Comparison of CT angiography with MR angiography in the preoperative assessment of living kidney donors.

BACKGROUND: The aim of the study was to prospectively compare the diagnostic performance of CT angiography (CTA) with MR angiography (MRA) in the preoperative assessment of living renal donors. METHODS: Forty-eight potential living renal donors (mean 51 years, 29-67 years) underwent multislice CTA and gadolinium-enhanced MRA. Six potential donors were excluded. Forty-two donors underwent minimal invasive retroperitoneoscopic nephrectomy (left 36, right 6) and their datasets available for analysis independently performed by two blinded radiologists. The surgical status served as gold standard. RESULTS: In 42 donors (84 kidneys), CTA identified 63 kidneys with 1 artery (MRI 61), 19 with 2 arteries (MRI 20), one with three arteries (MRI 2), and one with four arteries (MRI 1). Considering only the side with the surgical status available for verification, both CT and MRI correctly characterized 35 of 36 donors with a single renal artery and five of six with one supernumerary artery. Two false positives were two arteries suggested as supernumerary both in CT and MRI not confirmed during surgery. CTA and MRA both correctly identified three accessory renal veins in two donors. CONCLUSION: CTA and MRA had the same accuracy for characterization of renal vasculature in the preoperative assessment of living renal donors.

MR angiography of the hand with subsystolic cuff-compression optimization of injection parameters.

OBJECTIVE: The purpose of our study was to assess the impact of various injection rates on contrast-enhanced high-resolution 3D MR angiography of the hand. MATERIALS AND METHODS: Ten healthy individuals (mean age, 24.4 years; range, 20-27 years) underwent 3D contrast-enhanced MR angiography of both hands. Starting 3 minutes before data acquisition, subsystolic upper arm cuff compression was applied unilaterally. A 1.5-T whole-body scanner with 3D gradient-echo sequence was used. Seven data sets (20 seconds) were obtained consecutively. I.v. contrast material of 0.1 mg/kg of body weight of gadobutrol was injected at rates of 0.5, 1.0, and 1.5 mL/s. For both hands, quantitative data evaluation was performed with contrast-to-noise ratio (CNR) in the radial, ulnar, palmar, and digital arteries and veins. Qualitative assessment of the arterial visualization score and venous contamination score was rated by two experienced radiologists using a 4-point scale. RESULTS: The lowest venous contamination score (CNR and reviewers' assessment) was observed with an injection rate of 0.5 mL/s (p < 0.05). For the arterial signal, the reviewers' assessment was that an injection rate of 0.5 mL/s was best (p = 0.08). Compression yielded a significantly lower venous contamination score for the compressed side than for the noncompressed side for flow rates of 0.5 mL/s and 1.0 mL/s (p < 0.05). CONCLUSION: Image quality of hand MR angiography was better with cuff compression. A flow rate of 0.5 mL/s yielded a good CNR and a significantly lower venous contamination score than the other flow rates.

Characterization of lesions missed on interpretation of CT colonography using a 2D search method.

OBJECTIVE: We examined potential factors that may cause false-negative results on CT colonography examinations. MATERIALS AND METHODS: In this prospective and retrospective study, 500 asymptomatic patients at high risk for colorectal cancer underwent CT colonography and colonoscopy. Each CT data set was interpreted by two independent observers, who were unaware of endoscopic findings, using a method of searching through enlarged axial images to detect intraluminal lesions. Another observer identified and characterized lesions missed at prospective interpretation. Polyps were assessed for size, method of visualization, intrinsic and extrinsic features, and examination quality. RESULTS: We found 116 polyps at least 5 mm in diameter, 54 (47%) of which were missed by at least one of the prospective observers. Polyps seen in only one position were missed more often than polyps seen in both supine and prone positions (84% vs 50%, p < 0.01). Polyps located in suboptimally prepared colonic segments or along a thickened colonic wall were more frequently missed (p = 0.02 and p = 0.05, respectively). Endoscopic morphology and irregular surface contour were associated with missed lesions of all sizes (p = 0.03 and p = 0.04, respectively). Rounded intraluminal lesions were detected more often than other morphologies on CT (p = 0.04). CONCLUSION: Factors that influence the likelihood that a polyp may be missed at interpretation of CT colonography include being seen only in one position, having flat endoscopic or CT morphology, having surface irregularity, and being located in a poorly prepared segment or along a thickened colonic wall. Understanding these features should lead to improved polyp detection on CT colonography.

