Vessel imaging by interferometric phase-contrast X-ray technique.

BACKGROUND: Phase-contrast x-ray imaging using an x-ray interferometer has great potential to reveal the structures inside soft tissues, because the sensitivity of this method to hydrogen, carbon, nitrogen, and oxygen is approximately 1000 times higher than that of the absorption-contrast x-ray method. Imaging of vessels is very important to understand the vascular distribution of organs and tumors, so the possibility of selective angiography based on phase contrast is examined with a physiological material composed of low-atomic-number elements. METHODS AND RESULTS: Phase-contrast x-ray imaging was performed with a synchrotron x-ray source. Differences in refractive index, ddelta, of physiological saline, lactated Ringer's solution, 5% glucose, artificial blood such as pyridoxylated hemoglobin-polyoxyethylene conjugate, and perfluorotributylamine were measured. Because the ddelta of physiological saline has highest contrast, it was used for the phase-contrast x-ray imaging of vessel, and this was compared with absorption-contrast x-ray images. Vessels >0.03 mm in diameter of excised liver from rats and a rabbit were revealed clearly in phase-contrast x-ray imaging, whereas the vessel could not be revealed at all by the absorption-contrast x-ray image. Absorption-contrast x-ray images with iodine microspheres depicted only portal veins >0.1 mm in diameter with nearly the same x-ray dose as the present phase-contrast x-ray imaging. CONCLUSIONS: Phase-contrast x-ray imaging explored clear depiction of the vessels using physiological saline with small doses of x-rays.

Nonoperative assessment of nodal status for locally advanced cervical squamous cell carcinoma treated by radiotherapy with regard to patterns of treatment failure.

PURPOSE: Lymph node metastasis is a major prognostic factor in the treatment of cervical cancer, but its nonsurgical assessment is not necessarily accurate, particularly in small nodes. We evaluated whether node-negative status could be accurately assessed using a low cutoff measure. METHODS AND MATERIALS: The subjects were 84 patients with Stage IIB-IVA cervical squamous cell carcinoma treated by definitive radiotherapy. Nodal status was assessed by CT as negative (<5 mm), possibly positive (5-10 mm), or probably positive (>10 mm). Cause-specific survival and the disease-free rate, including the pelvic recurrence-free and distant metastasis-free rates, were estimated. RESULTS: The cause-specific survival, disease-free rate, and pelvic recurrence-free rate at 5 years were significantly higher for the 32 patients with node-negative disease (83.5%, 86.1%, and 86.1%) and the 17 patients with possibly node-positive disease (59.2%, 93.8%, and 93.8%) than for the 35 patients with probably node-positive disease (32.6%, 22.0%, and 46.8%), respectively. No significant difference was found between negative and possibly node-positive status. In contrast, the distant metastasis-free rate differed significantly among node-negative (96.4%), possibly node-positive (59.3%), and probably node-positive (35.1%) status. CONCLUSION: Node-negative status assessed using a strict cutoff measure may be useful as a strong predictor of cervical cancer being confined to the pelvis.

Assessment of cervical cancer radioresponse by serum squamous cell carcinoma antigen and magnetic resonance imaging.

OBJECTIVE: To investigate the possibility of objective clinical assessment of the radioresponse of cervical cancer via determination of serum squamous cell carcinoma antigen levels and magnetic resonance imaging (MRI)-based estimation of tumor shrinkage. METHODS: The cases of 60 patients undergoing definitive radiotherapy for cervical squamous cell carcinoma (stage I-II: n = 20; stage III-IV: n = 40) were reviewed. Measurements of serum squamous cell carcinoma antigen levels (n = 60), estimated tumor volume on preradiotherapy MRIs (n = 60), and evaluated tumor shrinkage on postradiotherapy MRIs available (n = 30) were taken. The relation between postradiotherapy squamous cell carcinoma antigen level 2 months after the start of radiotherapy and disease recurrence was investigated. Regression analysis of tumor volume measured on MRIs was used to estimate the extent of tumor shrinkage 2 months after the start of radiotherapy. RESULTS: Preradiotherapy squamous cell carcinoma antigen levels correlated significantly with preradiotherapy tumor volumes. Recurrence was identified in 27 patients as distant (n = 19), distant and local (n = 1), local (n = 5), or regional (n = 2). Of 51 patients with elevated preradiotherapy squamous cell carcinoma antigen levels, 33 achieved normalized levels after radiotherapy. Squamous cell carcinoma antigen normalization was associated with a higher recurrence-free survival rate at 2 years (74.3%) than that associated with nonnormalization of squamous cell carcinoma antigen (5.6%, P <.001). The extent of shrinkage ranged from 61% to 100%, and there was no local recurrence. CONCLUSION: Postradiotherapy squamous cell carcinoma antigen status is a useful indicator of clinical outcome, particularly about tumor recurrence. It is not, however, useful for assessing response to radiotherapy. Magnetic resonance imaging is useful for obtaining an objective assessment of radioresponse.

