Faculty Bibliography

OBJECTIVE: The purpose of our study was to determine the findings at both static and dynamic MRI in women with a clinically suspected urethral abnormality. MATERIALS AND METHODS: MRI of the urethra was performed in 84 women with lower urinary tract symptoms using multiplanar T2-weighted turbo spin-echo and unenhanced and contrast-enhanced gradient-echo sequences. A dynamic true fast imaging with steady-state free precession sequence was performed during straining in the sagittal plane. Images were evaluated by two radiologists for urethral pathology and pelvic organ prolapse. MRI findings were correlated with clinical symptoms using the Fisher's exact and Mann-Whitney tests. RESULTS: Urethral abnormalities were found in 10 of 84 patients (11.9%), including two urethral diverticula, five Skene's gland cysts or abscesses, and three periurethral cysts. Thirty-three patients (39.3%) were diagnosed with pelvic organ prolapse, of whom 29 (87.9%) were diagnosed exclusively on dynamic imaging. In 29 of 33 patients with prolapse (87.9%), the urethra was structurally normal. MRI showed 13 cystoceles and 17 cases of urethral hypermobility not detected on physical examination. Patients with a greater number of vaginal deliveries, stress urinary incontinence, frequency of voiding, and voiding difficulty were statistically more likely to have anterior compartment prolapse (p < 0.05). CONCLUSION: Including a dynamic sequence permits both structural and functional evaluation of the urethra, which may be of added value in women with lower urinary tract symptoms. Dynamic MRI allows detection of pelvic organ prolapse that may not be evident on conventional static sequences

BACKGROUND: In accordance with ALARA, minimizing radiation exposure associated with voiding cystourethrograms (VCUG) is of critical importance. Advances in fluoroscopic technology might help achieve this goal. OBJECTIVE: To determine the efficacy of fluoroscopic image capture compared to conventional digital radiographic spot (DRS) images in voiding cystourethrograms (VCUG) for the evaluation of vesicoureteral reflux (VUR) in children. MATERIALS AND METHODS: The study was a retrospective review of 65 VCUG examinations (130 kidney/ureter units). Each examination consisted of fluoroscopically captured spot (FCS) images and the corresponding DRS images. Each set of images was evaluated by three pediatric radiologists for the diagnosis of VUR for a total of 390 kidney/ureter units reviewed. Using the DRS image set as the reference standard, the efficacy of the FCS images for diagnosing reflux was determined. RESULTS: The diagnostic accuracy of the FCS images in terms of the binary characterization of reflux as negative or positive was 97.2% (379/390). The sensitivity of the FCS images was 92.6% (88/95); the specificity of the FCS images was 98.6% (291/295). CONCLUSION: Fluoroscopically captured images are adequate in documenting absence of VUR on VCUG examinations, obviating the need for radiographic spot images and resulting in reduction in radiation exposure

BACKGROUND AND PURPOSE: MR imaging can measure tissue perfusion and the integrity of the blood-brain barrier. We hypothesize that a combined measure of cerebral blood volume and vascular permeability using vascular-space occupancy (VASO) MR imaging, a recently developed imaging technique, is of diagnostic value for predicting tumor grade. MATERIALS AND METHODS: Thirty-nine patients (9 World Health Organization [WHO] grade II, 20 grade III, and 10 grade IV as determined by histopathologic assessment) were examined using VASO MR imaging, and regions-of-interest analysis was performed in tumoral regions, as well as in regions contralateral to the tumor. A Mann-Whitney test was conducted on the resulting VASO indices for a pairwise comparison across tumor grades. Nominal logistic regression was used to evaluate the use of VASO parameters for predicting group membership (by the percentage of correct classifications). RESULTS: The ratio between tumor side and contralateral side, VASO(Ratio), showed significant differences in all 3 of the pairwise comparisons (P < .01). VASO values in the tumoral regions, VASO(Tumor), showed significant difference between grade II and III and between II and IV but not between III and IV. Both VASO(Tumor) and VASO(Ratio) were found to be significant predictors of tumor grade, giving diagnostic accuracies of 66.7% and 71.8%, respectively. When testing to discriminate grade II tumors from higher grade tumors, the areas under the receiver operating characteristic curve were found to be 0.974 and 0.985 for VASO(Tumor) and VASO(Ratio), respectively. CONCLUSION: VASO MR imaging can be used for noninvasive tumor grade prediction based on cerebral blood volume and vascular permeability. VASO is more effective in separating WHO grade II from higher grades than in separating grade III from grade IV

