Comparison of Multi-Echo Dixon Methods with Volume Interpolated Breath-Hold Gradient Echo Magnetic Resonance Imaging in Fat-Signal Fraction Quantification of Paravertebral Muscle

OBJECTIVE: To assess whether multi-echo Dixon magnetic resonance (MR) imaging with simultaneous T2* estimation and correction yields more accurate fat-signal fraction (FF) measurement of the lumbar paravertebral muscles, in comparison with non-T2*-corrected two-echo Dixon or T2*-corrected three-echo Dixon, using the FF measurements from single-voxel MR spectroscopy as the reference standard. MATERIALS AND METHODS: Sixty patients with low back pain underwent MR imaging with a 1.5T scanner. FF mapping images automatically obtained using T2*-corrected Dixon technique with two (non-T2*-corrected), three, and six echoes, were compared with images from single-voxel MR spectroscopy at the paravertebral muscles on levels L4 through L5. FFs were measured directly by two radiologists, who independently drew the region of interest on the mapping images from the three sequences. RESULTS: A total of 117 spectroscopic measurements were performed either bilaterally (57 of 60 subjects) or unilaterally (3 of 60 subjects). The mean spectroscopic FF was 14.3 ± 11.7% (range, 1.9-63.7%). Interobserver agreement was excellent between the two radiologists. Lin's concordance correlation between the spectroscopic findings and all the imaging-based FFs were statistically significant (p < 0.001). FFs obtained from the T2*-corrected six-echo Dixon sequences showed a significantly better concordance with the spectroscopic data, with its concordance correlation coefficient being 0.99 and 0.98 (p < 0.001), as compared with two- or three-echo methods. CONCLUSION: T2*-corrected six-echo Dixon sequence would be a better option than two- or three-echo methods for noninvasive quantification of lumbar muscle fat quantification.ope

External validation of the RENAL nephrometry score nomogram for predicting high-grade renal cell carcinoma in solid, enhancing, and small renal masses

PURPOSE: To confirm predictive accuracies of the RENAL nephrometry score (RNS) nomogram for identifying malignancy and high-grade renal cell carcinoma (RCC) in an external cohort of small renal masses (SRMs). METHODS: A total of 1,129 patients who underwent extirpative renal surgery for solid and enhancing cT1 renal tumors between 2005 and 2012 at a single institution were included in the validation cohort. A single uro-radiologist utilized computed tomography image reconstruction to classify tumors according to the RNS. The area under the curve (AUC) and calibration plots were used to determine predictive accuracies of malignancy and high-grade models of the RNS nomogram. RESULTS: Malignant and high-grade tumors were identified in 1,012 (89.6%) and 389 (38.4%) patients with cT1 tumors, and in 658 (87.3%) and 215 (32.6%) patients with cT1a tumors, respectively. Predictive performances of the nomogram for malignancy and high-grade models revealed AUCs of 0.722 and 0.574 for cT1 tumors, and 0.727 and 0.495 for cT1a tumors, respectively. The predictive value of the malignancy model was comparable to that of the model-development cohort (AUC = 0.76); however, the predictive value of the high-grade model was inferior to that of the model-development cohort (AUC = 0.73). CONCLUSIONS: Unlike previous validation studies, we report inferior predictive performance of the RNS nomogram for discriminating high-grade RCC in solid and enhancing SRMs. This suggests that the RNS nomogram may be unreliable for preoperatively predicting high-grade RCC in SRMs, in which tumor size, the key determinant of high-grade RCC, is a limiting factor.ope

Prognostic impact of synchronous second primary malignancies on the overall survival of patients with metastatic prostate cancer

PURPOSE: We determined the prognostic impact of a synchronous second primary malignancy on overall survival in patients with metastatic prostate cancer. Identifying features that stratify the risk of overall survival is critical for judiciously applying definitive therapy. MATERIALS AND METHODS: We retrospectively analyzed the records of 582 consecutive patients with prostate cancer diagnosed with metastasis between May 7, 1998 and August 27, 2011. Patient age, body mass index, ECOG performance status, Charlson comorbidity index, prostate specific antigen, T and N stages, Gleason and ASA® scores, progression to castration resistant prostate cancer, prior local treatments and synchronous second primary malignancies at metastasis were assessed. A synchronous second primary malignancy was defined as a cytologically or histologically proven solid malignancy. Cox proportional hazards regression analysis was done to estimate overall survival by second primary type and evaluate predictive variables. RESULTS: A total of 164 patients (28.1%) had a synchronous second primary malignancy, of which colorectal (9.1%), stomach (7.3%) and lung (7.1%) cancers were the most prevalent types. During a median followup of 34.1 months patients without a synchronous second primary malignancy had a significantly higher overall survival rate than those with lung or stomach cancer. However, men without a second malignancy had outcomes comparable to those in men with colorectal cancer. Clinical stage T4 or greater, ASA score 1 or greater and lung or stomach cancer were independent predictors of overall mortality. CONCLUSIONS: A substantial proportion of patients with metastatic prostate cancer present with a synchronous second primary malignancy. Definitive therapy targeting prostate cancer may confer a limited survival benefit in patients with synchronous lung or stomach cancer.ope