Significance of combined use of MRI and perfusion SPECT for evaluation of multiple system atrophy, cerebellar type.

BACKGROUND: Multiple system atrophy, cerebellar type (MSA-C) sometimes shows asymmetrical findings on magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT). PURPOSE: To assess the frequency and clinical significance of asymmetrical MRI and (99m)Tc-ethyl cysteinate dimer perfusion (ECD) SPECT findings of the cerebellum, middle cerebellar peduncle (MCP), and pons in MSA-C patients. MATERIAL AND METHODS: We retrospectively reviewed 28 patients with MSA-C who underwent MRI and (99m)Tc-ECD SPECT and evaluated laterality of atrophy and signal changes on MRI, and laterality of perfusion on (99m)Tc-ECD SPECT transversely and longitudinally. RESULTS: Laterality was identified for 64%, 61%, and 21% of atrophy in the cerebellum, MCP, and pons, respectively, on MRI and for 71% of atrophy in the cerebellum on perfusion SPECT. Concerning comparisons between the latest MRI and SPECT findings, laterality of cerebellar/MCP atrophy on MRI and decreased cerebellar perfusion on SPECT was matched in 57%, mismatched in 11%, and absent in 25% of patients. On past images, MRI and SPECT showed matched laterality in 33%, mismatched laterality in 27%, no laterality in 13%, and SPECT precedent laterality in 27% of patients. Including the latest and past images, asymmetrical changes were observed in 75% of patients. We could not identify any correlation between laterality of image findings and cerebellar symptoms in most patients. CONCLUSION: Asymmetrical changes on MRI and perfusion SPECT are common in MSA-C patients. Perfusion SPECT is useful for diagnosing MSA-C in the early stages from a functional perspective.

Significance of apparent diffusion coefficient measurement for the differential diagnosis of multiple system atrophy, progressive supranuclear palsy, and Parkinson's disease: evaluation by 3.0-T MR imaging.

INTRODUCTION: The clinical differentiation of Parkinson's disease (PD) from multiple system atrophy (MSA) and progressive supranuclear palsy (PSP) may be challenging, especially in their early stages. The aim of this study was to evaluate the utility of apparent diffusion coefficient (ADC) measurement to distinguish among these degenerative disorders. METHODS: Twenty-five MSA, 20 PSP, and 17 PD patients and 18 healthy controls were retrospectively studied. Axial diffusion-weighted and T2-weighted images were obtained using a 3-T MR system. Regions of interest (ROIs) were precisely placed in the midbrain, pons, putamen, globus pallidus, caudate nucleus, thalamus, superior cerebellar peduncle, middle cerebellar peduncle, cerebellar white matter, and cerebellar dentate nucleus, and the regional ADC (rADC) value was calculated in each ROI. RESULTS: In MSA, rADC values in the pons, middle cerebellar peduncle, cerebellar white matter, and cerebellar dentate nucleus were significantly higher than in PSP, PD, and controls. Furthermore, rADC values in the posterior putamen were significantly higher in MSA than in PSP and controls. In PSP, rADC values were significantly higher in the globus pallidus and midbrain than in MSA, PD, and controls. Furthermore, rADC values in the caudate nucleus and superior cerebellar peduncle were significantly higher in PSP than in MSA and controls. In PD, there were no significant differences in the rADC values compared to in MSA, PSP, and controls in all regions. CONCLUSION: Evaluation of rADC values in characteristic lesions in MSA, PSP, and PD by placing ROIs using 3-T systems can provide useful additional information for differentiating these disorders.

Comparison of increased venous contrast in ischemic stroke using phase-sensitive MR imaging with perfusion changes on flow-sensitive alternating inversion recovery at 3 Tesla.

BACKGROUND: Increased venous contrast in ischemic stroke using susceptibility-weighted imaging has been widely reported, although few reports have compared increased venous contrast areas with perfusion change areas. PURPOSE: To compare venous contrast on phase-sensitive MR images (PSI) with perfusion change on flow-sensitive alternating inversion recovery (FAIR) images, and to discuss the clinical use of PSI in ischemic stroke. MATERIAL AND METHODS: Thirty patients with clinically suspected acute infarction of the middle cerebral artery (MCA) territory within 7 days of onset were evaluated. Phase-sensitive imaging (PSI), flow-sensitive alternating inversion recovery (FAIR), diffusion-weighted imaging (DWI) and magnetic resonance angiography (MRA) were obtained using 3 Tesla scanner. Two neuroradiologists independently reviewed the MR images, as well as the PSI, DWI, and FAIR images. They were blinded to the clinical data and to each other's findings. The abnormal area of each image was ultimately identified after both neuroradiologists reached consensus. We analyzed areas of increased venous contrast on PSI, perfusion changes on FAIR images and signal changes on DWI for each case. RESULTS: Venous contrast increased on PSI and hypoperfusion was evident on FAIR images from 22 of the 30 patients (73%). The distribution of the increased venous contrast was the same as that of the hypoperfused areas on FAIR images in 16 of these 22. The extent of these lesions was larger than that of lesions visualized by on DWI in 18 of the 22 patients. Hypointense signals reflecting hemorrhage and no increased venous contrast on PSI and hyperperfusion on FAIR images were found in six of the remaining eight patients (20%). Findings on PSI were normal and hypoperfusion areas were absent on FAIR images of two patients (7%). CONCLUSION: Increased venous contrast on PSI might serve as an index of misery perfusion and provide useful information.