Spectrum of germ cell tumors: from head to toe.

Germ cell tumors (GCTs) occur most frequently in the gonads and are relatively rare in other sites, such as the pineal gland, neurohypophysis, mediastinum, and retroperitoneum. GCTs are thought to originate from primordial germ cells, which migrate to the primitive gonadal glands in the urogenital ridge. Extragonadal GCTs might also originate from these cells when the cells are sequestered during their migration. Pathologic subtypes of GCTs vary, and the prevalence of mixed tumors is high. These factors produce a diversity of radiologic findings and make prospective radiologic diagnosis difficult in many cases. However, similar radiologic findings have been observed in pathologically equivalent tumors in varying sites. Seminomas appear as uniformly solid, lobulated masses with fibrovascular septa that enhance intensely. Nonseminomatous GCTs appear as heterogeneous masses with areas of necrosis, hemorrhage, or cystic degeneration. Fat and calcifications are hallmarks of teratomas, most of which are benign. In immature teratomas, scattered fat and calcification within larger solid components are occasionally seen. These imaging characteristics reflect the pathologic features of each tumor, and histologically similar GCTs at varying sites have similar radiologic features. Knowledge of the pathologic appearances of GCTs and their corresponding radiologic appearances will allow radiologists to diagnose these tumors correctly.

Evaluations of cooling exercised muscle with MR imaging and 31P MR spectroscopy.

PURPOSE: To investigate the effects of cooling human skeletal muscle after strenuous exercise using 31P MR spectroscopy and MR imaging. METHODS: 14 male subjects (mean age +/- SD, 23.8 +/- 2.3 yr) were randomly assigned to the normal (N = 7) or the cooling group (N = 7). All subjects performed the ankle plantar flexion exercise (12 repetitions, 5 sets). Localized 31P-spectra were collected from the medial gastrocnemius before and after exercise (immediately, 30, 60 min, 24, 48, 96, and 168 h) to determine the ratio of inorganic phosphate to phosphocreatine (Pi/PCr) and intracellular pH. Transaxial T2-weighted MR images of the medial gastrocnemius were obtained to calculate T2 relaxation time (T2), indicative of intramuscular water level, before and after exercise (24, 48, 96, and 168 h). In addition, the muscle soreness level was assessed at the same time as 31P-spectra measurements. Fifteen-minute cold-water immersion was administered to the cooling group after exercise and initial postexercise measurements. RESULTS: The control group showed significantly increased T2 from rest at 48 h after exercise (P < 0.05), but the cooling group showed no significant change in T2 throughout this study. Both groups showed a significantly decreased intracellular pH immediately after exercise (P < 0.05). After that, the cooling group showed a significantly greater value than the value at rest or the control group at 60 min after exercise (P < 0.05). For the Pi/PCr, no significant change was observed in both groups throughout this study. The muscle soreness level significantly increased immediately and at 24-48 h after exercise in both groups (P < 0.05). CONCLUSION: The findings of this study suggest that cooling causes an increase in intracellular pH and prevents the delayed muscle edema.

Report of the 15th follow-up survey of primary liver cancer.

In the 15th Nationwide follow-up survey of primary liver cancer, 18,843 newly registered patients (1998-1999) and 18,405 follow-up patients from 791 hospitals in Japan were analyzed. Of the newly registered patients, approximately 95% were patients with hepatocellular carcinoma (HCC) and 3.3% had intrahepatic cholangiocarcinoma (ICC). The patients were assessed using 194 items that were related to epidemiological and clinicopathological factors, diagnosis, and treatment. Furthermore, the survival rates of all of the newly registered patients in the 10th-15th follow-up survey were calculated for each histological type, background factor(s) and treatment, respectively. In patients with hepatocellular carcinoma, the survival rates of patients who underwent hepatectomy, ethanol injection therapy, microwave coagulation therapy, or transcatheter arterial embolization were calculated by tumor size, tumor number, and clinical stage. This follow-up survey will be helpful to assess the progress of research and medical practice in the treatment of primary liver cancer.

