Free-breathing Diffusion-weighted Imaging Research Articles

Detection of Hepatic Lesion: Comparison of Free-Breathing and Respiratory-Triggered Diffusion-Weighted MR imaging on 1.5-T MR system

Purpose : To compare free-breathing and respiratory-triggered diffusion-weighted imaging on 1.5-T MR system in the detection of hepatic lesions. Materials and Methods: This single-institution study was approved by our institutional review board. Forty-seven patients (mean 57.9 year; M:F = 25:22) underwent hepatic MR imaging on 1.5-T MR system using both free-breathing and respiratory-triggered diffusion-weighted imaging (DWI) at a single examination. Two radiologists retrospectively reviewed respiratory-triggered and free-breathing sets (B50, B400, B800 diffusion weighted images and ADC map) in random order with a time interval of 2 weeks. Liver SNR and lesion-to-liver CNR of DWI were calculated measuring ROI. Results : Total of 62 lesions (53 benign, 9 malignant) that included 32 cysts, 13 hemangiomas, 7 hepatocellular carcinomas (HCCs), 5 eosinophilic infiltration, 2 metastases, 1 eosinophilic abscess, focal nodular hyperplasia, and pseudolipoma of Glisson's capsule were reviewed by two reviewers. Though not reaching statistical significance, the overall lesion sensitivities were increased in respiratory-triggered DWI [reviewer1: reviewer2, 47/62(75.81%):45/62(72.58%)] than free-breathing DWI [44/62(70.97%):41/62(66.13%)]. Especially for smaller than 1 cm hepatic lesions, sensitivity of respiratory-triggered DWI [24/30(80%):21/30(70%)] was superior to free-breathing DWI [17/30(56.7%):15/30(50%)]. The diagnostic accuracy measuring the area under the ROC curve (Az value) of free-breathing and respiratory-triggered DWI was not statistically different. Liver SNR and lesion-to-liver CNR of respiratory-triggered DWI (, ) were higher than free-breathing DWI (, ) (p value

Diagnostic Performance of Diffusion-Weighted MRI in the Detection of Nonpalpable Undescended Testes: Comparison With Conventional MRI and Surgical Findings

The aim of this feasibility study was to evaluate the role of diffusion-weighted MRI in the evaluation of nonpalpable undescended testes. Thirty-six boys with undescended testes underwent preoperative abdominal and pelvic MRI to identify the location of the testes. MRI included free-breathing diffusion-weighted imaging (DWI) with b values of 50, 400, and 800 s/mm(2), a T1-weighted turbo spin-echo sequence, and a T2-weighted fat-suppressed turbo spin-echo sequence. After laparoscopic examinations, two observers independently reviewed the preoperative images. The DW images alone were reviewed first, followed by the conventional MR images alone and the conventional MR and the DW images together. The laparoscopic and MRI findings were compared. Sensitivity, specificity, and accuracy in the identification of nonpalpable undescended testes were calculated for DWI, conventional MRI, and the combination of DWI and conventional MRI. The combination of DWI and conventional MRI was the most sensitive and most accurate technique. Observer 1 found 31 undescended testes, and observer 2, 30 testes with this technique. Sensitivity was 0.91 and 0.88 for observers 1 and 2, and accuracy was 0.92 and 0.86. With DWI alone, observer 1 located 30 testes, and observer 2, 28 testes (sensitivity, 0.88 and 0.82; accuracy, 0.86 and 0.81). Using conventional MRI alone, both observers located 29 testes (sensitivity, 0.85; accuracy, 0.86 and 0.84). The accuracy of locating testes was superior with the combination of DWI and conventional MRI for both observers (accuracy, 0.92 and 0.86). An intraabdominal atrophic testis managed by laparoscopic orchiectomy was found by neither observer with DWI or with conventional MRI. Use of DWI with a high b value yields information that complements conventional MRI findings, improving identification and location of nonpalpable undescended testes. We recommend the use of conventional MRI in addition to DWI to increase the preoperative sensitivity and accuracy of identifying and locating nonpalpable testes.

Differentiation between cavernous hemangiomas and untreated malignant neoplasms of the liver with free-breathing diffusion-weighted MR imaging: Comparison with T2-weighted fast spin-echo MR imaging

To test interobserver variability of ADC measurements and compare the diagnostic performances of free-breathing diffusion-weighted (FBDW) with that of T2-weighted FSE (T2WFSE) MR imaging for differentiating between cavernous hemangiomas and untreated malignant hepatic neoplasms. Thirty-five patients with cavernous hemangiomas and 35 with untreated hepatic malignant neoplasms had FBDW and T2WFSE MR imaging. Hepatic lesions were characterized with ADC measurement and visual evaluation. Interobserver agreement for ADC measurement was calculated. Association between ADC value and lesion type was assessed using univariate analysis. Sensitivity, specificity and accuracy of ADC values and visual evaluation of MR images for the diagnosis of untreated malignant hepatic neoplasm were compared. ADC measurements showed excellent interobserver correlation (intraclass correlation coefficient=0.980). Malignant neoplasms had lower ADC values than hemangiomas for the two observers (1.11×10(-3) mm2/s±.21×10(-3) vs. 1.77×10(-3) mm2/s±.29×10(-3) for observer 1 and 1.11×10(-3) mm2/s±.19×10(-3) vs. 1.79×10(-3) mm2/s±.32×10(-3) for observer 2) and univariate analysis found significant correlations between lesion type and ADC values. Depending on ADC threshold value, accuracy for the diagnosis of malignant neoplasm varied from 82.9% to 94.3%. Using visual evaluation, FBDW showed better specificity and accuracy than T2WFSE MR images for the diagnosis of malignant neoplasm (97.1% vs. 77.1% and 94.3% vs. 62.9%, respectively). FBDW imaging provides reproducible quantitative information and surpasses the value of T2WFSE MR imaging for differentiating between cavernous hemangiomas and untreated malignant hepatic neoplasms.

Diffusion Weighted Imaging of Pediatric and Adolescent Malignancies with Regard to Detection and Delineation: Initial Experience 2

To assess the value of diffusion weighted imaging (DWI) magnetic resonance imaging (MRI) in pediatric and adolescent tumor patients with focus on detection and delineation of malignant tumors of the central nervous system, chest, abdomen, and musculoskeletal system. Twenty-nine pediatric and adolescent patients (17 males, 12 females, age, 2 months-20 years, mean age: 8.9 years) with clinically suspected malignant tumors were examined with use of a 1.5-T MR scanner with open bore design without sedation or general anesthesia. DWI images were acquired with a single-shot echo planar imaging (EPI) sequence in free breathing with b-values of 0, 500, and 1000 mm/s(2). Images were assessed by two readers in consensus. Artifacts in DWI were graded as not relevant, acceptable, or nondiagnostic. DWI/apparent diffusion coefficient maps were correlated with T1-weighted post-contrast images, and the detectability and correct delineation of the tumors were graded using a three grade scale. Free-breathing DWI was successfully performed in all patients. In 27 patients, no relevant artifacts were observed; acceptable artifacts were seen in two patients. In all patients, malignancies were detected both on DWI and T1-weighted gadolinium images. Detection and delineation of tumors were possible in all cases with both sequences; T1-weighted gadolinium imaging was superior to DWI in only three patients. Additionally, small diffusion restricted lymph nodes were detected in three patients. DWI is reliable for the accurate detection and delineation of malignant pediatric and adolescent tumors.