Measurement of variation in the human cerebral GABA level by in vivo MEGA-editing proton MR spectroscopy using a clinical 3 T instrument and its dependence on brain region and the female menstrual cycle.

The objectives of this study were to examine the reproducibility of the MEGA-editing J-difference technique and to determine the normal variation in the γ-aminobutyric acid (GABA) level depending on the cerebral region and its fluctuation according to the menstrual cycle as baseline data for clinical application. The participants consisted of 15 normal adult volunteers (eight men and seven women), and all measurements were repeated twice in all participants. The MEGA-editing pulses were incorporated into point-resolved spectroscopy on a 3 T instrument to obtain the J-difference editing spectra from a voxel located in the lentiform nuclei (LN), left frontal lobe (FL), and anterior cingulate cortex (AC). The GABA levels in the gray matter (GM) were compensated by the fraction ratios of the gray and white matters and cerebrospinal fluid in the measurement volume. The extent of the variation in GABA was almost the same as that observed in the major metabolites, and its reproducibility was also maintained (intraclass correlation coefficient > 0.7). GABA level was highest in LN and lowest in AC. A difference in the GABA level between the follicular and luteal phases of the menstrual cycle was found in both LN and FL, but not in AC. This technique showed the differences in the GABA levels in the GM and the region-specific decrease in the GABA levels during the women's luteal phase.

Measurements of multidetector CT surface dose distributions using a film dosimeter and chest phantom.

PURPOSE: This paper uses film dosimetry to investigate the relationship between multiple scan parameters of multidetector CT with automatic exposure control (AEC) and the surface dose distribution produced on a chest phantom. METHODS: The characteristics of the film used in the film dosimeter were evaluated with regard to linearity, relative film response, and directional dependence. Measurements with an ionization chamber dosimeter and a water phantom were used to evaluate the accuracy of the film dosimeter measurements and to validate the dose profile measurements while changing the tube current, detector dimensions and pitch. When using AEC, the surface dose distribution on the chest phantom was analyzed while changing the detector dimensions and pitch. RESULTS: The linearity, relative film response, and directional dependence of the film were established. The measurement difference between the film dosimeter and ionization chamber dosimeter was within +/- 5% and the dose profile measurement results were validated. It was found that the surface dose distribution changed helically in the direction of the body axis depending on the scan parameters and the phantom. CONCLUSIONS: Using a film dosimeter, the relationship between various multidetector CT scan parameters and the surface dose distribution on a chest phantom was investigated and clarified.

Incidence and clinical correlation of intracranial hemorrhages observed by 3-tesla gradient echo T(2)*-weighted images following intravenous thrombolysis with recombinant tissue plasminogen activator.

BACKGROUND: The purpose of this study was to determine the incidence and clinical correlation of intracranial hemorrhages (ICHs) detected by 3-tesla gradient echo T(2)*-weighted images after intravenous recombinant tissue plasminogen activator (rt-PA) administration. METHODS: We included 43 consecutive patients with anterior-circulation ischemia who underwent MRI studies before and after thrombolysis. Each hemorrhage was classified as a hemorrhagic infarction (HI) or parenchymal hemorrhage (PH) according to the European Cooperative Acute Stroke Study definition. The clinical outcome was defined as an improvement (> or =4-point reduction) or deterioration (> or =4-point increase) based on a comparison between the initial and the 30-day NIHSS scores. RESULTS: The incidence of ICHs was 58%, and the HI rate was 52%; both were higher than the rates reported in the literature. Most of the patients with HI improved clinically, and these patients had second MRAs that showed recanalization. None of the patients with PH demonstrated improvement. CONCLUSIONS: Three-tesla MRI may reveal a higher frequency of HI type hemorrhages than lower-field MRIs, and HI may be a predictor of good recovery by reflecting the presence of recanalization. The rate of PH in our study was low compared to other studies, probably due to the lower dosage of rt-PA.

Manifestations of the female reproductive organs on MR images: changes induced by various physiologic states.

