Takashi Okafuji

Parotid gland tumors: can addition of diffusion-weighted MR imaging to dynamic contrast-enhanced MR imaging improve diagnostic accuracy in characterization?

PURPOSE To determine the value of adding diffusion-weighted (DW) magnetic resonance (MR) imaging to dynamic contrast material-enhanced MR imaging when distinguishing between benign and malignant parotid tumors. MATERIALS AND METHODS This retrospective study was approved by the institutional review board, and the informed consent requirement was waived. The authors analyzed MR images of 50 lesions (36 benign, 14 malignant) in 47 patients. DW MR imaging and dynamic contrast-enhanced MR imaging were performed in all patients. Time-intensity curve (TIC) patterns were categorized as follows: type A, time to peak was more than 120 seconds; type B, time to peak was 120 seconds or less with high washout ratio (> or = 30%); type C, time to peak was 120 seconds or less with low washout ratio (< 30%); and type D, flat. The apparent diffusion coefficient (ADC) values were measured on DW MR images. Sensitivity, specificity, accuracy, and positive and negative predictive values were calculated for type A, B, and D tumors regarded as benign and for type C tumors regarded as malignant. On the basis of DW MR imaging results, ADC threshold values between pleomorphic adenomas and carcinomas and between Warthin tumors and carcinomas were selected. Diagnostic accuracy was compared before and after modification diagnosis referring to the ADC value obtained with the McNemar test. P < .05 was considered to indicate a significant difference. RESULTS ADC threshold values were 1.4 x 10(-3) mm(2)/sec between pleomorphic adenomas and carcinomas and 1.0 x 10(-3) mm(2)/sec between Warthin tumors and carcinomas. Accuracy (82% vs 94%) and positive predictive value (67% vs 92%) significantly improved with the addition of ADC values in the evaluation of patients with type B or C tumors. CONCLUSION A persistent or flat TIC pattern on dynamic contrast-enhanced MR images indicates benign disease, but there is added value from including the ADC value in the evaluation of tumors that show a plateau or washout TIC pattern.

Enhanced mass on contrast-enhanced breast MR imaging: Lesion characterization using combination of dynamic contrast-enhanced and diffusion-weighted MR images

To evaluate the diagnostic accuracy of a combination of dynamic contrast‐enhanced MR imaging (DCE‐MRI) and diffusion‐weighted MR imaging (DWI) in characterization of enhanced mass on breast MR imaging and to find the strongest discriminators between carcinoma and benignancy.

Non-mass-like enhancement on contrast-enhanced breast MR imaging: Lesion characterization using combination of dynamic contrast-enhanced and diffusion-weighted MR images

PURPOSE To evaluate the diagnostic accuracy of a combination of dynamic contrast-enhanced MR imaging (DCE-MRI) and diffusion-weighted MR imaging (DWI) in characterization of lesions showing non-mass-like enhancement on breast MR imaging and to find the strongest discriminators between carcinoma and benignancy. MATERIALS AND METHODS We analyzed consecutive MR images in 45 lesions showing non-mass like enhancement in 41 patients. We analyzed lesion size, distribution, internal enhancement, kinetic curve pattern, and apparent diffusion coefficient (ADC) values. We applied univariate and multivariate analyses to find the strongest indicators for malignancy. In a validation study, 22 non-mass-like enhancement lesions in 21 patients were examined. We calculated diagnostic accuracy when we presume category 4b, 4c, and 5 lesions as malignant or high to moderate suspicion for malignancy, and category 4a and 3 as low suspicion for malignancy or benign. RESULTS Segmental distribution (P=0.018), clumped internal enhancement (P=0.005), and ADC less than 1.3 x 10(-3) mm(2)/s (P=0.047) were the strongest MR indicators of malignancy. In a validation study, sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 87% (13/15), 86% (6/7), 93% (13/14), 75% (6/8) and 86% (19/22), respectively. CONCLUSION The combination of DCE-MRI and DWI showed high diagnostic accuracy in characterization of non-mass-like enhancement lesions on breast MR images.

Pulmonary Complications after Hepatic Artery Chemoembolization or Infusion via the Inferior Phrenic Artery for Primary Liver Cancer

PURPOSE The purpose of this study was to determine the frequency, patterns of disease, and risk factors for development of pulmonary complications after liver chemoembolization via the inferior phrenic artery (IPA). MATERIALS AND METHODS Forty-four selective transcatheter hepatic chemoembolization (THCE) procedures via the IPA were performed in patients with primary liver cancers with use of a mixture of anticancer agents and iodized oil (Lipiodol) with or without transcatheter arterial embolization. The grades of pulmonary complications were assessed on triphasic helical computed tomographic (CT) images after THCE and were correlated with angiographic findings of the IPA, infused dosages of Adriamycin and Lipiodol, and hepatic venous tumor thrombus on triphasic CT images before THCE. RESULTS THCE via the IPA frequently resulted in lung CT changes: Lipiodol accumulation in the lung field (52%), consolidation (68%), and pleural effusion (41%). Among 44 patients, two (5%) developed respiratory symptoms. An excellent correlation was shown between Lipiodol accumulation and the presence of angiographic abnormalities of the IPA (P <.005). A significant correlation was also shown between the grades of pulmonary complications and the numbers of angiographic abnormalities (P <.01). The grades of pulmonary complications increased according to the infused dosage of Adriamycin and Lipiodol (P <.05). CONCLUSIONS Angiographic abnormalities such as arteriovenous shunts, dilated anastomotic branches, and dense pleural staining are important risk factors for pulmonary complications of THCE via the IPA. Embolization for shunts may be required to prevent such complications, especially in cases with shunts to pulmonary vessels or hepatic veins.

