Detection of soft-tissue abscess: Comparison of diffusion-weighted imaging to contrast-enhanced MRI.

PURPOSE: To compare the diagnostic performances of diffusion-weighted imaging (DWI)-combined magnetic resonance imaging (MRI) performed without intravenous contrast material with gadolinium contrast material-enhanced (CE) MRI for diagnosing soft-tissue abscesses. MATERIALS AND METHODS: In all, 119 patients (mean age: 56 years) with skin and soft-tissue infection who underwent contrast-enhanced MRI with DWI (b = 0-800) were included. Two readers independently reviewed both image sets-nonenhanced conventional MR images (NECI)+DWI, and NECI+contrast enhanced fat-suppressed T1 -weighted imaging (CEFST1 )-for the presence of abscess. To compare the diagnostic performance for diagnosing abscess between NECI+DWI, and NECI+CEFST1 , McNemar tests for sensitivity and specificity, and areas under the receiver-operating characteristic curves (AUC) analyses, were performed. Interobserver agreements (κ) were calculated for each image set. RESULTS: Forty of 119 patients were confirmed with abscess. Sensitivity and specificity were 90.0% and 88.6% for NECI+DWI, and 82.5% and 89.9% for NECI+CEFST1 in reader 1, whereas 77.5% and 88.6% for NECI+DWI, and 80.0% and 84.8% for NECI+CEFST1 in reader 2, respectively. There was no significant difference in sensitivities and specificities between NECI+DWI and NECI+CEFST1 (reader 1: P = 0.453, P = 0.999, reader 2: P = 0.999, P = 0.453, respectively). Likewise, AUC analyses demonstrated no significant difference between NECI+DWI and NECI+CEFST1 (P = 0.53 in reader 1, P = 0.97 in reader 2). Interobserver agreement between the two readers was substantial in both image sets: 0.80 (NECI+DWI), and 0.76 (NECI+CEFST1 ). CONCLUSION: Noncontrast-enhanced MRI with DWI has comparable diagnostic performance to contrast-enhanced MRI for diagnosing soft-tissue abscesses. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:60-68.

Differentiation of focal indeterminate marrow abnormalities with multiparametric MRI.

PURPOSE: To explore magnetic resonance imaging (MRI) parameters from intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI), multiecho Dixon imaging (ME-Dixon), and dynamic contrast-enhanced imaging (DCE) for differentiating focal indeterminate marrow abnormalities MATERIALS AND METHODS: Forty-two patients with 14 benign and 28 malignant focal marrow abnormalities were included. The following were independently analyzed by two readers: signal intensity (SI), contour, and margin on conventional MR images; SI on b-800 images (SIb-800 ), apparent diffusion coefficient (ADC), IVIM parameters (Dslow, Dfast , and f), fat fraction (Ff), and DCE parameters (time-to-signal intensity curve pattern, iAUC, Ktrans , kep , and ve ). The MR characteristics and parameters from benign and malignant lesions were compared with a chi-squared test and the Mann-Whitney U-test, respectively. The area under receiver operating characteristic (ROC) curves (AUC) of each sequence were also compared. Interobserver agreements were assessed with Cohen's κ, and intraclass correlation coefficient (ICC). RESULTS: ADC, Dslow , and Ff demonstrated a significant difference between benign and malignant marrow abnormalities for both readers (P < 0.001). SIb-800 and perfusion-related parameters from IVIM-DWI and DCE were not significantly different between the two groups (P = 0.145, 0.439, and 0.337 for reader 1, P = 0.378, 0.368, and 0.343 for reader 2, respectively). The AUCs of ADC, Dslow , and Ff were significantly higher for differentiating indeterminate marrow abnormalities in both readers (P < 0.001). Interobserver agreements were substantial in SIb-800 , and ICCs were almost perfect for ADC, Dslow , f, and Ff, and substantial for iAUC, kep , Ktrans , ve , and Dfast . CONCLUSION: ADC, Dslow , and Ff may provide information for differentiating focal indeterminate abnormalities. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:49-60.

Characteristic location and growth patterns of functioning pituitary adenomas: correlation with histological distribution of hormone-secreting cells in the pituitary gland.

OBJECTIVE: To evaluate the correlation between the magnetic resonance imaging findings of functional pituitary adenomas and histological distribution of hormone-secreting cells in pituitary gland. METHODS: Forty-nine patients with pathologically confirmed functional micro and macro pituitary adenomas were retrospectively reviewed for its location and growth direction. RESULTS: Micro-prolactin, micro-adrenocorticotropic hormone (ACTH), and micro-growth hormone (GH) producing adenomas showed specific location (P-value <.01). Macro-GH and macro-thyroid-stimulating hormone producing adenomas showed specific growth direction (P-value <.05), whereas macro-prolactin and macro-ACTH producing adenomas did not. CONCLUSION: The functional pituitary microadenomas' location and macroadenomas' growth pattern correlate well with histological distribution of hormone-secreting cells in pituitary gland.