Unlike other reproductive organs, the uterus and ovaries are known to undergo dynamic morphologic changes according to various physiologic states. It is vitally important for radiologists when diagnosing gynecologic disorders to understand how normal female reproductive organs appear on magnetic resonance (MR) images for a given physiologic state. The authors focused on the effects of the menstrual cycle, pregnancy, and aging on MR images of normal female reproductive organs. During menstruation, the zonal architecture of the uterine corpus may be indistinct and the ovarian stroma may shrink and have lower signal intensity on both T2- and diffusion-weighted (DW) images. During periovulation, the ovarian stroma may be reach its maximum size and have high signal intensity on both T2- and DW images. Functional cysts may often be seen in ovaries of reproductive age and usually spontaneously shrink, whereas surface-epithelial inclusion cysts may be commonly seen in postmenopausal ovaries. Pregnancy-related changes, such as decidual changes in ectopic endometrial tissue and hyperreactio luteinalis in ovaries, may mimic gynecologic tumors and must be correctly diagnosed to avoid unnecessary and excessive surgical intervention. The authors offer some clues that may be helpful for making the differential diagnosis when evaluating MR images of female reproductive organs. Radiologists should, as much as practicably possible, check the physiologic states of patients before interpreting MR images.

Diffusion-weighted magnetic resonance imaging of ovarian tumors: differentiation of benign and malignant solid components of ovarian masses.

OBJECTIVE: We evaluated the feasibility of diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) measurement in differentiating benign and malignant ovarian tumors. METHODS: Surgically proven 49 ovarian tumors (39 malignant/borderline malignant and 10 benign) were examined. RESULTS: The solid portion of all 39 malignant tumors showed homogeneous or heterogeneous high intensity on DWI, whereas only 3 of the 10 benign tumors (3 thecomas) showed high intensity. The mean (SD) ADC value in the 39 malignant tumors (1.03 [0.19]) was significantly lower than that in 10 benign tumors (1.38 [0.30]). A relatively low ADC (1.08-1.20) in the 3 thecomas may reflect their abundant cellular nature, and the presence of low intensity on T2-weighted images was suggestive for benign fibrous tumor. CONCLUSIONS: Low intensity on DWI with high ADC may suggest benign lesions; however, it may be occasionally difficult to differentiate benign and malignant lesions only on the basis of DWI.

[Comparison of dose distribution on radiographic film and radiochromic film for intensity modulated radiation therapy].

PURPOSE: Radiographic film is generally used for inspection of dose distribution in intensity modulated radiation therapy (IMRT) at many institutions. However, the distribution of filmless systems can be expected to be used increasingly in the future. Therefore, we confirmed the utility of radiochromic film by comparing it with radiographic film that does not need an automatic processor. RESULT: Difference in does measured by radiographic film and radiochromic film tended to increase in the low does area, but it was limited in a range of 1.5%. CONCLUSION: When the dose distribution was verified in a highly accurate radiation therapy such as IMRT, the results suggested that radiochromic film can be useful in addition to radiographic film.

High gamma-aminobutyric acid level in cortical tubers in epileptic infants with tuberous sclerosis complex measured with the MEGA-editing J-difference method and a three-Tesla clinical MRI Instrument.

The purpose of this study was to estimate the gamma-aminobutyric acid (GABA) and glutamate plus glutamine (Glx) concentrations in the cortical tubers of patients with tuberous sclerosis complex (TSC) using the MEGA-editing J-difference method and a stimulated echo-acquisition mode with a short echo time, and to determine which abnormality was more dominant between GABA and Glx in patients with TSC with epilepsy. This study included six patients with TSC (mean age, 4.3 years) and seven control subjects (mean age, 4.8 years). Measurements were obtained with a three-Tesla apparatus and postprocessing was conducted with an LCModel. The GABA level in the cortical gray matter (cgGABA) was calculated as a result of segmentation in voxels and from the literature values for gray and white matter ratios for GABA. Increased GABA and myo-inositol (mI) concentrations and a decreased N-acetyl aspartate (NAA) concentration were observed in the cortical tubers. The cgGABA level, and cgGABA/NAA and cgGABA/Glx ratios were also higher in patients with TSC than in control subjects. No significant difference was found in Glx concentration between patients with TSC and control subjects. Although the number of patients with TSC in this study was small, the increase in GABA and no significant change in Glx were consistent with previous neurochemical studies and support the hypothesis that brain GABA plays a key role in the pathophysiology of epilepsy during the process of neuronal development.

