased dose due to thinner slice collimation and overranging phenomena. Indications for CT investigation of the kidney include urolithiasis, tumor diagnosis and staging, renal trauma, and vascular disease. Even in children, special indications for CT of the kidney remain in polytrauma and tumor staging. Multidetector CT of the kidney has become a very valuable tool in urology, but a careful protocol strategy is mandatory.     

Multi-detector CT angiography of the intra-cranial circulation: normal anatomy and pathology with angiographic correlation

Multidetector computed tomography angiography (MD-CTA) of the intra-cranial circulation shows great potential in the evaluation of intra-cranial vascular disease. Interpreting these studies requires a detailed knowledge of the technique, its advantages and disadvantages, as well as a strong understanding of normal intra-cranial vascular anatomy. The purpose of this review is to describe the technique for MD-CTA, demonstrate normal anatomy, anatomic variants and vascular pathology with an emphasis on aneurysms.     

急性肠系膜缺血的DSA诊断和经皮血管内治疗的临床价值探讨

目的:探讨急性肠系膜缺血的DSA诊断价值和经皮血管内治疗的临床应用价值。方法:12例临床疑诊患者,均经皮行右侧股动脉穿刺、插管,依次进行升主动脉、腹主动脉、腹腔干和肠系膜上、下动脉造影。其中8被诊断为急性肠系膜缺血,急性肠系膜上动脉栓塞4例;急性肠系膜上动脉血栓形成3例,非闭塞性肠系膜缺血1例。对4例肠系膜上动脉栓塞患者经导管注入溶栓剂(尿激霉)和血管扩张剂(罂粟碱)治疗,2例治疗后血管开通;另2例因症状缓解不明显行外科手术治疗;3例病程较长者造影后直接转外科进行手术治疗。结果:DSA诊断急性肠系膜上动脉栓塞4例。造影表现为肠系膜上动脉主干远端(中结肠动脉起始部)或分支的突然截断(截断征)或管腔内局限性充盈缺损(不完全栓塞)。急性肠系膜上动脉血栓3例,造影表现为肠系膜上动脉起始部的狭窄。1例造影表现为肠系膜上动脉分支弥漫性痉挛(腊肠征)诊断为非闭塞性肠系膜动脉缺血,手术证实为急性肠系膜静脉血栓形成。手术后1周因再次肠坏死而死亡。1例广泛血栓形成患者于造影后6h死亡。另2例肠系膜上动脉血栓患者手术后2周死亡。结论:DSA是诊断各型急性肠系膜缺血的有效手段,可以明确病变的部位和范围,为手术治疗提供定位信息。对急性肠系膜静脉血栓的诊断有一定的局限性。经导管溶栓术是治疗肠系膜动脉栓塞的有效手段。亦可作为外科手术前的辅助治疗手段,减少死亡率。     

CT in acute mesenteric ischaemia

Enhanced computed tomography (CT) is frequently performed for possible bowel ischaemia. It has the distinct advantage of possible detection of the causes of ischaemia. Radiologists therefore need to be familiar with the spectrum of diagnostic CT signs. We present the CT imaging findings in surgically proven cases of small bowel ischaemia. In addition to signs pertaining to the underlying aetiological pathology, bowel dilatation, bowel wall thickening, mural gas, occlusion of mesenteric vessels, ascites and infarct of other abdominal organs were observed.     

急性非闭塞性肠系膜血管缺血的诊断和介入治疗

目的探讨选择性肠系膜上动脉造影,经肠系膜上动脉持续灌注罂粟碱在诊断和治疗急性非闭塞性肠系膜血管缺血(NOMI)的价值。方法回顾分析从1999年8月到2005年3月经选择性肠系膜上动脉造影确诊,并行介入诊疗的18例NOMI。明确NOMI诊断后即行经导管肠系膜上动脉灌注罂粟碱治疗。结果本组18例NOMI中15例患者治愈;3例有效,介入治疗后腹痛减轻,但仍有局限性的腹膜刺激征,转外科行肠切除治愈;1例10d后死于严重肺部感染导致的呼吸衰竭。结论选择性肠系膜上动脉造影持续经导管肠系膜上动脉灌注罂粟碱是NOMI有效的诊断和治疗方法。     

Multidetector CT Urography in Imaging of the Urinary Tract in Patients with Hematuria

This review article comprehensively discusses multidetector CT urography protocols and their role in imaging of the urinary tract in patients with hematuria.     