Diffusion-weighted imaging of uterine endometrial stromal sarcoma: a report of 2 cases.

We demonstrated 2 cases of uterine endometrial stromal sarcoma with emphasis on diffusion-weighted imaging. The tumors showed high signal intensity, and their tumor venous thrombi were clearly depicted on diffusion-weighted imaging. Diffusion-weighted imaging is a useful method not only for diagnosis of endometrial stromal sarcoma but also for preoperative planning.

Putaminal lesion in multiple system atrophy: postmortem MR-pathological correlations.

INTRODUCTION: Posterior putaminal atrophy, putaminal T2-hyper and/or hyposignal changes have been observed in patients with multiple system atrophy (MSA) with parkinsonism. METHODS: Postmortem T2-weighted images were compared with histological findings in seven autopsy-proven cases of putaminal lesions of MSA. All cases were evaluated on 1.5T magnetic resonance imaging (MRI) scanners and three cases were evaluated on 3T scanners. RESULTS: There were three types of putaminal changes: Type 1, mild putaminal atrophy and isointensity; Type 2, putaminal atrophy and diffuse hyperintensity with a hyperintense putaminal rim (HPR); Type 3, putaminal atrophy and iso-or-hypointensity with HPR. The signal intensities of the putamen in Types 1 and 3 were more hypointense on 3T images than on 1.5T images. In Type 1, mild putaminal atrophy showed mild neuronal loss and gliosis and diffuse ferritin deposition. In Types 2 and 3, the areas of putaminal atrophy, severe in the posterior region, showed severe neuronal loss and gliosis, many pigments that were positive for ferritin and Fe (3+) and diffuse ferritin deposition. Although, tissue rarefaction was more severe in Type 2 than in Type 3, pigment deposition was more severe in Type 3. The HPR showed a severe loss of myelin and axons with tissue rarefaction of the external capsule or putaminal rim in Types 2 and 3. CONCLUSION: Posterior putaminal atrophy reflects neuronal loss and gliosis. While putaminal iso-or -hypointensity reflects diffuse ferritin and Fe(3+) deposition, hyperintensity reflects tissue rarefaction. The HPR reflects degeneration of the putaminal lateral margin and/or external capsule. These findings reflect characteristic histological findings of MSA with parkinsonism.

Radiation-induced microbleeds after cranial irradiation: evaluation by phase-sensitive magnetic resonance imaging with 3.0 tesla.

BACKGROUND: Although there are many reports regarding radiation-induced microbleeds, its frequency, relation to dose and latency after radiation are not fully elucidated. The purpose of this study was to evaluate the frequency, latency, patient factors and dose relation of radiation-induced microbleeds after cranial irradiation using phase-sensitive magnetic resonance imaging (PSI) at 3.0 T. METHODS: Retrospective evaluation of 34 patients (age range, 13-78 years; mean, 49 years; follow-up period, 3-169 months; mean 29 months) who had undergone cranial irradiation using magnetic resonance (MR) imaging including PSI was performed. Twenty-three patients received high-dose irradiation (44-60 Gy), and 11 patients received 24-30 Gy whole brain irradiation. When microbleeds were detected on MR imaging in these high-dose irradiation patients, dose distribution maps were reproduced by reviewing the clinical records. Then the irradiated areas were divided into 6 radiation-dose classes: regions > 55 Gy, 45-55 Gy, 35-45 Gy, 25-35 Gy, 15-25 Gy and 5-15 Gy. The frequency of microbleeds in each radiation-dose class was analyzed. RESULTS: Microbleeds were detected in 7 (21%) of 34 patients on T2-weighted imaging, whereas they were detected in 16 (47%) of the 34 patients on PSIs. The frequency of microbleeds was higher than previously reported. The latency of radiation-induced microbleeds after radiation was 3 months to 9 years (mean, 33 months). In high-dose irradiation patients, the frequency of microbleeds significantly was associated with radiation dose. There were no foci that were observed in regions that had received < 25 Gy. CONCLUSION: Radiation-induced microbleeds occurred more frequently in the present study than has been previously reported. PSI can be used to detect these vascular changes earlier than other conventional MR imaging techniques.