Clear cell adenocarcinoma of the female urethra: magnetic resonance imaging.

Clear cell adenocarcinoma of the female urethra is a rare malignant tumor arising from urethral diverticulum or paraurethral ducts and glands, and extends to the submucosa surrounding the urethra. In the advanced stage, the tumor may involve adjacent organs such as the vagina, and may mimic gynecologic malignancy. We report 2 cases in which magnetic resonance imaging could reveal their urethral origin by detecting the normal urethra within the mass as targetlike appearance on axial T2-weighted image.

Hyperintense uterine myometrial masses on T2-weighted magnetic resonance imaging: differentiation with diffusion-weighted magnetic resonance imaging.

OBJECTIVE: The objective was to determine whether diffusion-weighted imaging (DWI) might be useful in differentiating uterine leiomyomas exhibiting hyperintensity on T2-weighted images from malignant lesions. METHODS: Thirty-four uterine myometrial lesions including 7 malignant tumors and 27 leiomyomas (6 cellular leiomyomas [CLM] and 21 degenerated leiomyomas [DLM]) were evaluated. The apparent diffusion coefficients (ADC) in cellular portions of the lesions were measured (10(-3) mm2/s). RESULTS: All malignant tumors showed high signal intensity on DWI with low ADC (mean [SD], 0.79 [0.26]), which was significantly lower (P < 0.01) than that in benign leiomyomas (1.51 [0.33]). The ADC in CLM (1.18 [0.16]) was significantly lower (P < 0.01) than that in DLM (1.60 [0.30]) and higher (P < 0.05) than that in malignant tumors. CONCLUSIONS: It was difficult to differentiate malignant tumors from leiomyomas on the basis of signal intensity on DWI; however, the ADC measurement may be helpful to distinguish malignant tumors, CLM, and DLM.

Evaluation of initial diffusion-weighted image findings in acute stroke patients using a semiquantitative score.

PURPOSE: We evaluated the usefulness of rating diffusion-weighted images (DWI) using a semiquantitative score modified from the Alberta Stroke Programme Early CT Score (ASPECTS) to predict deterioration of neurological symptoms in patients with hyperacute ischemic stroke who had undergone thrombolytic therapy with recombinant tissue plasminogen activator (rt-PA). MATERIALS AND METHODS: We examined 22 patients with acute stroke (14 men, 8 women, mean age 72.5 years) treated with intravenous rt-PA. All were assessed using the National Institutes of Health Stroke Scale (NIHSS) and underwent emergent magnetic resonance (MR) imaging within 3 hours and 24 hours of stroke onset. Patients were divided into a deteriorated group (16 patients), in which NIHSS scores were increased after thrombolysis, and a non-deteriorated group (6 patients). We compared the DWI score, ASPECTS, and volume of hyperintense ischemic lesion on DWI (DWI volume) of the 2 groups and examined correlations between these scores and initial NIHSS score or DWI volume. RESULTS: The DWI score and ASPECTS tended to be lower in the deteriorated group than the non-deteriorated group. In addition, with a cutoff value

[Comparison with bone scintigraphy and MDCT findings in patients with round focal accumulation on bone scintigraphy].

PURPOSE: This study aimed to compare with bone scintigraphy showed round focal accumulation and Multidetector Row CT (MDCT) findings. METHODS: We obtained 101 patients (mean age 69.2 years; 75 men, 26 women) and 186 diseases. They were examined both MDCT and bone scintigraphy within a month of each other. We classified into two groups (with metastasis and spondylosis) according to their MDCT findings. Bone scintigraphy was estimated on planar image, MDCT was evaluated in three directions with 1 x 1 x 1 mm thickness. RESULTS: We determined 20 metastases cases and 81 of spondylosis. We could not judge abnormal findings on MDCT in 4 patients (1 metastasis, 3 spondylosis); thus, detectability by MDCT was 93.5%. In the spondylosis group, the accumulation lesions were localized on the lower vertebral body in 76 patients (59%), with most showing as osteophytes. In the metastasis group, 11 patients showed more than 1 accumulations, 9 were osteoblastic changes and 10 were lytic. There was a tendency that patients who accumulated more than 1 vertebral bodies (64%) had osteoblastic and irregular distribution and those who accumulated just one body (78%) were lytic and their locations were focused on the lateral side. CONCLUSION: For evaluating bone scintigraphy, MDCT finding was helpful to increase the detectability in bone metastasis. Therefore, we should refer to MDCT finding positively in reading bone scintigraphy.