Biphasic CT with mesenteric CT angiography in the evaluation of acute mesenteric ischemia: initial experience

PURPOSE: To evaluate the sensitivity and specificity of biphasic computed tomography (CT) with mesenteric CT angiography in the diagnosis of acute mesenteric ischemia (AMI). MATERIALS AND METHODS: Sixty-two patients with clinically suspected AMI underwent prospective imaging with biphasic multi-detector row CT. Mesenteric CT angiography was performed with 1.25-mm collimation starting 25 seconds after 140 mL of intravenous contrast agent was administered at a rate of 4 mL/sec, followed by portal venous phase imaging with 5-mm collimation and a 60-70-second delay. CT angiograms were reconstructed with multiplanar (including transverse), maximum intensity projection, and volume-rendered techniques. All scans were evaluated prospectively by two independent radiologists for CT evidence of ischemia. AMI was confirmed with surgical or pathologic proof in 25 of 26 patients. In one patient, AMI was confirmed with clinical findings and serial CT examinations. In patients with AMI, sensitivity and specificity of each CT sign were calculated retrospectively by using patients who did not have intestinal ischemia as a control group. CT criteria that optimized sensitivity and specificity for the diagnosis of AMI were then developed. RESULTS: AMI was diagnosed in 26 patients. The CT angiogram depicted arterial disease in eight patients and altered care in five. A finding of any one of pneumatosis intestinalis, venous gas, superior mesenteric artery occlusion, celiac and inferior mesenteric artery occlusion with distal SMA disease, or arterial embolism was 100% specific but only 73% sensitive. Alternatively, a finding of bowel wall thickening in addition to focal lack of bowel wall enhancement, solid organ infarction, or venous thrombosis was 50% sensitive and 94% specific. By using either of these criteria for the diagnosis, a sensitivity of 96% and a specificity of 94% can be achieved. CONCLUSION: Biphasic CT with mesenteric CT angiography is effective in the diagnosis of AMI.     

Multidetector and three-dimensional CT evaluation of the patient with maxillofacial injury

Interpretation of images associated with the traumatically injured face is challenging. The complexity of facial anatomy, coupled with the superimposition of numerous bony structures on plain radiographs, poses specific obstacles to accurate interpretation of facial injury. Although plain radiographs can be helpful in cases of isolated injuries, CT is the most useful modality for evaluating facial injury. This article reviews facial anatomy as it pertains to traumatic injury, emphasizes the clinical findings associated with various types of facial injury, and simplifies the diagnosis of facial injury on CT.     

Multidetector helical CT in the evaluation of acute small bowel obstruction: comparison of non-enhanced (no oral, rectal or IV contrast) and IV enhanced CT

Purpose

To compare accuracy of non-enhanced CT (NECT) (no oral or IV contrast) and enhanced CT (ECT) (IV enhanced only) to diagnose small bowel obstruction and evaluate reviewer's experience impact.

Materials and methods

Ninety-nine adult patients underwent 105 NECT and ECT (6 patients had 2 examinations) on a four-detector CT. An abdominal radiologist, an abdominal imaging fellow, a second-year radiology resident retrospectively reviewed NECTs and ECTs separately and independently blinded to outcome. Discrepancy of diameter of proximal and distal small bowel ± a transition was considered indication of mechanical bowel obstruction. Reference standard was surgery in 26 and chart review in 79.

Results

Mechanical obstruction was present in 56% (59/105). The average sensitivity, specificity, negative and positive predictive and accuracy values for NECT were 88.1% (CI: 80-96%), 77% (CI: 65-89%), 83.0% (CI: 72-95%), 83% (CI: 74-92%), and 83% (CI: 76-90%) with no significant difference between three reviewers. The corresponding numbers for ECT were 87.6% (CI: 79-96%), 75% (CI: 63-88%), 82.6.0% (CI: 71-94%), 82.1% (CI: 73-92%), and 82% (CI: 75-90%) (p > 0.5). Area under curve (AUC) of ROC curves of three reviewers did not show significant statistical difference (p > 0.5).

Conclusions

NECT and ECT have comparable accuracy to diagnose mechanical small bowel obstruction and can be interpreted by reviewers with different levels of expertise.     