Evaluation of a noise reduction procedure for chest radiography.

BACKGROUND: The aim of this study was to evaluate the usefulness of noise reduction procedure (NRP), a function in the new image processing for chest radiography. METHODS: A CXDI-50G Portable Digital Radiography System (Canon) was used for X-ray detection. Image noise was analyzed with a noise power spectrum (NPS) and a burger phantom was used for evaluation of density resolution. The usefulness of NRP was evaluated by chest phantom images and clinical chest radiography. We employed the Bureau of Radiological Health Method for scoring chest images while carrying out our observations. RESULTS: NPS through the use of NRP was improved compared with conventional image processing (CIP). The results in image quality showed high-density resolution through the use of NRP, so that chest radiography examination can be performed with a low dose of radiation. Scores were significantly higher than for CIP. CONCLUSION: In this study, use of NRP led to a high evaluation in these so we are able to confirm the usefulness of NRP for clinical chest radiography.

Primary fourth ventricular meningioma: a case report of an adult male.

Primary fourth ventricular meningiomas are extremely rare and often misdiagnosed as other tumors. They have no characteristic imaging appearance on computed tomography and magnetic resonance imaging. Therefore, differentiating the lesion from common lesions in the fourth ventricle can be diagnostically challenging. In this report, we present a 25-year-old man with fourth ventricular meningioma and refer to the usefulness of diffusion-weighted imaging and apparent diffusion coefficient measurements for the differential diagnosis of fourth ventricular tumors.

Three-dimensional gradient echo versus spin echo sequence in contrast-enhanced imaging of the pituitary gland at 3T.

INTRODUCTION: To clarify whether a three-dimensional-gradient echo (3D-GRE) or spin echo (SE) sequence is more useful for evaluating sellar lesions on contrast-enhanced T1-weighted MR imaging at 3.0Tesla (T). METHODS: We retrospectively assessed contrast-enhanced T1-weighted images using 3D-GRE and SE sequences at 3.0T obtained from 33 consecutive patients with clinically suspected sellar lesions. Two experienced neuroradiologists evaluated the images qualitatively in terms of the following criteria: boundary edge of the cavernous sinus and pituitary gland, border of sellar lesions, delineation of the optic nerve and cranial nerves within the cavernous sinus, susceptibility and flow artifacts, and overall image quality. RESULTS: At 3.0T, 3D-GRE provided significantly better images than the SE sequence in terms of the border of sellar lesions, delineation of cranial nerves, and overall image quality; there was no significant difference regarding the boundary edge of the cavernous sinus and pituitary gland. In addition, the 3D-GRE sequence showed fewer pulsation artifacts but more susceptibility artifacts. CONCLUSION: Our results indicate that 3D-GRE is the more suitable sequence for evaluating sellar lesions on contrast-enhanced T1-weighted imaging at 3.0T.

Diffusion-weighted imaging findings of adnexal torsion: initial results.

Our purpose is to clarify the diffusion-weighted (DW) imaging findings of adnexal torsion. We retrospectively analyzed the DW imaging findings in 11 consecutive patients with surgical confirmation of adnexal torsion. We assessed signal intensity of the adnexal mass and fallopian tube thickening, and the location of abnormal signal intensity within the adnexal mass. On DW imaging, thickening of the fallopian tube was apparent as abnormal signal intensity in 8 of 11 patients. Abnormal signal intensity was inhomogeneous in 7 of 8 patients. Abnormal signal intensity on DW imaging was observed in 10 of 11 adnexal masses, and in the walls of 7 out of 8 adnexal cystic lesions. In adnexal torsion, DW imaging showed abnormal signal intensity in the thickened fallopian tube and in the wall of cystic ovarian lesions. These findings would be feasible to diagnose adnexal torsion.

Usefulness of administration of SPIO prior to RF ablation for evaluation of the therapeutic effect: an experimental study using miniature pigs.

OBJECTIVES: To evaluate the usefulness of administration of superparamagnetic iron oxide (SPIO) and magnetic resonance (MR) imaging for assessing the efficacy of radiofrequency (RF) liver ablation. MATERIAL AND METHODS: Using a protocol approved by the animal research committee of our university, nine RF liver ablations were performed in three miniature pigs. Six ablations were performed after administration of SPIO in two pigs (group A). Three ablations were performed in the other pig without administration of SPIO (group B). All pigs were sacrificed 4 days after the procedure. Harvested livers were scanned with a 1.5T MR system before and after fixation with 10% buffered formalin, and MR images were precisely compared with histological specimens. RESULTS: There were no histological differences between the two groups. All ablated liver lesions showed coagulation necrosis at the external layer. There were no viable cells inside the coagulation necrosis. All ablated lesions had a hypointense rim on fast low angle shot (FLASH) images. The rims of group A were thicker than those of group B. The rims of group B corresponded histologically to congestion and hemorrhagic necrosis area. The rims of the group A corresponded to hemorrhagic necrosis and coagulation necrosis areas. In group A, the hypointense rim reflected necrotic Kupffer cells that took up SPIO before RF liver ablation. CONCLUSION: Administration of SPIO made it possible to precisely evaluate ablated liver parenchyma by hypointense rim on FLASH images. This method is helpful for the evaluation of safety margin after RF ablation for liver tumors.