Ischemic findings of T2*-weighted 3-tesla MRI in acute stroke patients.

BACKGROUND: We compared ischemic findings on gradient echo-type T(2)*-weighted images at 3-tesla MRI (T(2)*WI) in patients with acute ischemia and major vessel occlusion, and stroke patients with lacunar infarction or branch atheromatous disease. METHODS: Our study population consisted of 45 patients with acute stroke. They underwent 3-tesla MRI within 12 h of stroke onset. Included were 24 patients (13 men and 11 women, mean age 68 years) with major vessel occlusion and 21 patients (11 men and 10 women, mean age 69 years) with minor infarction such as lacunar infarcts or branch atheromatous disease. We classified vascular ischemic findings of T(2)*WI into 3 sign categories, i.e. artery susceptibility sign, cortical vessel sign (hypointensity and enlargement of the cortical vessels) and brush sign (hypointensity of vessels in the deep white matter). Decreased intensity in the ischemic parenchyma was designated ischemic tissue sign. We compared regions of interest in the hypoperfused area on flow-sensitive alternating inversion recovery (FAIR) images with our vascular ischemic findings. RESULTS: None of the vascular ischemic signs nor the ischemic tissue sign were found in patients with minor vessel disease. All 24 patients with major vessel occlusion manifested the cortical vessel sign, 23 the brush sign. The area with ischemic vessel signs on T(2)*WI was almost as large or somewhat smaller than the hypoperfused area on FAIR images. Compared to the contralateral side, 14 of 24 patients (58.3%) with major vessel occlusion showed decreased intensity in the ischemic parenchyma (ischemic tissue sign). Region of interest measurements on FAIR images demonstrated greater hypoperfusion in the area classified as ischemic tissue sign on T(2)*WI. CONCLUSIONS: Ischemic vessel signs and the ischemic tissue sign on T(2)*WI at 3 T would be useful to evaluate the extensive ischemia due to major vessel occlusion and may be correlated with the blood-oxygen-level-dependent effect due to increased deoxyhemoglobin. The ischemic tissue sign may be reflective of severe ischemia.

Susceptibility-weighted MRI of endometrioma: preliminary results.

OBJECTIVE: Susceptibility-weighted MRI combines magnitude and phase information from fully velocity-compensated gradient-echo sequences and depicts as signal voids the susceptibility effects caused by local inhomogeneity of the magnetic field. Our objective, based on MRI of 60 pathologically proven ovarian cystic lesions, including 42 endometriomas and 18 nonendometrial cysts, was to evaluate hemosiderin deposition within the walls of endometriomas on susceptibility-weighted MR images. Two radiologists blinded to the final diagnosis retrospectively reviewed the images in consensus. CONCLUSION: On susceptibility-weighted MR images, punctate or curved linear signal voids along the cyst wall were observed in 39 endometriomas (92.9%) and in no nonendometrial cysts. The signal voids were more prominent on 3-T than on 1.5-T images, reflecting the higher sensitivity of 3-T MRI to magnetic susceptibility effects. Thirty-two endometriomas (76.2%) met definitive MRI criteria, that is, hyperintensity on T1-weighted images and hypointensity on T2-weighted images, and 41 endometriomas (97.6%) were correctly diagnosed with susceptibility-weighted MRI.

Prognostic significance of HIF-2alpha expression on tumor infiltrating macrophages in patients with uterine cervical cancer undergoing radiotherapy.

