Faculty Bibliography

PURPOSE:: To assess added value of a new time-resolved technique with temporal interpolation and stochastic spiral trajectory through k-space and parallel imaging (TR-MRA) to conventional bolus chase MRA (BC-MRA) for infragenual peripheral artery evaluation. MATERIALS AND METHODS:: An institutional review board-approved retrospective review of peripheral arterial disease patients was performed. Infragenual TR-MRA and BC-MRA were performed in 26 patients over four months. Two readers individually assessed image quality, diagnostic confidence, and stenosis severity and length in 13 defined below knee segments, first with BC-MRA alone, and then with a combined BC-MRA and TR-MRA reading (BC+TR-MRA). Perceived contribution of TR-MRA was rated by each reader. The reference standard was a consensus reading of both sequences. Catheter angiographic (CA) correlation was available in 6 patients. RESULTS:: A total of 646 infragenual segments in 51 extremities were evaluated. Image quality and diagnostic confidence were superior for BC+TR-MRA compared with BC-MRA alone (P < 0.001). Adding TR-MRA improved sensitivity (85.7% versus 80.7%; P < 0.05) and diagnostic accuracy (88.1% versus 85.4%; P < 0.05) for hemodynamically significant stenosis. Venous contamination (0% versus 13.1% segments) and motion (0.9% versus 8.0%) were decreased for BC+TR-MRA versus BC-MRA alone, P < 0.01. For BC+TR-MRA, TR-MRA was rated more useful than BC-MRA in 30/51 legs (58.8%). TR-MRA identified retrograde flow in 5 segments. Where available, there was high concordance between CA and BC+TR-MRA (91.6%) for stenosis. CONCLUSION:: Adding TR-MRA with temporal interpolation and stochastic spiral trajectories to bolus chase MRA improves image quality, diagnostic confidence and accuracy. It provides hemodynamic information and minimizes venous contamination and patient motion. J. Magn. Reson. Imaging 2010;31:663-672. (c) 2010 Wiley-Liss, Inc

We compared image quality and diagnostic accuracy of a noncontrast 3-dimensional magnetic resonance angiography (NC-MRA) technique (balanced steady-state free-precession sequence) to contrast-enhanced MRA (CE-MRA) for evaluation of thoracic aortic disease.The CE-MRA provides 3-dimensional high-resolution images of the thoracic aorta that are important in the evaluation of patients with aortic disease. However, recent concerns with the potential nephrotoxic effects of gadolinium contrast medium limit the application of CE-MRA for patients who have significant renal insufficiency.Twenty-one patients (mean age, 51 yr; 18 men) who underwent NC-MRA and CE-MRA for evaluation of thoracic aortic disease were retrospectively identified. Data sets were reviewed by 2 readers who were blinded to the patients' information. The thoracic aorta was divided into 5 segments. Image quality and reader confidence for diagnosis of aortic pathology were rated on 5-point scales. The Wilcoxon matched-pairs signed rank test and the Student t test were used for comparisons.The NC-MRA identified all pathologic findings with 100% diagnostic accuracy and similar reader confidence, when compared with CE-MRA. Although overall image quality was not significantly different, superior image quality was observed at the aortic root (4.4 +/- 0.8 vs 3.2 +/- 0.9, P <0.0005) and ascending aorta (4.1 +/- 1 vs 3.7 +/- 0.9, P=0.05) respectively.In conclusion, NC-MRA is a useful alternative for evaluation and follow-up of thoracic aortic disease, especially for patients with poor intravenous access or contraindications to gadolinium use

