MRI assessment of biliary ductal obstruction: is there added value of T1-weighted gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced MR cholangiography?

OBJECTIVE: The goal of the present study was to determine the added value of gadolium-ethoxybenzyl-diethylenetriamine pentaacetic acid (gadoxetate disodium)-enhanced magnetic resonance cholangiography (MRC) to standard liver MRI including T2-weighted MRCP in assessment of biliary ductal obstruction. MATERIALS AND METHODS: Thirty-eight patients (mean age, 48.1 ± 16.7 years) (40 total examinations) who underwent liver MRI (including T2-weighted MRCP and gadoxetate disodium-enhanced MRC) for suspicion of biliary disease were included in this institutional review board-approved, HIPAA-compliant retrospective study. Three blinded radiologists first evaluated MR images without gadoxetate disodium-enhanced MRC for presence and significance of biliary obstruction, underlying cause for obstruction, and confidence in final diagnosis. After inclusion of gadoxetate disodium-enhanced MRC, readers again determined presence and significance of biliary obstruction and confidence in final diagnosis. Reference standard was established using MRI along with ERCP, percutaneous transhepatic cholangiography, intraoperative cholangiography, or a combination thereof. RESULTS: Overall sensitivity across all readers in diagnosing significance of obstruction was 60% without gadoxetate disodium-enhanced MRC and 91% with gadoxetate disodium- enhanced MRC (p < 0.001). Across all readers, assessment of significance of obstruction was changed when adding gadoxetate disodium-enhanced MRC in 40 of 120 cases (33%); significance of obstruction was correctly changed in 35 of 40 cases (87.5%). Biliary obstruction was graded of unknown significance in 27 of 120 cases (22.5%) across all readers when gadoxetate disodium-enhanced MRC was not reviewed. Significance of biliary obstruction was classified correctly after adding gadoxetate disodium-enhanced MRC in 25 of these 27 cases (93%). Confidence in final diagnosis was significantly higher with addition of gadoxetate di-sodium-enhanced MRC for two of three readers (p < 0.003). CONCLUSION: Addition of gadoxetate disodium-enhanced MRC to liver MRI significantly improves sensitivity in assessing significance of biliary obstruction and can improve reader confidence in establishing a final diagnosis. This added information could have a substantial impact in the determination of the most appropriate therapeutic options.

Renal cortical thickness measured at ultrasound: is it better than renal length as an indicator of renal function in chronic kidney disease?

OBJECTIVE: The purpose of our study was to determine whether there is a relationship between renal cortical thickness or length measured on ultrasound and the degree of renal impairment in chronic kidney disease (CKD). MATERIALS AND METHODS: From October to December 2007, 25 patients (13 men and 12 women, mean age 73 years) were identified who had CKD but were not on dialysis. The patients were from a single institution and had undergone renal ultrasound and at least three serum creatinines within 90 days. The lowest creatinine was used for estimated glomerular filtration rate (eGFR) calculation using both the Cockcroft-Gault (CG) and the Modification of Diet in Renal Disease Study (MDRD) equations. Ultrasounds were consensus reviewed by three radiologists (2 attendings and a resident) blinded to specific renal function. Cortical thickness was measured in the sagittal plane over a medullary pyramid, perpendicular to the capsule. Length was measured pole-to-pole. Linear regression was used for statistical analysis. RESULTS: Mean cortical thickness was 5.9 mm (range, 3.2-11.0 mm). Mean length was 10 cm (7.2-12.4 cm). Mean minimum serum creatinine was 2.1 mg/dL (1.1-6.1 mg/dL). Mean eGFR using CG was 34.8 mL/min (10.6-99.4 mL/min) and 36 mL/min (8-66 mL/min) using MDRD. There was a statistically significant relationship between eGFR and cortical thickness using both CG (p < 0.0001) and MDRD (p = 0.005). There was a statistically significant relationship between CG and length (p = 0.003) but not between MDRD and length (p = 0.08). CONCLUSION: Cortical thickness measured on ultrasound appears to be more closely related to eGFR than renal length. Reporting cortical thickness in patients with CKD who are not on dialysis should be considered.

Prevalence and nature of excluded findings at reduced scan length CT angiography for pulmonary embolism.

BACKGROUND: Scan length reduction effectively decreases radiation dose at CT pulmonary angiography (CTPA) for pulmonary embolism (PE) but may exclude important incidental scan findings. OBJECTIVE: We aimed to determine the prevalence and nature of excluded findings with the use of reduced scan length CTPA. METHODS: We reviewed 335 consecutive emergency department CTPA studies performed on 16- or 64-detector row scanners with the use of a standard scan range. A scan length of 14.2 cm that was centered 4.1 cm below the carina has been shown to be adequate for PE diagnosis. Boundary slices for this scan range were determined. All pertinent and incidental findings within and outside the reduced scan range were noted. To determine the significance of newly detected excluded findings, we reviewed medical records and all relevant imaging studies before and 9-11 months after the reference CTPA. RESULTS: We found 374 pertinent findings in 192 patients, including 28 (8%) cases of PE. All except 3 (0.8%) were adequately seen with the reduced scan range, among which only one finding altered clinical management. There were a total of 230 incidental findings in 165 patients, 60 (26%) of which were excluded; 23 (10%) of the 60 were newly detected, including 10 thyroid nodules, 6 liver lesions, and an 8-mm pulmonary nodule. The reduced scan length decreased z-axis coverage by 49% ± 6%. CONCLUSION: Substantial scan length reduction at CTPA may not compromise the diagnostic yield for pertinent alternative diagnoses.