Post traumatic arterial occlusive mesenteric ischemia: a rare case report

Mesenteric ischemia is an uncommon condition with very high mortality rates characterized by inadequate blood supply, inflammatory injury, and subsequent necrosis of the bowel wall. Acute arterial mesenteric ischemia is usually caused by cardiac emboli, atherosclerotic vascular disease, aortic aneurysm, or dissection. We report a case of a 60-year-old male who presented to the accident and emergency department complaining of abdominal pain following blunt abdominal trauma. An urgent contrast enhanced computed tomography scan demonstrated superior mesenteric artery thrombosis with ischemic small bowel. Surgical intervention was carried out with resection of the necrotic bowel followed by anastomosis. Acute occlusive mesenteric ischemia needs to be considered in cases of blunt trauma presenting with abdominal pain. Proper early diagnosis and management is essential as it carries a high risk of morbidity and mortality.     

64 Multidetector CT angiography in preoperative evaluation of hepatic artery

Purpose

To evaluate the role of 64 multidetector CT angiography in preoperative evaluation of hepatic artery in candidates who underwent hepatic resection.

Materials and methods

Sixty-seven patients underwent triphasic CT scan using 64 multidetector CT scanner. They were 33 with hepatocellular carcinoma, 21 with solitary metastases, seven potential donors for liver transplantation, five with gaint haemangiomas, and one with large primary Non-Hodgkin lymphoma. The images were analyzed for the depiction of hepatic artery. The frequencies of anatomical variants of the hepatic artery were evaluated based on the classification proposed by Michels’ in 1966. The findings was compared and correlated with operative data.

Results

Type I variant was seen in 43 patients (64.2) and variants were seen in other 24 patients (35.8%). We found seven patients with type II variant, 11 patients with type III variant, two patients with type V variant, and two patients with VI variant. There were two patients with type variants did not fit Michels’ classification. In 55 patients, the surgical findings concurred with 64 MDCT angiography findings (100%).

Conclusion

64 MDCT angiography is an effective, high-resolution, noninvasive imaging technique that readily demonstrates the hepatic arterial map with direct impact on treatment decisions including patient selection for hepatic resection.     

Preliminary examination to determine the suitable contrast material injection protocol for CT angiography of the pelvis and lower extremities with a multidetector row helical scanner

Purpose The aim of this study was to determine the best of three protocols for the depiction of arteries in the pelvis and lower extremities by computed tomographic angiography (CTA) with a multidetector row helical scanner. Materials and methods CTA was performed in five asymptomatic volunteers using a four-channel multidetector row helical scanner. Low-osmolar iodinated contrast material was injected at the flow rate of 3 ml/s using three protocols: 100 ml of 300 mg I/ml, 150 ml of 300 mg I/ml, and 100 ml of 350 mg I/ml. The CT number of opacified blood was measured at six levels. Three doctors independently assessed the degree of depiction of arteries on CTA images without knowing the protocol using a 3-point scale. Results CT numbers at the level of the popliteal artery on the protocol of 150 ml of 300 mg I/ml were significantly greater than the others. The mean score for the depiction of trifurcation on the protocol of 150 ml of 300 mg I/ml was significantly greater than those in the others. Conclusion The protocol of 150 ml of 300 mg I/ml was the best for depicting arteries in the pelvis and lower extremities by CTA.     

Non-occlusive mesenteric ischemia: etiology, diagnosis, and interventional therapy

Non-occlusive mesenteric ischemia (NOMI) compromises all forms of mesenteric ischemia with patent mesenteric arteries. It generally affects patients over 50 years of age suffering from myocardial infarction, congestive heart failure, aortic insufficiency, renal or hepatic disease and patients following cardiac surgery. Non-occlusive disease accounts for 20-30% of all cases of acute mesenteric ischemia with a mortality rate of the order of 50%. Acute abdominal pain may be the only early presenting symptom of mesenteric ischemia. Non-invasive imaging modalities, such as CT, MRI, and ultrasound, are able to evaluate the aorta and the origins of splanchnic arteries. Despite the technical evolution of those methods, selective angiography of mesenteric arteries is still the gold standard in diagnosing peripheral splanchnic vessel disease. In early non-occlusive mesenteric ischemia, as opposed to occlusive disease, there is no surgical therapy. It is known that mesenteric vasospasm persists even after correction of the precipitating event. Vasospasm frequently responds to direct intra-arterial vasodilator therapy, which is the only treatment that has been shown to be effective.