BACKGROUND AND PURPOSE: Time-resolved MR angiography (MRA) offers the combined advantage of large anatomic coverage and hemodynamic flow information. We applied parallel imaging and time-resolved imaging with stochastic trajectories (TWIST), which uses a spiral trajectory to undersample k-space, to perform time-resolved MRA of the extracranial internal carotid arteries and compare it to time-of-flight (TOF) and high-resolution contrast-enhanced (HR) MRA. MATERIALS AND METHODS: A retrospective review of 31 patients who underwent carotid MRA at 1.5T using TOF, time-resolved and HR MRA was performed. Images were evaluated for the presence and degree of ICA stenosis, reader confidence, and number of pure arterial frames attained with the TWIST technique. RESULTS: With a consensus interpretation of all sequences as the reference standard, accuracy for identifying stenosis was 90.3% for TWIST MRA, compared with 96.0% and 88.7% for HR MRA and TOF MRA, respectively. HR MRA was significantly more accurate than the other techniques (P < .05). TWIST MRA yielded datasets with high in-plane spatial resolution and distinct arterial and venous phases. It provided dynamic information not otherwise available. Mean diagnostic confidence was satisfactory or greater for TWIST in all patients. CONCLUSION: The TWIST technique consistently obtained pure arterial phase images while providing dynamic information. It is rapid, uses a low dose of contrast, and may be useful in specific circumstances, such as in the acute stroke setting. However, it does not yet have spatial resolution comparable with standard contrast-enhanced MRA

The aim of the study was to compare the performance of Robust and Conventional neuropsychological norms in predicting clinical decline among healthy adults and in mild cognitive impairment (MCI). The authors developed Robust baseline cross sectional and longitudinal change norms from 113 healthy participants retaining a normal diagnosis for at least 4 years. Baseline Conventional norms were separately created for 256 similar healthy participants without follow-up. Conventional and Robust norms were tested in an independent cohort of longitudinally studied healthy (n=223), MCI (n=136), and Alzheimer's disease (AD, n=162) participants; 84 healthy participants declined to MCI or AD (NL-->DEC), and 44 MCI declined to AD (MCI-->AD). Compared to Conventional norms, baseline Robust norms correctly identified a higher proportion of NL-->DEC with impairment in delayed memory and attention-language domains. Both norms predicted decline from MCI-->AD. Change norms for delayed memory and attention-language significantly incremented baseline classification accuracies. These findings indicate that Robust norms improve identification of healthy individuals who will decline and may be useful for selecting at-risk participants for research studies and early interventions

Although cognitive impairment is common in multiple sclerosis (MS), its pathophysiology is still poorly understood. Abnormalities of cerebral blood flow (CBF) have long been acknowledged in MS and advances in perfusion magnetic resonance imaging (MRI) allow for their assessment in vivo. We investigated the relationship between regional perfusion changes and neuropsychological (NP) dysfunctions in patients with relapsing-remitting and primary-progressive MS. Absolute CBF, cerebral blood volume (CBV) and mean transit time were measured in 32 MS patients and 11 healthy controls using dynamic susceptibility contrast-enhanced T2(*)-weighted MRI. A comprehensive NP test battery was administered to all patients. A mixed model analysis of covariance was performed for group comparisons in terms of perfusion measures in normal-appearing white matter (NAWM) and deep gray matter (GM). Pearson's correlations were used to describe the association of perfusion metrics with NP Z-scores. CBF and CBV values were significantly decreased in both NAWM and deep GM in MS patients compared with controls (P=0.01). In all patients, deep GM CBF was significantly associated with Rey Complex Figure Test (RCFT)-Copy (r=0.5; P=0.001) and deep GM CBV and NAWM CBV were significantly associated with Color-Word Interference Inhibition Switching test (D-KEFSIS) (r=0.4; P=0.008 and r=0.4; P=0.02). However, the only associations that remained significant after Bonferroni correction were between deep GM CBF and RCFT-Copy (P=0.006), and deep GM CBV and D-KEFSIS (P=0.04). Our results suggest a role for tissue perfusion impairment in NP dysfunction in MS. Large-scale studies are needed to characterize better this association.Journal of Cerebral Blood Flow & Metabolism advance online publication, 2 May 2007; doi:10.1038/sj.jcbfm.9600504

