Faculty Bibliography

Purpose: To retrospectively evaluate the frequency of recommendations for additional imaging (RAIs) for important extracolonic findings and polyp prevalence among a cohort of seniors (age >/= 65 years) and nonseniors (age < 65 years) undergoing low-dose computed tomographic (CT) colonography. Materials and Methods: Institutional review board approval was obtained for this HIPAA-compliant retrospective study. Four hundred fifty-four patients (204 nonseniors: mean age, 52 years; 250 seniors: mean age, 69 years) underwent CT colonography at an outpatient facility. Cases were prospectively reported by one of four abdominal radiologists with expertise in CT colonography. The dictated reports were reviewed to determine the frequency of polyps (>/=6 mm), the number of extracolonic findings, and the number of RAIs generated. The Fisher exact test was used to compare the percentage of seniors and nonseniors with at least one reported polyp, with at least one extracolonic finding, as well as the frequency of RAIs. Results: The percentage of patients with at least one reported polyp was 14.2% (29 of 204) for the nonsenior group and 13.2% (33 of 250) for seniors, which was not significantly different (P = .772). The percentage of patients with at least one extracolonic finding was 55.4% (113 of 204) for nonseniors and 74.0% (185 of 250) for seniors (P < .0001). The percentage of patients in which an RAI was suggested was 4.4% (nine of 204) for nonseniors and 6.0% (15 of 250) for seniors, which was not significantly different (P = .450). Conclusion: Extracolonic findings were more frequent in seniors than in nonseniors; however, there was no significant difference in the frequency of RAIs between the two groups. (c) RSNA, 2011 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11102144/-/DC1

High-resolution magnetic resonance imaging (MRI) of trabecular bone combined with quantitative image analysis represents a powerful technique to gain insight into trabecular bone micro-architectural derangements in osteoporosis and osteoarthritis. The increased signal-to-noise ratio of ultra high-field MR (>/=7 Tesla) permits images to be obtained with higher resolution and/or decreased scan time compared to scanning at 1.5/3T. In this small feasibility study, we show high measurement precision for subregional trabecular bone micro-architectural analysis performed on 7T knee MR images. The results provide further support for the use of trabecular bone measures as biomarkers in clinical studies of bone disorders

Non-human primates are often used as preclinical model systems for (mostly diffuse or multi-focal) neurological disorders and their experimental treatment. Due to cost considerations, such studies frequently utilize non-destructive imaging modalities, MRI and proton MR spectroscopy ((1) H MRS). Cost may explain why the inter- and intra-animal reproducibility of the (1) H MRS observed brain metabolites, are not reported. To this end, we performed test-retest three-dimensional brain (1) H MRS in five healthy rhesus macaques at 3 T. Spectra were acquired from 224 isotropic (0.5 cm)(3) = 125 muL voxels, over 28 cm(3) ( approximately 35%) of the brain, then individually phased, frequency aligned and summed into a spectrum representative of the entire volume of interest. This dramatically increases the metabolites' signal-to-noise ratios, while maintaining the (narrow) voxel linewidth. The results show that the average N-acetylaspartate, creatine, choline, and myo-inositol concentrations in the macaque brain are: 7.7 +/- 0.5, 7.0 +/- 0.5, 1.2 +/- 0.1 and 4.0 +/- 0.6 mM/g wet weight (mean +/- standard deviation). Their inter-animal coefficients of variation (CV) are 4%, 4%, 6%, and 15%; and the longitudinal (intra-animal) CVs are lower still: 4%, 5%, 5%, and 4%, much better than the 22%, 33%, 36%, and 45% intra-voxel CVs, demonstrating the advantage of the approach and its utility for preclinical studies of diffuse neurological diseases in rhesus macaques. Magn Reson Med, 2011. (c) 2011 Wiley-Liss, Inc

