Radiation medicine最新文献

Purpose: We evaluated the efficacy of using the apparent diffusion coefficient (ADC) to differentiate soft tissue tumors.

Materials and methods: We examined 88 histologically proven tumors (44 benign, 8 intermediate, 36 malignant) using diffusion-weighted magnetic resonance images. Images of the tumors were obtained using a single-shot, spin-echo type echo-planar imaging sequence. The tumors were classified histologically as myxoid or nonmyxoid. We then compared the ADC values of the myxoid and nonmyxoid tumors; the benign and malignant myxoid tumors; and the benign, intermediate, and malignant nonmyxoid tumors.

Results: The mean ADC value of the myxoid tumors (2.08 +/- 0.51 x 10(-3) mm(2)/s) was significantly greater than that of the nonmyxoid tumors (1.13 +/- 0.40 x 10(-3) mm(2)/s) (P < 0.001). There was no significant difference in the mean ADC values between benign myxoid tumors (2.10 +/- 0.50 x 10(-3) mm(2)/s) and malignant myxoid tumors (2.05 +/- 0.58 x 10(-3) mm(2)/s). The mean ADC value of benign nonmyxoid tumors (1.31 +/- 0.46 x 10(-3) mm(2)/s) was significantly higher than that of malignant nonmyxoid tumors (0.94 +/- 0.25 x 10(-3) mm(2)/s) (P < 0.001).

Conclusion: The ADC value might be useful for diagnosing the malignancy of nonmyxoid soft tissue tumors.

Malignant mucosal melanoma is a rare condition. Although the head and neck region is the most common site for mucosal melanoma, a melanoma arising in the eustachian tube is rare. Here we present a case of mucosal melanoma arising in the right eustachian tube.

A single coronary artery is a rare and potentially serious anomaly. We present the case of a 54-year-old woman with chest pain predominantly at rest. A single coronary artery was demonstrated by 64-row multidetector computed tomography (CT) imaging, which is useful for the diagnosis and classification of coronary anomaly. In our case, no coronary artery stenosis was demonstrated on CT angiographic images, and totally occlusive coronary spasm was confirmed by intracoronary infusion of acetylcholine.

Purpose: The aim of this study was to evaluate the usefulness of computer-aided detection (CAD) in diagnosing early colorectal cancer using computed tomography colonography (CTC).

Materials and methods: A total of 30 CTC data sets for 30 early colorectal cancers in 30 patients were retrospectively reviewed by three radiologists. After primary evaluation, a second reading was performed using CAD findings. The readers evaluated each colorectal segment for the presence or absence of colorectal cancer using five confidence rating levels. To compare the assessment results, the sensitivity and specificity with and without CAD were calculated on the basis of the confidence rating, and differences in these variables were analyzed by receiver operating characteristic (ROC) analysis.

Results: The average sensitivities for the detection without and with CAD for the three readers were 81.6% and 75.6%, respectively. Among the three readers, only one reader improved sensitivity with CAD compared to that without. CAD decreased specificity in all three readers. CAD detected 100% of protruding lesions but only 69.2% of flat lesions. On ROC analysis, the diagnostic performance of all three readers was decreased by use of CAD.

Conclusion: Currently available CAD with CTC does not improve diagnostic performance for detecting early colorectal cancer. An improved CAD algorithm is required for detecting flat lesions and reducing the false-positive rate.

Purpose: The aim of this study was to analyze microvas-cularity after reperfused acute myocardial infarction (AMI) using the maximum slope method of contrastenhanced cardiac magnetic resonance imaging (CMR).

Materials and methods: CMR and resting (201)T1 single photon emission computed tomography (SPECT) images were obtained in 30 consecutive patients after reperfused AMI and 10 controls. After bolus injection of gadolinium diethylenetriamine pentaacetic acid, first-pass CMR images were obtained using the True-FISP sequence. Time-intensity curves were generated by measuring the signal intensity in the myocardium and left ventricle. The arterial input function was obtained from the left ventricular time-intensity curve. On the basis of the maximum slope method, the microvascular index (MVI) was calculated by dividing the maximum initial upslope of the myocardium by the initial upslope of the left ventricle.

Results: The MVI was significantly lower in the segments related to the occluded coronary artery. MVIs in segments with (201)Tl uptake of 50%-59% of peak were significantly lower than in those with (201)Tl uptake of 60%-69%. MVIs in segments with (201)Tl uptake of <50% of peak were significantly lower than in those with (201)Tl uptake of 50%-59%.

Conclusion: This study presents a method that directly assesses microvascularity after reperfused AMI.

Purpose: The aim of this study was to clarify the radiosensitivity of intratumor total cells and quiescent (Q) cells in vivo to accelerated carbon ion beams compared with gamma-ray irradiation.