Neuro-axonal degeneration occurs progressively from the onset of multiple sclerosis and is thought to be a significant cause of increasing clinical disability. Several histopathological studies of multiple sclerosis and experimental autoimmune encephalomyelitis have shown that the accumulation of sodium in axons can promote reverse action of the sodium/calcium exchanger that, in turn, leads to a lethal overload in intra-axonal calcium. We hypothesized that sodium magnetic resonance imaging would provide an indicator of cellular and metabolic integrity and ion homeostasis in patients with multiple sclerosis. Using a three-dimensional radial gradient-echo sequence with short echo time, we performed sodium magnetic resonance imaging at 3 T in 17 patients with relapsing-remitting multiple sclerosis and in 13 normal subjects. The absolute total tissue sodium concentration was measured in lesions and in several areas of normal-appearing white and grey matter in patients, and corresponding areas of white and grey matter in controls. A mixed model analysis of covariance was performed to compare regional tissue sodium concentration levels in patients and controls. Spearman correlations were used to determine the association of regional tissue sodium concentration levels in T(2)- and T(1)-weighted lesions with measures of normalized whole brain and grey and white matter volumes, and with expanded disability status scale scores. In patients, tissue sodium concentration levels were found to be elevated in acute and chronic lesions compared to areas of normal-appearing white matter (P < 0.0001). The tissue sodium concentration levels in areas of normal-appearing white matter were significantly higher than those in corresponding white matter regions in healthy controls (P < 0.0001). The tissue sodium concentration value averaged over lesions and over regions of normal-appearing white and grey matter was positively associated with T(2)-weighted (P < or = 0.001 for all) and T(1)-weighted (P < or = 0.006 for all) lesion volumes. In patients, only the tissue sodium concentration value averaged over regions of normal-appearing grey matter was negatively associated with the normalized grey matter volume (P = 0.0009). Finally, the expanded disability status scale score showed a mild, positive association with the mean tissue sodium concentration value in chronic lesions (P = 0.002), in regions of normal-appearing white matter (P = 0.004) and normal-appearing grey matter (P = 0.002). This study shows the feasibility of using in vivo sodium magnetic resonance imaging at 3 T in patients with multiple sclerosis. Our findings suggest that the abnormal values of the tissue sodium concentration in patients with relapsing-remitting multiple sclerosis might reflect changes in cellular composition of the lesions and/or changes in cellular and metabolic integrity. Sodium magnetic resonance imaging has the potential to provide insight into the pathophysiological mechanisms of tissue injury when correlation with histopathology becomes available

OBJECTIVE: The purpose of this study was to determine the diagnostic performance of chemical shift imaging, compared with that of single-echo T2*-weighted imaging, for hepatic iron quantification in patients with liver disease, and to examine the confounding effect of steatosis. MATERIALS AND METHODS: Sixty-three patients who underwent liver MRI and who had concomitant liver histopathologic analysis were retrospectively assessed. Chemical shift imaging and T2*-weighted imaging (n = 49) of the liver were reviewed by two independent observers. An iron index for each sequence (I(Fe-CSI) and I(Fe-T2*), respectively) was correlated with pathologic iron grade (0-4). Receiver operating characteristic curve analysis was performed to assess the accuracy of both sequences for the diagnosis of iron deposition (grades >or= 1, >or= 2, and >or= 3), and the impact of steatosis on accuracy was evaluated. RESULTS: Forty-seven (74.6%) patients had hepatic siderosis. There was a significant correlation between both I(Fe-CSI) and I(Fe-T2*) with pathologic iron grade (r = 0.65 and -0.61, respectively; p < 0.0001 for both). I(Fe-CSI) and I(Fe-T2*) were significantly higher or lower in iron grades 2-4 versus grades 0-1 and in grades 3-4 versus grades 0-2 (p < 0.001). Area under the curve values for detecting iron grade >or= 1, >or= 2, and >or= 3 were 0.75, 0.88, and 0.90 for I(Fe-CSI) and 0.72, 0.81, and 0.98 for I(Fe-T2*). Accuracy was lower for both sequences in steatotic patients for detection of iron grades >or= 1 and >or= 2, without reaching significance. CONCLUSION: Routine chemical shift imaging and single-echo T2*-weighted imaging have excellent diagnostic performance for detection of significant hepatic siderosis (grade >or= 2). Concomitant steatosis lowers the diagnostic performance of both sequences without reaching significance

OBJECTIVE: The full diagnostic value of diffusion-weighted (DW) MRI in the evaluation of liver metastases remains uncertain. The aim of the present study was to assess the diagnostic accuracy of DW-MRI and contrast-enhanced MRI (CE-MRI) using extracellular gadolinium chelates, with the reference standard established by consensus interpretation of confirmatory imaging and histopathologic data. METHODS: MR examinations of 51 patients with extrahepatic malignancies were retrospectively reviewed by two independent observers who assessed DW-MRI and CE-MRI for detection of liver metastases. RESULTS: By reference standard, 93 liver lesions (49 metastases and 44 benign lesions) were identified in 27 patients, 11 patients had no liver lesions, and 13 patients had innumerable metastatic and/or benign lesions. There was no difference in diagnostic performance between the two methods for either observer for the diagnosis of metastatic lesions per patient. For per-lesion analysis, sensitivity of DW-MRI was equivalent to CE-MRI for observer 1 (67.3% vs. 63.3%, p = 0.67), but lower for observer 2 (65.3% vs. 83.7%, p = 0.007). By pooling data from both observers, the sensitivity of DW-MRI was 66.3% (65/98) and 73.5% (72/98) for CE-MRI, with no significant difference (p = 0.171). CONCLUSION: DW-MRI is a reasonable alternative to CE-MRI for the detection of liver metastases