Hypoxia-inducible factor (HIF)-2alpha, a basic helix-loop-helix (bHLH)-PAS protein, is the principal regulator of the hypoxic transcriptional response. An immunohistochemical study reported strong HIF-2alpha expression in the cytoplasm of tumor infiltrative macrophages (TIMs). Thus we assessed the expression of HIF-2alpha in human cervical cancer tissue before radiation therapy and its relationship to the clinical outcome. Seventy three patients with histologically proven primary advanced squamous cell carcinoma of the uterine cervix underwent radiotherapy in Tokushima University Hospital after biopsy specimens were taken. Among 73 specimens stained for HIF-2alpha, 53 (72.6%) exhibited HIF-2alpha immunoreactivity in the TIMs. In only 5 of 73 cases, HIF-2alpha immunoreactivity was observed in the nuclei of tumor cells. The HIF-2alpha positive cell count ratio in TIMs was associated with disease-free survival (DFS) with the worst DFS (p=0.024) being in cases in the group with a high positive cell count ratio. A high HIF-2alpha positive cell count ratio in TIMs increased the risk of local recurrence (p=0.0142). These findings might suggest that the ratio of the HIF-2alpha positive cell in TIMs may be a new predictive indicator for prognosis before radiation therapy for uterine cervical cancer.

Malignant Brenner tumor with transition from benign to malignant components: computed tomographic and magnetic resonance imaging findings with pathological correlation.

We report computed tomographic and magnetic resonance findings of an ovarian malignant Brenner tumor with transition from benign to malignant components. The tumor was demonstrated as a cystic mass with solid mural components. The benign component contained dense calcifications on computed tomography and showed very low intensity on T2-weighted images, whereas the malignant component showed high intensity. The admixture of 2 components may well reflect the pathological feature and may be a diagnostic clue to malignant Brenner tumor.

Ovarian fibromatosis: magnetic resonance imaging findings with pathologic correlation.

Ovarian fibromatosis is a rare benign nonneoplastic condition with ovarian enlargement in young women and characterized by a proliferation of collagen-producing spindle cells surrounding normal ovarian structures. We reported magnetic resonance findings of a case that the affected ovarian parenchyma with follicles was surrounded by very low intense thick fibrous tissue on T2-weighted images such as "black garland" around the ovary. The magnetic resonance findings well reflected the pathological feature of the disease and may be diagnostic.

Ancient schwannoma of the female pelvis.

BACKGROUND: The objective of this article is to define the imaging characteristics of ancient schwannoma, which is a rare variant of benign schwannoma with degenerative changes, arising in the female pelvis simulating ovarian tumors. METHODS: Eleven surgically proven ancient schwannomas of the female pelvis were evaluated retrospectively on the basis of CT and MR findings. RESULTS: Typical intra-pelvic schwannoma was a neurologically asymptomatic large mass, which may situate at presacral or lateral pelvic region with the continuity to the nerve or neural foramen. Ancient schwannomas manifested as encapsulated solid masses with random or eccentric cystic areas, or as cystic masses with marginal crescent-shaped or nodular solid components. Hemorrhagic changes and calcifications were often observed on MRI and CT respectively. To detect ipsilateral normal ovary and to demonstrate centripetal displacement of the adjacent rectum or iliac vessels were helpful to diagnose the tumor as an extra-ovarian mass situated at the extraperitoneal region. CONCLUSIONS: Diagnosis of ancient schwannoma before surgical treatment is important and should be made by its characteristic clinical and imaging findings.

Does partial volume corrected maximum SUV based on count recovery coefficient in 3D-PET/CT correlate with clinical aggressiveness of non-Hodgkin's lymphoma?