Diagnostic accuracy of diffusion-weighted imaging in differentiating benign from malignant ovarian lesions.

PURPOSE: To clarify the diagnostic accuracy of diffusion-weighted imaging (DWI) in differentiating benign from malignant ovarian lesions. MATERIALS AND METHODS: We retrospectively analyzed magnetic resonance images of 123 ovarian lesions in 119 patients. We defined lesions with abnormal signal intensity as malignancy and assessed the location of abnormal intensity within the lesions on DWI. We also assessed the mean and lowest apparent diffusion coefficient (ADC) values of the solid portion for each ovarian lesion. RESULTS: The majority of malignant ovarian tumors and mature cystic teratomas, and almost half of the endometriomas, showed abnormal signal intensity on DWI, whereas most fibromas and other benign lesions did not. The main locations of abnormal signal intensity were solid portions in malignant ovarian tumors, cystic components suggestive of keratinoid substances and Rokitansky protuberance in mature cystic teratomas, and intracystic clots in endometriomas. On DW imaging, receiver-operating characteristic analysis yielded mean Az values of 0.703. There was no significant difference in mean and lowest ADC values between malignant and benign lesions. CONCLUSION: DWI of ovarian lesions and ADC values of the solid component are not useful for differentiating benign from malignant ovarian lesions. This knowledge is essential in avoiding misinterpretation in the diagnosis of ovarian lesions.

Detection of peritoneal dissemination in gynecological malignancy: evaluation by diffusion-weighted MR imaging.

The aim of this study is to evaluate the usefulness of diffusion-weighted (DW) magnetic resonance (MR) imaging in detecting peritoneal dissemination in cases of gynecological malignancy. We retrospectively analyzed MR images obtained from 26 consecutive patients with gynecological malignancy. Peritoneal dissemination was histologically diagnosed in 15 of the 26 patients after surgery. We obtained DW images and half-Fourier single-shot turbo-spin-echo images in the abdomen and pelvis, and then generated fusion images. Coronal maximum-intensity-projection images were reconstructed from the axial source images. Reader interpretations were compared with the laparotomy findings in the surgical records. Receiver-operating characteristic (ROC) curves were used to represent the presence of peritoneal dissemination. In addition, the sensitivity and specificity were calculated. DW imaging depicted the tumors in 14 of 15 patients with peritoneal dissemination as abnormal signal intensity. ROC analysis yielded Az values of 0.974 and 0.932 for the two reviewers. The mean sensitivity and specificity were 90 and 95.5%. DW imaging plays an important role in the diagnosis and therapeutic management of patients with gynecological malignancy.

Diagnostic accuracy of the apparent diffusion coefficient in differentiating benign from malignant uterine endometrial cavity lesions: initial results.

Our purpose is to evaluate the diagnostic accuracy of apparent diffusion coefficient (ADC) measurement in differentiating malignant from benign uterine endometrial cavity lesions. We retrospectively evaluated 25 uterine endometrial cavity lesions in 25 female patients: endometrial carcinoma (n = 11), carcinosarcoma (n = 2), submucosal leiomyoma (n = 8), and endometrial polyp (n = 4). Diffusion-weighted images were performed at 1.5 T with b factors of 0-1,000/mm(2). The region of interest was defined within the tumor on T2-weighted EPI image and then manually copied to an ADC map. Thereby, the ADC value was obtained. We compared ADC values between malignant and benign lesions using Student's t-test. The mean and standard deviation of ADC values (x10(-3) mm(2)/s) were as follows: endometrial carcinoma, 0.98+/-0.21; carcinosarcoma, 0.97+/-0.02; submucosal leiomyoma, 1.37+/-0.28; and endometrial polyp, 1.58+/-0.45. The ADC values differed significantly between malignant (0.98+/-0.19) and benign lesions (1.44+/-0.34) (P < 0.01). We defined malignant tumors as cases with an ADC value less than 1.15 x 10(-3) mm(2)/s for obtaining the highest accuracy. Sensitivity, specificity, and accuracy were 84.6%, 100%, and 92%, respectively. ADC measurement can provide useful information in differentiating malignant from benign uterine endometrial cavity lesions.