AIM: To compare image quality and lesion detection in the liver using magnetic resonance imaging (MRI) at 3T between T2-weighted imaging using a standard rectilinear k-space trajectory (standard T2WI) and using the BLADE technique (BLADE-T2WI), a technique that employs periodically rotated overlapping parallel lines with enhanced reconstruction for motion correction. MATERIALS AND METHODS: Twenty-eight consecutive patients who underwent MRI examination of the liver at 3T including standard T2WI and BLADE-T2WI, both performed using multiple breath-holds, comprised the study cohort. Images were reviewed in consensus by two radiologists during separate sessions for a number of measures regarding artefacts and image quality. These two readers also assessed the two image sets for the presence of liver lesions and measured liver-to-lesion contrast. Binary logistic regression for correlated data was used to compare the sequences in terms of sensitivity and positive predictive value (PPV) for lesion detection. RESULTS: BLADE-T2WI received significantly higher scores than did standard T2WI for in-plane respiratory motion (p=0.0195), other ghosting artefacts (p<0.0001), sharpness of the liver edge (p=0.0004), sharpness of intra-hepatic vessels (p<0.0001), flow signal suppression (p<0.0001), and overall image quality (p<0.0001). There was a non-significant trend toward improved B(1)-inhomogeneity artefact with BLADE-T2WI (p=0.0571). There was no difference in through-plane respiratory motion (p=0.6836). BLADE-T2WI demonstrated a significant improvement in PPV for lesion detection (p=0.0129) as well as in liver-to-lesion contrast (p=0.0054). There was no difference regarding lesion sensitivity (p=1.0). CONCLUSIONS: Use of the BLADE technique for T2-weighted MRI of the liver at 3T may lead to a significant improvement in image artefacts and improved PPV for lesion detection

PURPOSE: To assess the accuracy of glomerular filtration rate (GFR) measurements obtained with low-contrast agent dose dynamic contrast material-enhanced magnetic resonance (MR) renography in patients with liver cirrhosis who underwent routine liver MR imaging, with urinary clearance of technetium 99m ((99m)Tc) pentetic acid (DTPA) as the reference standard. MATERIALS AND METHODS: This HIPAA-compliant study was institutional review board approved. Written informed patient consent was obtained. Twenty patients with cirrhosis (14 men, six women; age range, 41-70 years; mean age, 54.6 years) who were scheduled for routine 1.5-T liver MR examinations to screen for hepatocellular carcinoma during a 6-month period were prospectively included. Five-minute MR renography with a 3-mL dose of gadoteridol was performed instead of a routine test-dose timing examination. The GFR was estimated at MR imaging with use of two kinetic models. In one model, only the signal intensities in the aorta and kidney parenchyma were considered, and in the other, renal cortical and medullary signal intensities were treated separately. The GFR was also calculated by using serum creatinine levels according to the Cockcroft-Gault and modification of diet in renal disease (MDRD) formulas. All patients underwent a (99m)Tc-DTPA urinary clearance examination on the same day to obtain a reference GFR measurement. The accuracies of all MR- and creatinine-based GFR estimations were compared by using Wilcoxon signed rank tests. RESULTS: The mean reference GFR, based on (99m)Tc-DTPA clearance, was 74.9 mL/min/1.73 m(2) +/- 27.7 (standard deviation) (range, 10.3-120.7 mL/min/1.73 m(2)). With both kinetic models, 95% of MR-based GFRs were within 30% of the reference values, whereas only 40% and 60% of Cockcroft-Gault- and MDRD-based GFRs, respectively, were within this range. MR-based GFR estimates were significantly more accurate than creatinine level-based estimates (P < .001). CONCLUSION: GFR assessment with MR imaging, which outperformed the Cockcroft-Gault and MDRD formulas, adds less than 10 minutes of table time to a clinically indicated liver MR examination without ionizing radiation. Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101338/-/DC1

OBJECTIVE: The purpose of this article is to correlate clinicopathologic and MRI parameters with the presence of microvascular invasion at histopathologic examination in patients with hepatocellular carcinoma (HCC) who are undergoing liver transplantation. MATERIALS AND METHODS: In this retrospective single-center study, we assessed 60 patients (47 men and 13 women; mean age, 58 years) with HCC who underwent liver transplantation and pretransplant MRI (performed within 90 days before liver transplantation). Two observers analyzed the following tumor parameters in consensus: number, size, T1 and T2 signal intensity, margins, presence of capsule or pseudocapsule, distance to closest vessel, distance to liver capsule, and quantitative tumor enhancement. The size and number of HCCs, tumor differentiation, and the presence or absence of microvascular invasion were determined at histopathologic examination. Odds ratios (ORs) were calculated and logistic regression analysis was performed to assess the utility of these clinicopathologic and imaging parameters for predicting microvascular invasion. RESULTS: None of the clinical parameters or morphologic and enhancement MRI features of HCC was predictive of microvascular invasion. Tumor multifocality, on both MRI and pathologic examination, was the only variable that predicted microvascular invasion (OR = 2.43 and p = 0.013 for MRI; OR = 1.94 and p = 0.013 for pathologic examination). The presence of three or more tumors on MRI and four or more tumors at pathologic examination had high specificity (88.2% and 91.2%, respectively) for the prediction of microvascular invasion. CONCLUSION: Tumor multifocality on MRI was the only parameter that correlated significantly with microvascular invasion. All other MRI tumor characteristics failed to predict microvascular invasion