PURPOSE: To assess the value of quantitative T2 signal intensity (SI) and apparent diffusion coefficient (ADC) to differentiate prostate cancer from post-biopsy hemorrhage, using prostatectomy as the reference. MATERIALS AND METHODS: Forty-five men with prostate cancer underwent prostate magnetic resonance imaging (MRI), including axial T1-weighted imaging (T1WI), T2WI, and single-shot echo-planar image (SS EPI) diffusion-weighted imaging. Two observers measured, in consensus, normalized T2 signal intensity (SI) (nT2, relative to muscle T2 SI), ADC, and normalized ADC (nADC, relative to urine ADC) on peripheral zone (PZ) tumors, benign PZ hemorrhage, and non-hemorrhagic benign PZ. Tumor maps from prostatectomy were used as the reference. Mixed model analysis of variance was performed to compare parameters among the three tissue classes, and Pearson's correlation coefficient was utilized to assess correlation between parameters and tumor size and Gleason score. Receiver-operating characteristic (ROC)-curve analysis was used to determine the performance of nT2, ADC, and nADC for diagnosis of prostate cancer. RESULTS: nT2, ADC, and nADC were significantly lower in tumor compared with hemorrhagic and non-hemorrhagic benign PZ (P < 0.0001). There was a weak but significant correlation between ADC and Gleason score (r = -0.30, P = 0.0119), and between ADC and tumor size (r = -0.40, P = 0.0027), whereas there was no correlation between nT2 and Gleason score and tumor size. The areas under the curve to distinguish tumor from benign hemorrhagic and non-hemorrhagic PZ were 0.97, 0.96, and 0.933 for nT2, ADC, and nADC, respectively. CONCLUSION: Quantitative T2 SI and ADC/nADC values may be used to reliably distinguish prostate cancer from post-biopsy hemorrhage

PURPOSE: To determine whether liver metastases conspicuity is improved at 80 kVp when compared with weighted average (WA) simulated 120 kVp data using dual source dual energy CT. METHODS: A total of 11 patients with 44 hypo-vascular liver metastases underwent contrast enhanced Dual Energy CT (DECT). In all cases the subject's abdominal diameter measured <or=35 cm. Data were reconstructed as a WA of the 140 kVp and 80 kVp acquisitions (simulating 120 kVp) and as a pure 80 kVp data set. A region of interest cursor was placed within the metastasis and adjacent normal parenchyma and attenuation differences and contrast to noise ratios (CNR) were calculated for the metastases at 80 kVp and on the WA acquisition. A mixed model 2-way analysis of variance was used to test whether the attenuation difference between metastases and normal liver was higher at 80 kVp than 120 kVp. An exact Wilcoxon matched-pairs signed rank test was used to test whether CNR was higher at 80 kVp. Cases were retrospectively reviewed to determine whether lesions could be seen on only one or both data sets. As the 80 kVp tube has a smaller detector than the 140 kVp tube, we also noted whether any of the liver lesions were not included on the 80 kVp dataset. Two radiologists in consensus evaluated the 80 kVp data and WA data and subjectively rated hepatic metastases conspicuity on a 4 point scale; with 1 being excellent, 2 good, 3 poor, and 4 not seen. RESULTS: The mean size of the metastases was 2.6 cm. The mean +/- SD of the attenuation difference between the metastases and the normal liver was 78.37 +/- 24.6 at 80 kVp and 56.89 +/- 17.9 at 120 kVp. The mean difference in attenuation was significantly higher at 80 kVp (P < 0.001). In 2 cases, a metastases was only seen at 80 kVp. The difference between 80 and 120 kVp in terms of CNR was statistically significant (P = 0.042). In one patient, 11 lesions were not included in the smaller field of view of the 80 kVp detector. The conspicuity scores were rated as significantly better at 80 kv than at 120 kVp (P < 0.0001). CONCLUSION: When compared with 120 kVp data, pure 80 kVp data acquired from a dual source dual energy MDCT scanner demonstrates greater attenuation differences and improved contrast to noise between metastatic disease and normal liver

