Masao Yui

Improved arterial visibility using short-tau inversion-recovery (STIR) fat suppression in non-contrast-enhanced time–spatial labeling inversion pulse (Time-SLIP) renal MR angiography (MRA)

To evaluate whether short‐tau inversion‐recovery (STIR) fat suppression is worthwhile in non‐contrast‐enhanced respiration‐triggered free‐breathing time–spatial labeling inversion pulse (Time‐SLIP) renal magnetic resonance angiography (MRA) compared with chemical shift selective (CHESS) fat suppression.

Time-resolved three-dimensional magnetic resonance digital subtraction angiography without contrast material in the brain: Initial investigation

To evaluate a novel magnetic resonance (MR) angiography (MRA) of three‐dimensional (3D) MR digital subtraction angiography (MRDSA) without contrast material, which is essentially 3D true steady‐state free precession (SSFP) with selected inversion recovery (IR) pulse using multiple cardiac phase acquisitions with a short increment delay in the assessment of normal cranial arteries, as a feasibility study before clinical use.

Chemical Exchange Saturation Transfer MR Imaging: Preliminary Results for Differentiation of Malignant and Benign Thoracic Lesions

PURPOSE To prospectively evaluate the capability of amide proton transfer-weighted chemical exchange saturation transfer magnetic resonance (MR) imaging for characterization of thoracic lesions. MATERIALS AND METHODS The institutional review board approved this study, and written informed consent was obtained from 21 patients (13 men and eight women; mean age, 72 years) prior to enrollment. Each patient underwent chemical exchange saturation transfer MR imaging by using respiratory-synchronized half-Fourier fast spin-echo imaging after a series of magnetization transfer pulses. Next, a magnetization transfer ratio asymmetry at 3.5 ppm map was computationally generated. Pathology examinations resulted in a diagnosis of 13 malignant and eight benign thoracic lesions. The malignant lesions were further diagnosed as being nine lung cancers, comprising six adenocarcinomas, three squamous cell carcinomas, and four other thoracic malignancies. The Student t test was used to evaluate the capability of magnetization transfer ratio asymmetry (at 3.5 ppm), as assessed by means of region of interest measurements, for differentiating benign and malignant lesions, lung cancers and other thoracic lesions, and adenocarcinomas and squamous cell carcinomas. RESULTS Magnetization transfer ratio asymmetry (at 3.5 ppm) was significantly higher for malignant tumors (mean ± standard deviation, 3.56% ± 3.01) than for benign lesions (0.33% ± 0.38, P = .008). It was also significantly higher for other thoracic malignancies (6.71% ± 3.46) than for lung cancer (2.16% ± 1.41, P = .005) and for adenocarcinoma (2.88% ± 1.13) than for squamous cell carcinoma (0.71% ± 0.17, P = .02). CONCLUSION Amide proton transfer-weighted chemical exchange saturation transfer MR imaging allows characterization of thoracic lesions.

Standard-, Reduced-, and No-Dose Thin-Section Radiologic Examinations: Comparison of Capability for Nodule Detection and Nodule Type Assessment in Patients Suspected of Having Pulmonary Nodules

Purpose To compare the capability of pulmonary thin-section magnetic resonance (MR) imaging with ultrashort echo time (UTE) with that of standard- and reduced-dose thin-section computed tomography (CT) in nodule detection and evaluation of nodule type. Materials and Methods The institutional review board approved this study, and written informed consent was obtained from each patient. Standard- and reduced-dose chest CT (60 and 250 mA) and MR imaging with UTE were used to examine 52 patients; 29 were men (mean age, 66.4 years ± 7.3 [standard deviation]; age range, 48-79 years) and 23 were women (mean age, 64.8 years ± 10.1; age range, 42-83 years). Probability of nodule presence was assessed for all methods with a five-point visual scoring system. All nodules were then classified as missed, ground-glass, part-solid, or solid nodules. To compare nodule detection capability of the three methods, consensus for performances was rated by using jackknife free-response receiver operating characteristic analysis, and κ analysis was used to compare intermethod agreement for nodule type classification. Results There was no significant difference (F = 0.70, P = .59) in figure of merit between methods (standard-dose CT, 0.86; reduced-dose CT, 0.84; MR imaging with UTE, 0.86). There was no significant difference in sensitivity between methods (standard-dose CT vs reduced-dose CT, P = .50; standard-dose CT vs MR imaging with UTE, P = .50; reduced-dose CT vs MR imaging with UTE, P >.99). Intermethod agreement was excellent (standard-dose CT vs reduced-dose CT, κ = 0.98, P < .001; standard-dose CT vs MR imaging with UTE, κ = 0.98, P < .001; reduced-dose CT vs MR imaging with UTE, κ = 0.99, P < .001). Conclusion Pulmonary thin-section MR imaging with UTE was useful in nodule detection and evaluation of nodule type, and it is considered at least as efficacious as standard- or reduced-dose thin-section CT.

Comparison of Interobserver Agreement and Diagnostic Accuracy for IASLC/ITMIG Thymic Epithelial Tumor Staging Among Co-registered FDG-PET/MRI, Whole-body MRI, Integrated FDG-PET/CT, and Conventional Imaging Examination with and without Contrast Media Administrations

RATIONALE AND OBJECTIVES The purpose of this study was to compare the interobserver agreements and diagnostic accuracies for IASLC/ITMIG (International Association for the Study of Lung Cancer/International Thymic Malignancies Interest Group) thymic epithelial tumor staging of co-registered fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (FDG-PET/MRI), MRI, integrated fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT), and conventional imaging examination. MATERIALS AND METHODS Prospective whole-body MRI including diffusion-weighted imaging, integrated PET/CTs, conventional imaging examinations, pathological examinations, and surgical reports, as well as follow-up examinations, were performed for 64 consecutive patients with thymic epithelial tumor. All FDG-PET/MRIs were co-registered PET data with MRI. TNM staging was evaluated by two radiologists on the basis of the IASLC/ITMIG thymic epithelial tumor staging system. Kappa statistics were determined for evaluations of agreements of all factors between each of the methods and final diagnosis. Finally, the diagnostic accuracy of each factor and of determination of the clinical stage was statistically compared to each other using McNemar test. RESULTS Agreements for all factors between each method and final diagnosis were assessed as fair, moderate, substantial, or almost perfect (0.28 ≤ kappa value ≤ 0.80; P < .0001). Diagnostic accuracy for N factor of PET/MRI (93.8% [60/64]) and MRI (93.8% [60/64]) was significantly higher than that of conventional imaging examination (81.3% [52/64] vs PET/MRI and MRI; P = .008). In addition, diagnostic accuracy for staging of PET/MRI (84.4% [54/64]) and MRI (84.4 [54/64]) was significantly higher than that of conventional imaging examination (71.9% [46/64] vs PET/MRI and MRI; P = .008). CONCLUSIONS Whole-body PET/MRI, MRI, and PET/CT have better interobserver agreements and accuracies than conventional imaging examination for the new IASLC/ITMIG thymic epithelial tumor staging.