OBJECTIVE: The purpose of this study was to assess the possible clinical significance of bladder urine T1 hyperintensity based upon comparison with urinalysis findings, using a cohort of patients who underwent prostate MRI and urinalysis at a similar point in time during preoperative work-up. METHODS: We identified 56 patients who underwent prostatectomy at our institution who obtained prostate MRI and urinalysis within 1 day of each other preoperatively. A control group of 160 consecutive adult men who underwent pelvic MRI during the same time period for other indications was also identified. Two radiologists independently and in consensus reviewed the T1-weighted images to assess the frequency of bladder urine T1 hyperintensity in both groups. The urinalyses in the 56 men undergoing prostatectomy were reviewed, with the results compared between patients with and without bladder urine T1 hyperintensity. RESULTS: Four (7.1%) of 56 men with prostate cancer exhibited T1 hyperintense bladder urine, compared with six (3.8%) of 160 patients exhibiting this finding in the control group (P=.288). Of the four prostate cancer patients with this finding, all exhibited a normal urinalysis. An abnormal urinalysis was identified for four of the prostate cancer patients, all of whom exhibited normal urine T1 signal intensity. CONCLUSION: Bladder urine T1 hyperintensity may be seen occasionally in patients with prostate cancer but is not associated with abnormal urinalysis and therefore should not be regarded as a sign of acute urinary pathology

OBJECTIVE: Published cardiac CT angiography (CTA) reference measurements for the cardiac chambers, aorta, and pulmonary artery (PA) are incomplete and compromised by study population, coronary artery disease (CAD), or its risk factors. The purpose of our study was to establish sex-specific normalized ranges of cardiac chamber size, wall thickness, ejection fraction (EF), and aorta and PA diameter on cardiac CTA in a population without CAD or its risk factors. MATERIALS AND METHODS: Seventy-six patients (38 men and 38 women) without known diabetes; hypertension; smoking history; or evidence of structural heart, vascular, or coronary artery diseases underwent 64-MDCTA. Obtained left atrial (LA) size, left ventricular (LV) volumes, LV wall thickness, thoracic aorta, and PA diameter measurements were normalized to body surface area (BSA). RESULTS: There were statistically significant differences noted between men and women for all measured left-sided heart and great vessel measurements. After normalization to BSA, only chamber dimensions and ascending aorta and left PA sizes remained significantly different. Selected normalized measurements for men versus women, respectively, include LA area, 10.6 +/- 2.1 versus 12.3 +/- 2.1 cm(2)/m(2); LV end-diastolic size, 72.4 +/- 15.1 versus 60.9 +/- 13.3 mL/m(2); EF, 67% +/- 7% versus 72% +/- 8%; aortic sinus, 1.6 +/- 0.2 versus 1.7 +/- 0.2 cm/m(2); ascending aorta, 1.4 +/- 0.2 versus 1.6 +/- 0.2 cm/m(2); descending aorta, 1.1 +/- 0.1 versus 1.2 +/- 0.1 cm/m2; main PA, 1.3 +/- 0.1 versus 1.4 +/- 0.1 cm/m(2); right PA, 1.1 +/- 0.1 versus 1.1 +/- 0.2 cm/m(2); and left PA, 1.0 +/- 0.1 versus 1.1 +/- 0.1 cm/m(2). CONCLUSION: Cardiac CTA measurements of the left cardiac chambers, thoracic aorta, and pulmonary arteries were established for a population without CAD or its risk factors

OBJECTIVES: To determine whether significant differences in cochlear implant (CI) performance exist between older and younger CI recipients. DESIGN: Retrospective comparison of audiometric data. SETTING: University hospital center. PARTICIPANTS: Sixty participants who received CIs at age 70 and older and 48 younger adults implanted between age 18 and 69. MEASUREMENTS: Speech outcome scores (Consonant-Nucleus-Consonant words and phonemes and City University of New York Sentence test in quiet and noise). RESULTS: Older participants show significant improvement in speech perception scores after implantation. Although on average they do not perform as well as younger adults, this difference correlates with duration of deafness rather than age. In contrast to younger adults, significant differences in CI performance are seen in older recipients depending on the side of implantation, with those implanted on the right performing better than those implanted on the left. CONCLUSION: Postlingually deafened older adults obtained significant speech perception benefits from CIs, although differences in speech outcomes were seen between younger recipients and those implanted after age 70. In older adults considering CIs, hearing benefits appear greater if they are implanted in the right ear