Dual double arterial phase dynamic MR imaging with sensitivity encoding (SENSE): which is better for diagnosing hypervascular hepatocellular carcinomas, in-phase or opposed-phase imaging?

The purpose of this study was to investigate the efficacy of sensitivity encoding (SENSE) dynamic magnetic resonance imaging (MRI) with the dual (in-phase and opposed-phase) double arterial phase to detect hypervascular hepatocellular carcinomas (HCCs). MR images of the liver from 44 consecutive patients were obtained. Dynamic MRI with SENSE was performed six times (precontrast, early arterial, late arterial, 1 min, 3 min and 5 min after contrast injection) at 11 s per scan using the gradient recalled echo sequence (TR/TE/flip angle = 168/2.3 and 4.6/70). In-phase and opposed-phase images were obtained simultaneously each scan. For the quantitative analysis, the signal-to-noise ratio (S/N) of HCC and tumor-to-liver contrast-to-noise ratio (C/N) were analyzed for 55 HCCs. The mean S/N of HCCs on in-phase images showed significantly higher values than that on opposed-phase images regarding all phases (P < 0.001). In arterial phases, the mean tumor-to-liver C/N for in-phase images was significantly higher than that for opposed-phase images (P < 0.05). In portal and delayed-phase images, the mean tumor-to-liver C/N in opposed-phase images showed a negative value. In six HCCs with fatty metamorphosis, the mean tumor-to-liver C/N on arterial phase images approached zero in opposed-phase, while it showed a positive value in-phase. In dual double arterial phase dynamic MRI of the liver, in-phase images were superior to opposed-phase images for detecting early enhancement of hypervascular HCCs, while the latter were superior for detecting washout of contrast media from HCCs in the portal and delayed phase. The combination of both images overcomes the difficulty of diagnosing hypervascular HCCs with fatty metamorphosis.

A decidualized endometrial cyst in a pregnant woman: a case observed with a steady-state free precession imaging sequence.

Decidual changes of the ectopic endometrial stroma during pregnancy are well known among pathologists and obstetricians. However, they appear very similar to endometrial cysts with malignant transformation when imaged. Balanced fast field echo (BFFE) is a steady-state free precession imaging sequence and its contrast is decided by the T1/T2 ratio. The authors report a case of a decidualized endometrial cyst in which mural nodules were isointense with the nomotopic decidualized endometrium on T1- and T2-weighted images and BFFE. Isointensity with the nomotopic endometrium is an MR characteristic that can differentiate a decidualized endometrial cyst from malignant transformation. BFFE is a good alternative sequence during pregnancy because of its shorter acquisition time and lower radiofrequency absorption.

Quantification of cerebral metabolites in glioma patients with proton MR spectroscopy using T2 relaxation time correction.

This study was aimed to investigate the significance of absolute concentration of metabolites in glioma patients using proton MR spectroscopy (MRS) with T2 relaxation time correction using three different echo times. The absolute concentrations of metabolites in 7 normal subjects and in 23 gliomas (10 low-grade, 13 high-grade) were obtained by proton MRS using a tissue water signal as an internal standard. The signal intensities of metabolites and tissue water were corrected by T2 relaxation time. In low-grade glioma, the T2 relaxation time of NAA was shorter, and T2 relaxation time of water was prolonged as compared to normal subjects (p < 0.001). In high-grade glioma, the T2 relaxation time of NAA (p < 0.001) and T2 relaxation time of Cr (p < 0.01) were shorter, and T2 relaxation time of water (p < 0.001) was prolonged as compared to normal subjects. Moreover, high-grade gliomas revealed a shorter T2 relaxation time of Cr than low-grade gliomas (p < 0.05). In glioma, NAA and Cr concentration were decreased, and Cho were increased as compared to normal subjects. Moreover, high-grade glioma revealed a significant lower Cr (p < 0.001) and Cho (p < 0.01) concentration compared to low-grade gliomas. Low Cr concentration is the most reliable indicator of malignancy in glioma. Cho concentration did not correlate with malignancy in gliomas.

Non-traumatic postmortem computed tomographic (PMCT) findings of the lung.

