Abdominal and pelvic aneurysms and pseudoaneurysms: imaging review with clinical, radiologic, and treatment correlation.

Abnormally enlarged visceral arteries in the abdomen and pelvis must be recognized radiologically because early treatment can improve the quality of life and prevent life-threatening complications. These lesions, typically classified as aneurysms and pseudoaneurysms, are being detected more frequently with increased utilization of imaging and have various causes (eg, atherosclerosis, trauma, infection) and complications that may be identified radiologically. Ultrasonography, computed tomography, and magnetic resonance imaging often enable detection of visceral vascular lesions, but angiography is important for further diagnosis and treatment. Endovascular treatment is often the first-line therapy. Endovascular intervention or open surgical repair is necessary for all visceral pseudoaneurysms and is likely indicated for visceral aneurysms 2 cm or more in diameter. Endovascular exclusion of flow can be achieved with coils, stents, and injectable liquids. Techniques include embolization ("sandwich" or "sac-packing" technique), exclusion of flow with luminal stents, and stent-assisted coil embolization. Management often depends on the location and technical feasibility of endovascular repair. Embolization is usually preferred for aneurysms or pseudoaneurysms within solid organs, and the sandwich technique is often used when collateral flow is present. Covered stent placement may be preferred to preserve the parent artery when main visceral vessels are being treated. It is usually tailored to lesion location, and a cure can often be effected while preserving end-organ arterial flow. Posttreatment follow-up is usually based on treatment location, modality accuracy, and potential consequences of treatment failure. Follow-up imaging may help identify vessel recanalization, unintended thrombosis of an artery or end organ, or sequelae of nontarget embolization. Retreatment is usually warranted if the clinical risks for which embolization was performed are still present.

Computerized tomography magnified bone windows are superior to standard soft tissue windows for accurate measurement of stone size: an in vitro and clinical study.

PURPOSE: We determined the most accurate method of measuring urinary stones on computerized tomography. MATERIALS AND METHODS: For the in vitro portion of the study 24 calculi, including 12 calcium oxalate monohydrate and 12 uric acid stones, that had been previously collected at our clinic were measured manually with hand calipers as the gold standard measurement. The calculi were then embedded into human kidney-sized potatoes and scanned using 64-slice multidetector computerized tomography. Computerized tomography measurements were performed at 4 window settings, including standard soft tissue windows (window width-320 and window length-50), standard bone windows (window width-1120 and window length-300), 5.13x magnified soft tissue windows and 5.13x magnified bone windows. Maximum stone dimensions were recorded. For the in vivo portion of the study 41 patients with distal ureteral stones who underwent noncontrast computerized tomography and subsequently spontaneously passed the stones were analyzed. All analyzed stones were 100% calcium oxalate monohydrate or mixed, calcium based stones. Stones were prospectively collected at the clinic and the largest diameter was measured with digital calipers as the gold standard. This was compared to computerized tomography measurements using 4.0x magnified soft tissue windows and 4.0x magnified bone windows. Statistical comparisons were performed using Pearson's correlation and paired t test. RESULTS: In the in vitro portion of the study the most accurate measurements were obtained using 5.13x magnified bone windows with a mean 0.13 mm difference from caliper measurement (p = 0.6). Measurements performed in the soft tissue window with and without magnification, and in the bone window without magnification were significantly different from hand caliper measurements (mean difference 1.2, 1.9 and 1.4 mm, p = 0.003, <0.001 and 0.0002, respectively). When comparing measurement errors between stones of different composition in vitro, the error for calcium oxalate calculi was significantly different from the gold standard for all methods except bone window settings with magnification. For uric acid calculi the measurement error was observed only in standard soft tissue window settings. In vivo 4.0x magnified bone windows was superior to 4.0x magnified soft tissue windows in measurement accuracy. Magnified bone window measurements were not statistically different from digital caliper measurements (mean underestimation vs digital caliper 0.3 mm, p = 0.4), while magnified soft tissue windows were statistically distinct (mean underestimation 1.4 mm, p = 0.001). CONCLUSIONS: In this study magnified bone windows were the most accurate method of stone measurements in vitro and in vivo. Therefore, we recommend the routine use of magnified bone windows for computerized tomography measurement of stones. In vitro the measurement error in calcium oxalate stones was greater than that in uric acid stones, suggesting that stone composition may be responsible for measurement inaccuracies.