MR imaging of primary adrenal lymphoma.

We describe a patient with non-Hodgkin's B-cell lymphoma of diffuse large cell type, which involved both adrenal glands without adrenocortical insufficiency. Magnetic resonance showed bilateral adrenal tumors with some enhancing septa.

[Dissection-like artifact on one-second scanning time CT].

Dissection-like artifact (DLA) is noted only on one-second scanning time CT image. It is usually observed in the ascending aorta, and less commonly in the superior vena cava and right pulmonary artery. We evaluated 136 cases of thoracic CT (including 20 cases of heart failure), and examined how often and where the artifact is noted and why it is produced. DLA was noted in the ascending aorta in 99 cases. Among the 99 cases, the same artifacts were also shown in the superior vena cava in 26 cases, and in the right pulmonary artery in 10 cases. DLA was never observed in other great vessels, such as the descending aorta and inferior vena cava. This artifact was not demonstrated in patients with heart failure. We presume that DLA is produced by pulsation of the ascending aorta and pulmonary artery. If the artifact is observed, the patient does not have severe cardiac impairment.

[Correlation analysis between patlak plot and DAR using 11C-methionine PET].

Seven patients were studied with positron emission tomography (PET) using 11C-methionine. All had non-Hodgkin's lymphoma but one, who had Hodgkin's disease. By assuming a simple three-compartment model for dynamic data analysis, we used the graphic method proposed by Patlak et al., where Ki (K2K3/(K1+K3)) was compared with DAR (differential absorption ratio). Trichloroacetate was added to each plasma sample, and the activity of the acid-soluble fraction was counted to eliminate the influence of the protein-bound fraction of injected activity. Patlak data plots, using this acid-soluble fraction as an input factor, showed good linearity over the time of data collection. All tumors showed clear 11C-methionine accumulation. Tumor activity reached almost a plateau within 10 min and was kept at the same level for at least 30 min. Ki and DAR were 0.070 +/- 0.035 and 4.64 +/- 1.85 (mean +/- SD), respectively. There was no apparent correlation between histological type and Ki or DAR, while the correlation efficient between Ki and DAR was 0.875. Our conclusion is that DAR will give almost the same result as dynamic data in the analysis of methionine metabolism using PET.

[Evaluation of compression radiotherapy in pelvic treatment].

In pelvic irradiation, the volume of irradiated small intestine is one of the major factors responsible for both acute and late gastrointestinal complications. In this study, exclusion of the small intestine from the pelvic radiation field was attempted with lower abdominal wall compression and bladder distention in the prone position. The mobility of intrapelvic and several problems associated with this technique were investigated. In our results, the small intestine was effectively moved outside of the whole pelvic radiation field in all but two patients. Treatment interruption of 2 days was observed in only two patients. With the AP/PA opposing field method the abdominal skin dose near the compression pillow was revealed to be higher and the dose at the isocenter was inhomogeneous; thus, a three- or four-field technique is recommended if abdominal wall compression is used.

The functional staging of Duchenne muscular dystrophy using in vivo 31P MR spectroscopy.

We applied 31P magnetic resonance spectroscopy (MRS) for the diagnosis of Duchenne muscular dystrophy (DMD), and evaluated its suitability for early-state DMD diagnosis. The spectral patterns showed typical differences between normal and diseased calf muscle. The signal intensity from each spectrum became weaker with advancing disease stage. We could detect abnormality even at the before imaging modalities.

Radiosensitivity and cell cycle redistribution of cultured human tumour cells during fractionated daily 2-Gy irradiations.

Exponentially growing SQ-5 human lung squamous cell carcinoma cells were irradiated in vitro at 2-Gy per fraction per day continuously for 14 days. The number of total cells continued to increase exponentially till day 5, and reached a plateau level thereafter. The cell cycle distribution changed marginally for the first 5 days, and showed a prominent G2/M accumulation at day 7. Plating efficiencies decreased exponentially with increasing fractionation while the total clonogenic cell number remained constant until day 4. Radiosensitivity at each fraction was stable until day 9, but significantly increased at day 11. A comparison of plating efficiencies between the immediate and 24-h delayed assays revealed that the capacity of cells to spare 2-Gy damage increased with the number of 2-Gy fractions. These results suggest that sublethal damage could accumulate during multifraction daily irradiations, while repair of potentially lethal damage and/or proliferation could rather increase.