BACKGROUND: Although adolescent major depressive disorder (MDD) is acknowledged to be a heterogeneous disorder, no studies have reported on biological correlates of its clinical subgroups. This study addresses this issue by examining whether adolescent MDD with and without melancholic features (M-MDD and NonM-MDD) have distinct biological features in the kynurenine pathway (KP). The KP is initiated by pro-inflammatory cytokines via induction of the enzyme indoleamine 2,3-dioxygenase (IDO), which degrades tryptophan (TRP) into kynurenine (KYN). KYN is further metabolized into neurotoxins linked to neuronal dysfunction in MDD. Hypotheses were that, compared to healthy controls and to NonM-MDD adolescents, adolescents with M-MDD would exhibit: (i) increased activation of the KP [i.e., increased KYN and KYN/TRP (reflecting IDO activity)]; (ii) greater neurotoxic loads [i.e., increased 3-hydroxyanthranilic acid (3-HAA, neurotoxin) and 3-HAA/KYN (reflecting production of neurotoxins)]; and (iii) decreased TRP. We also examined relationships between severity of MDD and KP metabolites. METHODS: Subjects were 20 adolescents with M-MDD, 30 adolescents with NonM-MDD, and 22 healthy adolescents. MDD episode duration had to be >or= 6 weeks and Children's Depression Rating Scale-Revised (CDRS-R) scores were >or= 36. Blood samples were collected at AM after an overnight fast and analyzed using high-performance liquid chromatography. Group contrasts relied on analysis of covariance based on ranks, adjusted for age, gender, and CDRS-R scores. Analyses were repeated excluding medicated patients. Fisher's protected least significant difference was used for multiple comparisons. RESULTS: As hypothesized, KYN/TRP ratios were elevated and TRP concentrations were reduced in adolescents with M-MDD compared to NonM-MDD adolescents (p = .001 and .006, respectively) and to healthy controls (p = .008 and .022, respectively). These findings remained significant when medicated patients were excluded from the analyses. Significant correlations were obtained exclusively in the M-MDD group between KYN and 3-HAA/KYN and CDRS-R. CONCLUSIONS: Findings support the notion that adolescent M-MDD may represent a biologically distinct clinical syndrome

OBJECTIVE: To assess the relationship between T2 values of femorotibial cartilage and knee alignment in patients with clinical symptoms of medial osteoarthritis (OA). METHODS: Twenty-four patients (mean age +/- standard deviation, 62.5 +/- 9.9 years) with clinical symptoms of medial knee OA, 12 with varus and 12 with valgus alignment of the femorotibial joint, were investigated on 3T MR using a 2D multi-echo spin echo (MESE) sequence for T2 mapping. Analysis of covariance, Spearman correlation coefficients, exact Mann-Whitney tests, and Fisher's exact tests were used for statistical analysis. RESULTS: Overall the T2 values of cartilage in the medial compartment (median +/- interquartile-range, 49.44 +/- 6.58) were significantly higher (P = 0.0043) than those in the lateral compartment (47.15 +/- 6.87). Patients with varus alignment (50.83 +/- 6.30 ms) had significantly higher T2 values of cartilage (P < 0.0001) than patients with valgus alignment (46.20 +/- 6.00 ms). No statistically significant association between the T2 values of cartilage (in either location) and the Kellgren Lawrence score was found in the varus or in the valgus group. CONCLUSION: T2 measurements were increased in medial knee OA patients with varus alignment, adding support to the theory of an association of OA and joint alignment

OBJECTIVE: The purpose of this article is to review imaging of the rotator interval, an anatomically complex region in the shoulder that plays an important role in the normal function of the shoulder joint. The rotator interval can be difficult to evaluate by imaging, and it is not routinely evaluated arthroscopically unless the clinical examination or imaging findings suggest an abnormality of the rotator interval. Rotator interval pathology is implicated in glenohumeral instability, biceps instability and adhesive capsulitis-entities which remain a challenge to diagnose and treat. CONCLUSION: Imaging can play an important role in increasing suspicion for injury to the rotator interval so that this region can be evaluated and appropriate treatment can be initiated