PURPOSE: We attempted to obtain postmortem computed tomographic (PMCT) images of the lung in cases of non-traumatic death and describe the results to distinguish usual postmortem findings from those of specific thoracic causes of death. MATERIALS AND METHODS: Our subjects were a total of 150 consecutive non-traumatic cases with cardiopulmonary arrest on arrival who were examined by CT within 2h after certification of death between January 1993 and December 2001. PMCT images of the lung and the frequency of imaging findings (dependent density, ground glass attenuation (GGA), consolidation, pleural effusion, and endotracheal (or endobronchial) air defect) were retrospectively reviewed. Autopsy had been conducted in 16 of the cases. RESULTS: The causes of death and frequency percentages of dependent density, GGA, consolidation, pleural effusion, and endotracheal (or endobronchial) air defect were: 91 cases of acute heart failure (AHF) (69, 66, 24, 11, 14%), 23 cases of aortic dissection (57, 39, 4, 52, 0%), 11 cases of pneumonia (18, 82, 100, 45, 27%), 23 other specified cases (52, 30, 13, 17, 9%), and two unspecified cases (0, 0, 0, 50, 0%), [total respective frequency percentages were (60, 57, 25, 21, 12%)]. Autopsy confirmed that GGA on PMCT in AHF cases corresponded to pulmonary edema. CONCLUSION: When PMCT of the lung shows no other shadows than dependent density, further analysis is necessary to detect the cause of death.

Abnormal retention of 99mTc-TF in a hamster model of cardiomyopathy analyzed by 99mTc-TF and 125I-BMIPP autoradiography.

OBJECTIVE: Enhanced washout of 99mTc-tetrofosmin (TF) has been reported in patients with hypertrophic cardiomyopathy (HCM). Here, using quantitative dual-autoradiography, the relationship between TF retention abnormality and metabolism depicted by 125I-BMIPP uptake was investigated quantitatively in a hamster model of cardiomyopathy. METHODS AND RESULTS: Early and delayed TF images were obtained at 5 min (7 cardiomyopathic and 5 normal hamsters) and 60 min (8 cardiomyopathic and 5 normal hamsters) after injection, respectively. BMIPP image was obtained 5 min after injection. Five cardiomyopathic and 5 normal hamsters were evaluated histologically. Percent uptake of TF and BMIPP in the heart was measured by an auto-well counter. The left ventricular wall was divided into 12 segments, and the relative regional uptake of TF and BMIPP was measured for each segment. Heterogeneity of radioactive distribution was determined by the standard deviation (SD) of radioactive counts in the left ventricular wall on autoradiogram. The uptake of early TF, delayed TF, and BMIPP in cardiomyopathic hamsters was 8.8%, 20.3%, and 25.3% lower than that in normal hamsters, p < 0.05, p < 0.01, and p < 0.001, respectively. In normal hamsters, distribution of radioactivity in all images was homogeneous, and the SD values were about 13. In cardiomyopathic hamsters, heterogeneous distribution was observed on all images, and the degree of heterogeneity was marked on delayed TF and BMIPP images. The SD was 19.7 +/- 1.2 for early TF image, 25.5 +/- 1.4 for delayed TF image, and 31.7 +/- 2.4 for BMIPP image, respectively. A weak linear correlation was observed between the relative regional uptake of the delayed TF and BMIPP in cardiomyopathic hamsters (r = 0.57). Electron microscopy demonstrated ultra-structural changes in mitochondria of cardiomyopathic hamsters. CONCLUSION: Degree of retention abnormality on delayed TF image corresponded to the metabolic abnormality, probably due to mitochondrial dysfunction, depicted on BMIPP imaging.

Ovarian tumor with functioning stroma.

The authors reported two cases with ovarian tumors with functioning stroma. One was an ovarian carcinoid with testosterone-producing stroma and another was an ovarian mucinous cystadenoma with elevated serum level of estrogen. They appeared as multilocular cystic masses with varying signal on MR. This imaging feature was mimicking both those of Sertoli-Leydig tumors with heterologous elements and granulosa cell tumors, which are well known as functioning tumors. It had been reported in pathological literatures that any type of ovarian tumors can show hormonal activity due to functional stroma, although, it is the first report in the radiological literatures.

Radiation-induced liver injury showing low intensity on T2-weighted images noted in Budd-Chiari syndrome.