Materials and methods: Squamous cell carcinoma (SCC) VII tumor-bearing mice received continuous administration of 5-bromo-2'-deoxyuridine (BrdU) to label all intratumor proliferating (P) cells. They then were exposed to carbon ions (290 MeV/u) or gamma-rays. Immediately after and 12 h after irradiation, immunofluorescence staining for BrdU was used to assess the response of Q cells in terms of micronucleus frequency. The response of the total (P + Q) tumor cells was determined from the tumors not treated with BrdU.

Results: The apparent difference in radiosensitivity between total and Q cell populations under gamma-ray irradiation was markedly reduced with carbon ion beams, especially with a higher linear energy transfer (LET) value. Clearer recovery in Q cells than in total cells through delayed assay under gamma-ray irradiation was efficiently inhibited by carbon ion beams, especially those with a higher LET.

Conclusion: In terms of the tumor cell-killing effect as a whole, including intratumor Q cells, carbon ion beams, especially with higher LET values, were extremely useful for suppressing the dependence on the heterogeneity within solid tumors as well as depositing the radiation dose precisely.

We report the case of a 64-year-old man with migrainous infarction, giving special attention to chronological changes in neuroimaging findings. Five days after the onset, diffusion-weighted imaging showed slightly high intensity, and the apparent diffusion coefficient map showed increased diffusion in the right occipital lobe, which indicated vasogenic edema. Perfusion magnetic resonance imaging (MRI) and MR angiography demonstrated hyperperfusion of the ipsilateral hemisphere. Follow-up MRI showed irreversible brain damage. These images may reflect chronological changes in cerebral edema due to prolonged hyperperfusion with migraine.

Purpose: The aim of this study was to establish functional computed tomography (CT) imaging as a method for assessing tumor-induced angiogenesis.

Materials and methods: Functional CT imaging was mathematically analyzed for 14 renal cell carcinomas by means of two-compartment modeling using a computer-discretization approach. The model incorporated diffusible kinetics of contrast medium including leakage from the capillary to the extravascular compartment and back-flux to the capillary compartment. The correlations between functional CT parameters [relative blood volume (rbv), permeability 1 (Pm1), and permeability 2 (Pm2)] and histopathological markers of angiogenesis [microvessel density (MVD) and vascular endothelial growth factor (VEGF)] were statistically analyzed.

Results: The modeling was successfully performed, showing similarity between the mathematically simulated curve and the measured time-density curve. There were significant linear correlations between MVD grade and Pm1 (r = 0.841, P = 0.001) and between VEGF grade and Pm2 (r = 0.804, P = 0.005) by Pearson's correlation coefficient.

Conclusion: This method may be a useful tool for the assessment of tumor-induced angiogenesis.

Purpose: To evaluate the possibility of selective hyperthermia following transcatheter arterial embolization (TAE) with ferucarbotran using a newly developed inductive heating (IH) device.

Materials and methods: Twelve Japanese white rabbits were separated into four groups: those treated with TAE using a mixture of ferucarbotran and lipiodol (F-L group); those treated with ferucarbotran and gelatin sponge powder; those treated with saline and lipiodol; and a control group. These four groups received IH. Nine rabbits with renal VX2 carcinoma were separated into three groups: IH after TAE (IH-TAE tumor), TAE without IH (TAE tumor), and no treatment (control tumor). The temperature of the tumor was kept at 45 degrees C for 20 min. The therapeutic effect was pathologically evaluated by TUNEL staining.

Results: In the heating rates of the kidney, the F-L group showed significantly greater values than the group in which iron was not used. In the IH-TAE tumor group, tumors could be selectively heated. In TUNEL staining, the IH-TAE tumor and TAE tumor groups showed significantly greater values of apoptosis rate than in the control tumor group.

Conclusion: IH following TAE with a mixture of ferucarbotran and lipiodol was capable of inducing selective hyperthermia with our device. However, further investigation is needed to confirm its safety and effectiveness in the treatment of malignant neoplasms in humans.

Purpose: We investigated the correlation between abnormal perfusion areas by computed tomography perfusion (CTP) study of hyperacute stroke patients and the final infarction areas after intraarterial catheter thrombolysis.

Materials and methods: CTP study using the box-modulation transfer function (box-MTF) method based on the deconvolution analysis method was performed in 22 hyperacute stroke patients. Ischemic lesions were immediately treated with catheter thrombolysis after CTP study. Among them, nine patients with middle cerebral artery (MCA) occlusion were investigated regarding correlations of the size of the prolonged mean transit time (MTT) area, the decreased cerebral blood volume (CBV) area, and the final infarction area.

Results: Using the box-MTF method, the prolonged MTT area was almost identical to the final infarction area in the case of catheter thrombolysis failure. The decreased CBV areas resulted in infarction or hemorrhage, irrespective of the outcome of recanalization after catheter thrombolysis.

Conclusion: The prolonged MTT areas, detected by the box-MTF method of CTP in hyperacute stroke patients, included the area of true prolonged MTT and the tracer delay. The prolonged MTT area was almost identical to the final infarction area when recanalization failed. We believe that a tracer delay area also indicates infarction in cases of thrombolysis failure.