Detection of masses and microcalcifications of breast cancer on digital mammograms: comparison among hard-copy film, 3-megapixel liquid crystal display (LCD) monitors and 5-megapixel LCD monitors: an observer performance study

The purpose of the study was to compare observer performance in the detection of masses and microcalcifications of breast cancer among hard-copy reading and soft-copy readings using 3-megapixel (3M) and 5-megapixel (5M) liquid crystal display (LCD) monitors. For the microcalcification detection test, we prepared 100 mammograms: 40 surgically verified cancer cases and 60 normal cases. For the mass detection test, we prepared 100 mammograms: 50 cancer cases and 50 normal cases. After six readers assessed both microcalcifications and masses set for each modality, receiver operating characteristic (ROC) analysis was performed. The average Azs for mass detection using a hard copy and 3M and 5M LCD monitors were 0.923, 0.927 and 0.920, respectively; there were no significant differences. The average Az for microcalcification detection using hard copy, 3M and 5M LCD monitors was 0.977, 0.954 and 0.972, respectively. There were no significant differences, but the P-values between the hard copy and 3M LCD monitor and that between the 3M and 5M LCD monitor were 0.08 and 0.09, respectively. In conclusion, the observer performances for detecting masses of breast cancers were comparable among the hard copy and two LCD monitors; however, soft-copy reading with a 3M LCD monitor showed slightly lower observer performance for detecting microcalcifications of breast cancers than hard-copy or 5M LCD monitor reading.

Alteration of proton diffusivity associated with passive muscle extension and contraction

To determine whether passive muscle extension and contraction affect the proton diffusivity of the muscle.

Computer-Aided Nodule Detection on Digital Chest Radiography: Validation Test on Consecutive T1 Cases of Resectable Lung Cancer

PurposeTo evaluate the usefulness of a commercially available computer-assisted diagnosis (CAD) system on operable T1 cases of lung cancer by use of digital chest radiography equipment.Materials and MethodsFifty consecutive patients underwent surgery for primary lung cancer, and 50 normal cases were selected. All cancer cases were histopathologically confirmed T1 cases. All normal individuals were selected on the basis of chest computed tomography (CT) confirmation and were matched with cancer cases in terms of age and gender distributions. All chest radiographs were obtained with one computed radiography or two flat-panel detector systems. Eight radiologists (four chest radiologists and four residents) participated in observer tests and interpreted soft copy images by using an exclusive display system without and with CAD output. When radiologists diagnosed cases as positives, the locations of lesions were recorded on hard copies. The observers’ performance was evaluated by receiver operating characteristic analysis.ResultsThe overall detectability of lung cancer cases with CAD system was 74% (37/50), and the false-positive rate was 2.28 (114/50) false positives per case for normal cases. The mean Az value increased significantly from 0.896 without CAD output to 0.923 with CAD output (P = 0.018). The main cause of the improvement in performance is attributable to changes from false negatives without CAD to true positives with CAD (19/31, 61%). Moreover, improvement in the location of the tumor was observed in 1.5 cases, on average, for radiology residents.ConclusionThis CAD system for digital chest radiographs is useful in assisting radiologists in the detection of early resectable lung cancer.

Pulmonary lesions associated with visceral larva migrans due to Ascaris suum or Toxocara canis : Imaging of six cases

OBJECTIVE The objective of our study was to evaluate chest radiographic and CT findings of patients with pulmonary lesions associated with visceral larva migrans due to Ascaris suum or Toxocara canis. CT investigation was focused on the location, size, contour, and internal features of the lesions; migration of lesions; mediastinal lymphadenopathy; and pleural effusion. CONCLUSION Pulmonary visceral larva migrans appears on CT as multifocal subpleural nodules with halo or ground-glass opacities and ill-defined margins.

CT and MR findings of brain aspergillosis.

CT and MR findings of a case of brain aspergillosis with histopathologic correlation are reported. On both CT and MR images, there were multiple lesions in the corticomedullary junction (CMJ) that appeared to disrupt the cortical sulci and that were not enhanced by intravenous contrast material. In most of these lesions, there were centrally located structures that were enhanced by intravenous contrast material and that appeared to be continuous from markedly enhanced adjacent dilated cortical vessels. Histopathologic examination of the autopsy specimen showed multiple hemorrhagic infarcts in the CMJ with remaining dilated cortical vessels that had been thrombosed by aspergillus hyphae.

Computed tomographic and magnetic resonance features of inflammatory myofibroblastic tumor of the lung in children

We report two cases of inflammatory myofibroblastic tumor (IMT) of the lung in a 4-year-old boy and a 7-year-old girl. We performed dynamic contrastenhancement computed tomography in both of our cases and dynamic contrast enhancement magnetic resonance imaging (MRI) in one case. These dynamic studies showed a demarcated mass with delayed enhancement in both cases. A T1-weighted MR image shows a mass with homogeneous low signal intensity, and a T2- weighted image shows a mass with slightly high signal intensity. A post-contrast-enhanced T1-weighted image demonstrates homogeneous enhancement. We speculate that the delayed enhancement could be attributed to the abundant fibrous tissue, which was the main structural material of the tumor. This same finding has been described in previous reports of IMT in other organs.