OBJECTIVE: There is much controversy about the correlation between the degree of 2-[(18)F]fluoro-2-deoxy-D: -glucose (FDG) uptake and clinical aggressiveness of non-Hodgkin's lymphoma (NHL). In this study, we investigated whether partial volume corrected FDG uptake based on count recovery coefficient in 3D-positron emission tomography (PET)/computed tomography (CT) correlates with the clinical aggressiveness of NHL and improves diagnostic accuracy. METHODS: Forty-two patients with NHL underwent FDG-PET/CT scans (26 aggressive NHLs and 16 indolent ones). Count recovery curve was obtained using NEMA 2001 body phantom. Scan protocol and reconstructive parameters in the phantom study were the same as those in a clinical scan except for emission time. Relative recovery coefficient (RC) was calculated as RC = A/B (A, maximum pixel count of each hot sphere; B, maximum pixel count of greatest sphere). Partial volume corrected maximum count of standardized uptake value (PVC-SUV) was calculated as PVC-SUV = NC-SUV/RC (NC-SUV: non-corrected maximum count of SUV). Three parameters (NC-SUV, PVC-SUV, and size) between aggressive and indolent NHLs were compared. RESULTS: Significant differences were shown in all parameters between aggressive and indolent NHLs. Means +/- SD of NC-SUV, PVC-SUV, and size was as following: NC-SUV (15.3 +/- 6.9, 8.7 +/- 7.0; P < 0.01), PVC-SUV (18.2 +/- 8.1, 12.7 +/- 7.8; P < 0.05), and size (mm, 32.4 +/- 18.3, 21.9 +/- 10.3; P < 0.05). When an NC-SUV of 9.5 was the cutoff for aggressive NHL, the receiver-operating-characteristic (ROC) analysis correctly identified 21 of 26 aggressive ones. Sensitivity and specificity were 81% each, and the positive and negative predictive values were 88% and 72%, respectively. When a PVCSUV of 11.2 was the cutoff, the ROC analysis revealed 81% sensitivity, 63% specificity, and positive and negative predictive values of 78% and 67%, respectively. At a cutoff for aggressive NHL of a size of 27 mm, the ROC analysis revealed 50% sensitivity, 81% specificity, and positive and negative predictive values of 81% and 50%, respectively. The comparison of area under the curve in ROC analyses indicated that NC-SUV showed the greatest diagnostic accuracy (NC-SUV 0.84, PVC-SUV 0.72, and size 0.69). CONCLUSIONS: Diagnostic accuracy of PVC-SUV was inferior to that of NC-SUV. These results suggest that NC-SUV, which contains information on both size and FDG density, provides better differentiation between aggressive and indolent NHLs than PVC-SUV.

Comparison of 3.0-and 1.5-tesla diffusion-weighted imaging in the visibility of breast cancer.

PURPOSE: The aim of this study was to compare diffusion-weighted imaging (DWI) at 3.0 T and 1.5 T by evaluating the apparent diffusion coefficient (ADC) value and visibility of breast cancer in the same patients. MATERIALS AND METHODS: A total of 13 patients (16 lesions) with breast cancer underwent DWI at 3.0 T and 1.5 T. Tumors were classified into two groups based on the lesion size. The ADC values were measured, and visibility of the tumors was scored blindly. RESULTS: No significant difference was found for ADC values between 3.0 T and 1.5 T in either group (P > 0.05). All of the large lesions were visible clearly at both magnetic field strengths, and image scores were not different (P > 0.05). In contrast, small lesions were more clearly visible and had better image scores at 3.0 T than at 1.5 T (P < 0.001). CONCLUSION: Small cancers were more clearly visible on DWI at 3.0 T than 1.5 T.

Effective bladder preservation strategy with low-dose radiation therapy and concurrent intraarterial chemotherapy for muscle-invasive bladder cancer.

PURPOSE: The aim of this study was to evaluate retrospectively the toxicity and response, bladder preservation, and survival of patients with muscle-invasive bladder cancer treated with multimodality therapy consisting of low-dose radiation therapy (RT) and concurrent intraarterial chemotherapy (IACT). METHODS AND MATERIALS: . Between November 1999 and July 2005, a total of 27 consecutive, previously untreated patients with muscle-invasive bladder cancer underwent transurethral bladder tumor resection followed by concurrent low-dose RT and IACT. Patients who achieved a complete response (CR) were followed up closely without further therapy, and patients who did not achieve a CR underwent further treatment. RESULTS: Complete response was achieved in 22 of 27 patients (81%). Of these 22 patients, 7 developed recurrences, and 3 died of their disease. In five patients who did not achieve CR, one died from bone metastases. The 3-year overall survival rate was 81%, with a median follow-up time of 27 months; and 22 of 27 patients (81%) with a preserved bladder were tumor-free at the last follow-up. Three patients (11%) developed grade 3 acute hematological toxicity. CONCLUSION: Multimodality therapy consisting of low-dose RT and concurrent IACT for muscle-invasive bladder cancer can achieve survival rates similar to those in patients treated with radical cystectomy, with successful bladder preservation and minimal adverse effects.