Serial water changes in human skeletal muscles on exercise studied with proton magnetic resonance spectroscopy and imaging.

In vivo 1H-magnetic resonance imaging (MRI) enabled us to study the distribution of water in living tissues and to document changes in human skeletal muscles during physical exercise. The purpose of the present study was to determine the total muscle water changes after exercise using water in 1H-MR spectroscopy and to compare these changes to the signal intensity change on T2*-weighted images and/or to the T2 value change. Seven young male volunteers were positioned in a 1.5 T Philips MR imaging system. They were then asked to dorsiflex their ankle joint against a 2 kg weight once every 2 seconds for 2 minutes. The peak height of water declined according to the clearance curve after exercise in all seven cases with the 1H-MRS similar to the signal intensity. The increasing rate at peak height of total muscle water exceeded both the signal intensity and the T2 value because the water peak height on the 1H-MRS included the extracellular water. In addition, we measured the changes in signal intensity in both calf muscles after walking race exercise. The time intensity curves were used to draw a clearance curve for each muscle group after exercise. It was possible to discern which muscle was used most from the T2*-weighted image that was obtained once after exercise.

Tumor blood flow measured using dynamic computed tomography.

RATIONALE AND OBJECTIVES: A method for measuring the tumor blood flow (TBF) by means of dynamic computed tomography (DCT) was devised and investigated. METHODS: Twenty-seven patients with superficial tumors underwent measurement of TBF by the new DCT method. For all of the 27 patients, the thermal clearance method was employed to measure the relative tumor blood flow (RTBF). For 16 patients, TBF was measured by oxygen-15-gas positron-emission tomography (PET). The TBF values measured by DCT were compared with the RTBF by the thermal clearance method and the TBF by PET. RESULTS: The results demonstrated a linear relationship. CONCLUSIONS: The newly devised DCT method yields reliable data in measuring TBF.

[Nontraumatic femoral head necrosis: classification of bone scintigraphic findings and diagnostic value of SPECT following planar imaging].

This study was conducted to determine bone scintigraphic findings in nontraumatic femoral head avascular necrosis and diagnostic value of SPECT imaging following a conventional planar imaging. Forty-three femoral heads in twenty-six cases with idiopathic femoral head necrosis (n = 2), systemic lupus erythematosus (n = 22), aplastic anemia (n = 1), and renal transplantation (n = 1) were studied. The diagnosis for femoral head necrosis was based on magnetic resonance imaging as well as other diagnostic studies in all cases. Scintigraphic findings of planar and SPECT images were classified into six categories: normal (N); cold or decrease (C); partial increase with cold or decrease (PH+C); ring-like increase with a cold center (RH+C); partial increase (PH); diffuse and/or irregular increase (DH). Avascular necrosis was confirmed in twenty-four femoral heads, in which planar and SPECT images showed scintigraphic findings of N (n = 3, 2), C (n = 1, 3), PH+C (n = 2, 8), RH+C (n = 2, 3), PH (n = 9, 2), and DH (n = 7, 6), respectively. Femoral heads without avascular necrosis demonstrated planar and SPECT findings of N (n = 16, 12), C (n = 0, 6), and DH (n = 3, 1), respectively. When considering C, PH+C, and RH+C as diagnostic findings for avascular necrosis, sensitivities of planar and SPECT images were 21% and 58%, and specificities were 100% and 68%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

FDG-PET for predicting the prognosis of malignant lymphoma.

To evaluate the usefulness of FDG-PET as a predictor of prognosis, 34 patients with untreated malignant lymphoma in the head and neck region were studied. After FDG-PET and treatment, they were observed from 15 to 50 months. Tumors which were aggressive and resistant to treatment tended to show high uptake of FDG. The survival rate of patients with high uptake of FDG, DAR > or = 8, was lower than the rate of the other patients. It is considered to be useful to add FDG uptake of the tumor to other prognostic factors for predicting the prognosis.

[Integrated and automated data analysis for neuronal activation studies using positron emission tomography: methodology and applications].