Manganese-enhanced MRI (MEMRI) has been developed to image brain activity in small animals, including normal and genetically modified mice. Here, we report the use of a MEMRI-based statistical parametric mapping method to analyze sound-evoked activity in the mouse auditory midbrain, the inferior colliculus (IC). Acoustic stimuli with defined frequency and amplitude components were shown to activate and enhance neuronal ensembles in the IC. These IC activity patterns were analyzed quantitatively using voxel-based statistical comparisons between groups of mice with or without sound stimulation. Repetitive 40-kHz pure tone stimulation significantly enhanced ventral IC regions, which was confirmed in the statistical maps showing active regions whose volumes increased in direct proportion to the amplitude of the sound stimuli (65 dB, 77 dB, and 89 dB peak sound pressure level). The peak values of the activity-dependent MEMRI signal enhancement also increased from 7% to 20% for the sound amplitudes employed. These results demonstrate that MEMRI statistical mapping can be used to analyze both the 3D spatial patterns and the magnitude of activity evoked by sound stimuli carrying different energy. This represents a significant advance in the development of MEMRI for quantitative and unbiased analysis of brain function in the deep brain nuclei of mice

PURPOSE: To retrospectively compare diffusion-weighted (DW) magnetic resonance (MR) imaging with standard breath-hold T2-weighted MR imaging for focal liver lesion (FLL) detection and characterization, by using consensus evaluation and other findings as the reference standard. MATERIALS AND METHODS: Approval for this retrospective HIPAA-compliant study was obtained from the institutional review board; informed consent was waived. Fifty-three consecutive patients (30 men, 23 women; mean age, 60.7 years) with at least one FLL of 1 cm or greater in diameter were evaluated. Two independent observers reviewed DW (b values of 0, 50, and 500 sec/mm(2)) and T2-weighted images for FLL detection and characterization. Reference standard for diagnosis was obtained from consensus review by the two observers of DW, T2-weighted, and dynamic contrast material-enhanced images, pathologic data, and follow-up imaging results. Apparent diffusion coefficient (ADC) was measured for FLLs identified at consensus review. DW and T2-weighted images were compared for FLL detection and characterization by using a binary logistic regression model. Receiver operating characteristic curve analyses were conducted to evaluate the utility of ADC for diagnosis of malignancy. RESULTS: Two hundred eleven FLLs (136 malignant, 75 benign) were detected at consensus review. Overall detection rate (averaged for two observers) was significantly higher for DW (87.7%) versus T2-weighted (70.1%) imaging (P < .001). FLL characterization was not significantly different between DW (89.1%) and T2-weighted (86.8%) imaging (P = .51). ADCs of malignant FLLs were significantly lower than those of benign FLLs (P < .001). The area under the curve for diagnosis of malignancy was 0.839, with sensitivity of 74.2%, specificity of 77.3%, positive predictive value of 85.5%, negative predictive value of 62.3%, and accuracy of 75.3%, by using a threshold ADC of less than 1.60 x 10(-3) mm(2)/sec. CONCLUSION: DW MR imaging was better than standard breath-hold T2-weighted imaging for FLL detection and was equal to breath-hold T2-weighted imaging for FLL characterization