PURPOSE: Although it is documented that radiation can cause density or intensity changes on computed tomography or MR imaging in the irradiated hepatic parenchyma, few researchers have reported or understood the MR presentation of changes in hepatic parenchyma following radiotherapy in the patient with Budd-Chiari syndrome. The purpose of this study was to investigate the MR appearance of hepatic radiation injury in Budd-Chiari syndrome and to consider the underlying pathophysiology. MATERIALS AND METHODS: The MR examinations of two patients with Budd-Chiari syndrome were compared with those of 11 patients without Budd-Chiari syndrome. The two groups, both of which suffered from hepatocellular carcinoma, underwent 50-72 Gy of proton-beam irradiation during a period of 14-43 days. Examinations including T1- and T2-weighted imaging, superparamagnetic iron oxide-enhanced imaging, and dynamic study were performed 3-10 weeks after the end of irradiation. RESULTS: Radiation-induced hepatic injury was observed as a low-intensity area on T2-weighted images and on delayed phase images of dynamic study in the Budd-Chiari patients, and as iso- or high-intensity areas on both images in the patients without Budd-Chiari syndrome. US-guided needle biopsy from the irradiated area in one patient with Budd-Chiari syndrome revealed mostly necrotic tissue and fibrous tissue. CONCLUSION: These MR features of hepatic radiation injury in Budd-Chiari syndrome were considered to be due to severe hepatic fibrosis.

Dilatation of the heart on postmortem computed tomography (PMCT): comparison with live CT.

PURPOSE: To delineate cardiac structures on postmortem computed tomography (PMCT) and quantitatively to prove dilatation of the heart after death. MATERIALS AND METHODS: Our subjects were 50 PMCT of non-traumatic deaths and 50 CT of living persons (live CT). We measured maximal and minimal diameters of the superior vena cava (SVC) at three levels (upper, middle, and lower), the inferior vena cava (IVC), pulmonary artery (PA), pulmonary vein (PV), right atrium (RA), and left atrium (LA). Then the product of maximal by minimal diameter and the eccentricity were calculated. RESULTS: The maximal and minimal diameters of the heart were significantly longer than those on live CT except for 1) the maximal diameter of the SVC at the upper level and 2) the maximal diameter of the PA. All of the products of maximal by minimal diameter on PMCT were significantly larger than those on live CT. All of the eccentricities decreased significantly after death except LA. CONCLUSION: The heart is dilated on PMCT, and the right side of it dilates toward a round shape.

Hyperattenuating aortic wall on postmortem computed tomography (PMCT).

PURPOSE: To quantitatively evaluate the finding of hyperattenuating aortic wall on postmortem computed tomography (PMCT) and investigate its causes. MATERIALS AND METHODS: Our subjects were 50 PMCT of non-traumatic deaths and 50 CT of living persons (live CT). The ascending aorta at the level of the carina was visually assessed regarding the presence or absence of hyperattanuating aortic wall and hematocrit effect on PMCT and live CT. The diameter, thickness of the aortic wall, and CT number (HU) of the aortic wall and the lumen were also measured. RESULTS: Hyperattenuating aortic wall was detected in 100% of PMCT and 2% of live CT. The diameter of the aortic wall was 2.9 +/- 0.5 cm on PMCT and 3.5 +/- 0.5 cm on live CT, showing a significant difference. The thickness of the aortic wall was 2 mm on PMCT. Hematocrit effect was observed in 46% of PMCT and in none of live CT. With PMCT, there was a significant difference between the CT numbers of the upper and lower half portions of the lumen (19.6 +/- 11.7/30.9 +/- 12.9), whereas, with live CT, there was no such significant difference (37.4 +/- 7.6/38.9 +/- 6.7), with the overall value of 38.2 +/- 6.7. The CT number of the aortic wall was 49.9 +/- 10.9 on PMCT. CONCLUSION: The causes of hyperattenuating aortic wall on PMCT are considered to be increased attenuation due to contraction of the aortic wall, a lack of motion artifact, and decreased attenuation of the lumen due to dilution of blood after massive infusion at the time of cardiopulmonary resuscitation.

MR imaging of epidermoids at the cerebellopontine angle.

The most common location of intracranial epidermoid is the cerebellopontine angle (CPA). The present study compared the visibility of epidermoid at the CPA in various pulse sequences. Seven patients with epidermoid at the CPA underwent conventional MR imaging (T(1)-, T(2)- and proton density-weighted imaging) as well as diffusion-weighted echo-planar imaging. Fast fluid-attenuated inversion recovery (FLAIR) sequences, magnetization transfer contrast (MTC) sequences, and MR cisternography were employed for selected patients. The signal intensity of the lesions relative to cerebrospinal fluid (CSF), the degree of lesion demarcation and the displacement of surrounding structures were evaluated. Proton density-weighted imaging depicted the lesions as hyper-intense to CSF with clearer delineation than T(1)- and T(2)-weighted imaging. Diffusion-weighted imaging depicted all lesions as strongly hyper-intense relative to CSF and brain tissue. FLAIR sequences depicted the lesions with mixed signal intensities but with poor-to-medium demarcation. MTC imaging increased delineation of the lesions to some degree. MR cisternography depicted the lesions as hypo-intense to CSF and clearly showed the anatomical relation to neighboring nerves and vessels. We concluded that diffusion-weighted imaging could specifically reveal an epidermoid at the CPA as a strongly hyper-intense lesion, and that MR cisternography is mandatory for preoperative planning.