A data analysis method was developed for neuronal activation studies using [15O]water positron emission tomography (PET). The method consists of several procedures including intra-subject head motion correction (co-registration), detection of the mid-sagittal plane of the brain, detection of the intercommissural (AC-PC) line, linear scaling and non-linear warping for anatomical standardization, pixel-by-piexl statistical analysis, and data display. All steps are performed in three dimensions and are fully automated. Each step was validated using a brain phantom, computer simulations, and data from human subjects, demonstrating accuracy and reliability of the procedure. The method was applied to human neuronal activation studies using vibratory and visual stimulations. The method detected significant blood flow increases in the primary sensory cortices as well as in other regions such as the secondary sensory cortex and cerebellum. The proposed method should enhance application of PET neuronal activation studies to the investigation of higher-order human brain functions.

FDG-PET for the evaluation of tumor viability after anticancer therapy.

To evaluate positron emission tomography with 18F-fluorodeoxyglucose (FDG-PET) as an diagnostic tool to determine tumor viability after anticancer therapy, fourteen patients were examined by FDG-PET after the end of the treatment. The lesions with residual viable tumor cells showed higher uptake of FDG than surrounding normal soft tissue. The lesions, in which tumor viability was lost or very low, showed higher uptake of FDG in four cases and similar uptake to normal soft tissue in three cases. The residual increased uptake of FDG was considered to be caused by remaining tumor cells and/or inflammatory reaction to anticancer treatment. FDG-PET after anticancer treatment should be interpreted by considering the reaction due to the treatment and the partial volume artifact of PET caused by the limited spatial resolution.

[MR lymphography: first application to human].

First clinical trial of MR lymphography is described. The subjects were two normal volunteers. The contrast agent was cideferron, which was an iron colloid. We obtained MR images of the inguinal lymph nodes before and after subcutaneous injection of the agent in the dorsal feet. As a result, the signal intensities on T2 weighted images remarkably decreased at two hours after injection and kept low until three months after. Although pigmentation around the injection site was observed, it was gradually fading within six months. In conclusion, MR lymphography with cideferron can be applied clinically.

[Tumor blood flow measured by dynamic CT].

A method of measuring tumor blood flow by dynamic CT (DCT) was devised, and the reliability of data obtained by the new method was investigated. The subjects were 16 patients with superficial tumors who underwent measurement of tumor blood flow by both the new DCT-based method and 15O gas positron emission tomography (PET). The results showed that tumor blood flow as measured by the new DCT-based method was about 1.2 times greater than that measured by PET, and both data yielded a straight line passing almost through the origin (proportional relationships); the correlation coefficient was 0.836. On the basis of these studies, it was concluded that the newly devised DCT-based method yields reliable data in the measurement of tumor blood flow.

[Fat suppression failure artifacts at the susceptibility interface on frequency selective fat suppression MR imaging in the head and neck].

Fat suppression MR imaging is a valuable technique mainly used for the orbit, head and neck, and spine, where the high signal from fat can often obscure adjacent pathology. Fat suppression failure artifact manifested as a high signal area without geographic distortion. The purpose of this study was to investigate the frequency and common location of these artifacts in clinical MR imaging and to caution against their misinterpretation. Fat suppression MR imaging of the head and neck was performed in 30 consecutive patients. The artifact was found in the orbital floor (57%), the skull base (10%), and subcutaneous fat (10%), where the air-fat interface is parallel to the static magnetic field direction. The fat signal in the air-fat interface perpendicular to the static magnetic field was well suppressed. This artifact was independent of the duration of TE, frequency/phase encoding direction, and the strength of gradient amplitude, and appeared to be related to the amount of surrounding air. This may simulate pathology if fat suppression is only performed following Gd-DTPA administration. The radiologist should be aware of the presence of artifact by considering the geographic relation to the static magnetic field.

[Evaluation of the cases of benign disease with high accumulation on the examination of 18F-fluorodeoxyglucose PET].

In this study 39 cases of abdominal benign disease were examined by PET using 18F-fluorodeoxyglucose (FDG), and 11 cases of them (i.e. 4 cases of liver abscess, 1 of pelvic abscess, 1 of omental abscess, 2 of chronic pancreatitis, 1 of inflammatory pseudotumor of liver, 1 of retroperitoneal leiomyoma and 1 of solid and cystic tumor of pancreas) which showed as high accumulation of FDG as malignant lesion were investigated of their clinical and pathological feature. We used Ci/Cp ratio as index to express the accumulation of FDG in the lesion, which was calculated from radioactivities of the lesion (Ci) and the plasma (Cp) at 60 mins after injection of FDG. The Ci/Cp ratio of the 11 cases was 3.64 +/- 0.77. The pathological feature of the 9 inflammatory cases was high accumulation of inflammatory cells and that of the 2 benign tumor cases was solid proliferation of tumor cells. The serum of the 9 inflammatory cases showed high CRP value. It was considered that the high accumulation of FDG in inflammatory lesions was due to piles of FDG uptake of the many inflammatory cells, while the 2 benign tumors of high accumulation were considered that the tumor cell had as high glucose metabolism as malignancies.