Colorectal cancer screening with CT colonography, colonoscopy, and double-contrast barium enema examination: prospective assessment of patient perceptions and preferences.

PURPOSE: To prospectively assess and compare perceptions of and preferences for computed tomographic (CT) colonography, colonoscopy, and double-contrast barium enema examination (DCBE) by asymptomatic patients undergoing colorectal cancer screening. MATERIALS AND METHODS: A total of 696 asymptomatic patients at higher-than-average risk undergoing colorectal cancer screening were consecutively recruited to undergo both CT colonography and colonoscopy (group 1), and a like group of 617 patients was separately recruited to undergo both CT colonography and DCBE (group 2). Standard bowel preparations were different between the groups undergoing colonoscopy and DCBE. Each patient completed a questionnaire that assessed preparation inconvenience and discomfort, examination discomfort, willingness to repeat examinations, and examination preference. Survey results were compared for significance by using the Wilcoxon rank sum or chi2 test. RESULTS: The majority of patients considered the preparation to be uncomfortable (group 1, 460 of 515 [89%]; group 2, 482 of 538 [90%]) and inconvenient (group 1, 393 of 502 [78%]; group 2, 427 of 527 [81%]). Reported discomfort was similar at CT colonography and colonoscopy (P =.63) but was less at CT colonography than at DCBE (P <.001). Patients experienced significantly less discomfort than expected at both CT colonography and colonoscopy but not at DCBE. Patients' willingness to undergo frequent rescreening was significantly greater for CT colonography than for either colonoscopy or DCBE. The acceptable time interval between screenings was significantly shorter for all examinations if the bowel preparation could be avoided. Overall, patients preferred CT colonography to colonoscopy (group 1, 72.3% vs 5.1%; P <.001) or to DCBE (group 2, 97.0% vs 0.4%; P <.001). CONCLUSION: Patients undergoing colorectal cancer screening prefer CT colonography to both colonoscopy and DCBE. The majority of patients experience discomfort and inconvenience with cathartic bowel preparation.

Extracolonic findings at CT colonography: evaluation of prevalence and cost in a screening population.

BACKGROUND & AIMS: To assess the prevalence and spectrum of extracolonic findings in a screening population undergoing computed tomography colonography (CTC), and to evaluate the short-term direct medical costs incurred from subsequent radiologic follow-up evaluation. METHODS: Six hundred and eighty-one asymptomatic patients undergoing colonoscopy screening consented to a CTC examination. Extracolonic CT findings were classified into high, medium, and low importance. Clinical and radiologic follow-up, missed lesions, and outcomes were assessed by chart review (time interval, 410-1513 days; median, 913 days). Short-term direct medical costs of radiologic follow-up were determined based on Medicare 2002 reimbursement rates. RESULTS: Extracolonic findings were found commonly. These were categorized as high clinical importance in 71 (10%) individuals, as medium importance in 183 individuals (27%), and as low importance in 341 individuals (50%). Subsequent medical or surgical interventions resulted from these findings in 9 of the 681 patients (1.3%). Costs of subsequent radiologic follow-up studies were calculated as $23,380.59 (average added costs per CTC examination $34.33). CONCLUSIONS: CTC commonly detects extracolonic findings that can be considered clinically important when applied to an asymptomatic screening population. Although such incidental findings add benefit to the screening intervention, moderate incremental costs are incurred based on additional radiologic procedures generated during short-term follow-up.

Diseases of the cecum: a CT pictorial review.

Cecal pathology is commonly encountered and may represent a diagnostic challenge in patients with either acute or chronic clinical presentations. Although appendicitis accounts for the majority of surgical conditions presenting with right lower quadrant pain, readers should be aware of the broad spectrum of cecal pathologies and characteristic CT findings, which can be useful in establishing the correct diagnosis.

Diseases of the cecum: a CT pictorial review.

Cecal pathology is commonly encountered and may represent a diagnostic challenge in patients with either acute or chronic clinical presentations. Although appendicitis accounts for the majority of surgical conditions presenting with right lower quadrant pain, readers should be aware of the broad spectrum of cecal pathologies and characteristic CT findings, which can be useful in establishing the correct diagnosis.