Adenomyomatosis with marked subserosal fibrosis and lipomatosis of the gallbladder: mural stratification demonstrated with MR.

The authors reported a case of fundal-type adenomyomatosis in which mural stratification corresponding to histopathological findings was clearly demonstrated with MR imaging. Single-shot fast spin echo images for MR cholangiopancreatography clearly visualized Rokitansky-Aschoff sinuses (RAS), which are a diagnostic clue for this disease. However, mural stratification comprising RAS with muscular proliferation, massive fibrosis and subserosal fat deposition was more precisely demonstrated in T(2)-weighted images obtained with fast spin echo.

MR microscopy of the articular cartilage with a 1.0T permanent magnet portable MR system: preliminary results.

The present study was designed to evaluate the use of a 1.0T portable permanent magnet MR system in obtaining microscopic MR images of the hyaline cartilage in vitro. A clear laminar appearance was demonstrated with this system. In addition, it was possible to demonstrate cartilage surface irregularity, a decrease in cartilage thickness, and T2 alteration by proteoglycan depletion following up to 12 hours of trypsin treatment. In summary, the portable MR system is useful for investigating cartilage in vitro.

[Changes in 1H-MRS in glioma patients before and after irradiation: the significance of quantitative analysis of choline-containing compounds].

The evaluation of the response to radiation therapy in brain tumor patients is a major and an important issue. Although CT and MRI can measure changes in tumor size, it is difficult to use these imaging methods to evaluate the viability or the proliferation activity of a tumor. In this study, we investigated the metabolite changes in glioma patients using 1H-MRS from before to after radiation therapy, to see whether or not early metabolic changes occur during therapy. Seven patients with histologically proven glioma (1 astrocytoma, 1 anaplastic astrocytoma, 2 oligoastrocytoma, 1 oligodendroglioma, 2 glioblastoma) were examined by means of 1H-MRS using a point-resolved spectroscopy (PRESS) sequence with a repetition time of 2,000 ms and echo times of 68 ms, 136 ms and 272 ms. The 1H-MRS was evaluated by both the spectrum pattern and the quantification of the metabolites. As to radiation therapy, each patient received a total dose of 64.8 Gy (1.8 Gy/fraction) with a 10-MeV linear accelerator. The results revealed that the concentration of choline-containing compounds (Cho) was 4.55 +/- 1.08 mmol/kg wet weight before radiation therapy and was reduced to 2.69 +/- 0.56 mmol/kg wet weight (p < 0.01) after radiation therapy. Moreover, both the N-acetylaspartate (NAA) peak and creatine/phosphocreatine (t-Cr) peak were lower after radiation therapy than before. The peaks of both the lipids (Lip) and lactate (Lac) were higher after radiation therapy than before. In conclusion, Cho concentration is thought to be a useful marker for the evaluation of early post-radiation response. The effect of radiation therapy can be evaluated according to the value of Cho. Further long-term MRS study is needed to prove whether or not the decrease of the Cho value in the present study will change before recurrence at later stages.

[Proton MRS in a case of intracerebellar epidermoid].

We report a case of epidermoid, in which proton MR spectroscopy(MRS) provided additional information to MRI. The tumor revealed high signal intensity on T2-weighted images(WI) and low signal intensity on T1 WI. No enhancement was observed. Proton MRS was acquired with the Proton Regional Imaging of Metabolites(PRIME) method(TR/TE/measurements = 2,000 ms/136,272 ms/128 times). Proton MRS revealed lactate(Lac) peak at 1.33 ppm as negative peak at TE 136 ms and positive peak at TE 272 ms. N-acetylaspartate(NAA), creatine/phosphocreatine(Cr) and choline-containing compounds(Cho) were not visible. Lac peak without other peaks such as NAA, Cr, Cho is a unique finding of proton MRS for epidermoid and this could be useful in the differential diagnosis.