MRI of soft-tissue lesions: opposed-phase T2*-weighted gradient-echo images.

We evaluated the ability of opposed-phase T2*-weighted gradient-echo (T2*GE) MRI to demarcate soft tissue lesions. The series contained 37 cases, including 18 benign tumors, 8 malignant tumors, and 11 miscellaneous nonneoplastic soft-tissue lesions. Images were obtained on a 0.5 T magnet with T2*GE imaging (TR/TE 300/22 ms, 20 degrees). Results were compared with those of T1-weighted SE images (500/20-40) and T2-weighted SE (T2SE) images (2,000/80). The T2*GE images were similar to T2SE images with respect to the signal behavior and internal architecture of the masses in many cases. In some instances, they were better than T2SE images in delineating the lesions and adjacent fat tissue, in delineating the lesions and adjacent small vessels, and in depicting special features such as hemosiderin deposits. They were inferior to T2SE images in delineating the lesions and adjacent muscles. Because of reduced lesion-muscle delineation, T2*GE images can not be substituted for T2SE images in the evaluation of soft-tissue lesions, but are useful as an adjunct in some cases.

[Correlation 111In-labeled leukocyte scintigraphy with clinical and laboratory findings].

This study was evaluated relationship 111In-labeled leukocyte scintigraphy and clinical information and laboratory findings in twenty-four patients with bone infection and thirty-five patients with abdominal infection. Fifty-nine scintigrams were retrospectively reviewed and classified into positive or negative results. As the laboratory findings, C-reactive protein (CRP) level, erythrocyte sedimentation rate (ESR) at sixty minutes, and peripheral blood leukocyte counts (WBCC) were evaluated. Clinical information such as presence of fever and administration of antibiotics was also compared. No significant relationship between the scintigraphic results and clinical as well as laboratory findings was observed in bone infection patients. CRP levels in positive scintigraphic patients were significantly higher than those in negative scintigraphic patients in the abdominal infection group, otherwise the other indices were not correlated with the scintigraphic results. A few patients with slightly increased CRP (mostly chronic cases) did not show positive scintigrams, suggesting an increased false negative rate of leukocyte scintigraphy in such circumstances. These results suggest that it is inappropriate to determine the application of leukocyte scintigraphy depending on clinical as well as laboratory findings, and leukocyte scintigraphy would yield additional information different from other indices when evaluating inflammatory foci.

Optimization of Butterworth filter for brain SPECT imaging.

A method has been described to optimize the cutoff frequency of the Butterworth filter for brain SPECT imaging. Since a computer simulation study has demonstrated that separation between an object signal and the random noise in projection images in a spatial-frequency domain is influenced by the total number of counts, the cutoff frequency of the Butterworth filter should be optimized for individual subjects according to total counts in a study. To reveal the relationship between the optimal cutoff frequencies and total counts in brain SPECT study, we used a normal volunteer and 99mTc hexamethyl-propyleneamine oxime (HMPAO) to obtain projection sets with different total counts. High quality images were created from a projection set with an acquisition time of 300-seconds per projection. The filter was optimized by calculating mean square errors from high quality images visually inspecting filtered reconstructed images. Dependence between total counts and optimal cutoff frequencies was clearly demonstrated in a nonogram. Using this nomogram, the optimal cutoff frequency for each study can be estimated from total counts, maximizing visual image quality. The results suggest that the cutoff frequency of Butterworth filter should be determined by referring to total counts in each study.

Large epidermal cyst involving the ischiorectal fossa: MR demonstration.

A large subcutaneous mass was noted in the buttock of a 79-year-old man. Computed tomography (CT) and magnetic resonance imaging (MRI) showed a thin-walled cystic mass that involved the ischiorectal fossa. The content appeared hyperintense on T1-weighted images. T2-weighted images demonstrated a considerable amount of debris. At surgery an epidermal cyst with markedly keratinized squamous epithelium was found. It contained much keratin and cholesterin.