Image quality improvement of single-shot turbo spin-echo magnetic resonance imaging of female pelvis using a convolutional neural network.

We have developed a deep learning-based approach to improve image quality of single-shot turbo spin-echo (SSTSE) images of female pelvis. We aimed to compare the deep learning-based single-shot turbo spin-echo (DL-SSTSE) images of female pelvis with turbo spin-echo (TSE) and conventional SSTSE images in terms of image quality.One hundred five and 21 subjects were used as training and test sets, respectively. We performed 6-fold cross validation. In the training process, low-quality images were generated from TSE images as input. TSE images were used as ground truth images. In the test process, the trained convolutional neural network was applied to SSTSE images. The output images were denoted as DL-SSTSE images. Apart from DL-SSTSE images, classical filtering methods were adopted to SSTSE images. Generated images were denoted as F-SSTSE images. Contrast ratio (CR) of gluteal fat and myometrium and signal-to-noise ratio (SNR) of gluteal fat were measured for all images. Two radiologists graded these images using a 5-point scale and evaluated the image quality with regard to overall image quality, contrast, noise, motion artifact, boundary sharpness of layers in the uterus, and the conspicuity of the ovaries. CRs, SNRs, and image quality scores were compared using the Steel-Dwass multiple comparison tests.CRs and SNRs were significantly higher in DL-SSTSE, F-SSTSE, and TSE images than in SSTSE images. Scores with regard to overall image quality, contrast, noise, and boundary sharpness of layers in the uterus were significantly higher on DL-SSTSE and TSE images than on SSTSE images. There were no significant differences in the CRs, SNRs, and respective scores between DL-SSTSE and TSE images. The score with regard to motion artifacts was significantly higher on DL-SSTSE, F-SSTSE, and SSTSE images than on TSE images. The score with regard to the conspicuity of ovaries was significantly higher on DL-SSTSE images than on F-SSTSE, SSTSE, and TSE images (P < .001).DL-SSTSE images showed higher image quality as compared with SSTSE images. In comparison with conventional TSE images, DL-SSTSE images had acceptable image quality while keeping the advantage of the motion artifact-robustness and acquisition time efficiency in SSTSE imaging.

[Is hyperdynamic therapy possible for elderly patients with vasospasm following subarachnoid hemorrhage?].

BACKGROUND: Recently we have an increased number of elderly patients with subarachnoid hemorrhage (SAH) to be treated. Elderly patients are expected to have a worse cardiac function than that of younger patients. A question arises whether management for elderly patients in the vasospasm period can be performed as safely as it is for younger patients. The aim of this study is to examine the cardiac function of the elderly patients (> or =75 y.o.) with SAH correlated with various complications in the vasospasm period. MATERIALS: We retrospectively analyzed consecutive 356 patients with SAH encountered in our institute since 2000 to 2006. Seventy-three patients (20.5% of all) are 75 or more than 75-year-old. Their mean age is 80.4 +/- 4.43 (16 male, 57 female). Cardiac function was examined by trans-thoracic echocardiography (CTE) in 40 patients (54.8%). RESULT: Average value of their ejection fraction (EF) and rates of perioperative complications were not so different from those of the younger patients. But among patients of > or =75 y.o., certain patients in whom EF was under 0.6 significantly have experienced cardiopulmonary complications and longer hospitalization. In a multiple logistic analyses, only EF is significantly related with cardiopulmonary complications (P = 0.013). CONCLUSIONS: Among elderly SAH patients > or =75 year of age, some have experienced more cardiopulmonary complications than younger patients and have needed longer hospitalization. For such patients hyperdynamic therapy must be carefully carried out. TTE is effective to predispose and help eliminate their cardiopulmonary complications in the pre- and postoperative period.

Absolute quantitation of myocardial blood flow with (201)Tl and dynamic SPECT in canine: optimisation and validation of kinetic modelling.

PURPOSE: 201Tl has been extensively used for myocardial perfusion and viability assessment. Unlike 99mTc-labelled agents, such as 99mTc-sestamibi and 99mTc-tetrofosmine, the regional concentration of 201Tl varies with time. This study is intended to validate a kinetic modelling approach for in vivo quantitative estimation of regional myocardial blood flow (MBF) and volume of distribution of 201Tl using dynamic SPECT. METHODS: Dynamic SPECT was carried out on 20 normal canines after the intravenous administration of 201Tl using a commercial SPECT system. Seven animals were studied at rest, nine during adenosine infusion, and four after beta-blocker administration. Quantitative images were reconstructed with a previously validated technique, employing OS-EM with attenuation-correction, and transmission-dependent convolution subtraction scatter correction. Measured regional time-activity curves in myocardial segments were fitted to two- and three-compartment models. Regional MBF was defined as the influx rate constant (K(1)) with corrections for the partial volume effect, haematocrit and limited first-pass extraction fraction, and was compared with that determined from radio-labelled microspheres experiments. RESULTS: Regional time-activity curves responded well to pharmacological stress. Quantitative MBF values were higher with adenosine and decreased after beta-blocker compared to a resting condition. MBFs obtained with SPECT (MBF(SPECT)) correlated well with the MBF values obtained by the radio-labelled microspheres (MBF(MS)) (MBF(SPECT) = -0.067 + 1.042 x MBF(MS), p < 0.001). The three-compartment model provided better fit than the two-compartment model, but the difference in MBF values between the two methods was small and could be accounted for with a simple linear regression. CONCLUSION: Absolute quantitation of regional MBF, for a wide physiological flow range, appears to be feasible using 201Tl and dynamic SPECT.

Attenuation of ischemia and/or reperfusion injury during myocardial infarction using mild hypothermia in rats: an immunohistochemical study of Bcl-2, Bax, Bak and TUNEL.

The aim of the present study was to determine the beneficial effect of mild hypothermia during ischemia and/or reperfusion injury in myocardial infarction. Sprague-Dawley rats (400 +/- 20 g) were subjected to 30 min occlusion of the left coronary artery followed by 24 h reperfusion. Rats were divided into normothermic (NT; 37 degrees C) and hypothermic (HT; 34 degrees C) groups. In the HT group hypothermia was maintained during coronary occlusion and continued for 30 min following reperfusion. Histological analysis revealed dead cardiomyocytes and polymorphonuclear neutrophil infiltration after 24 h. Myocardial infarction, measured using an image analyzer, showed that the percentage area of infarction was significantly decreased in the HT group. Immunohistochemical analysis was carried out using antibodies against Bcl-2, Bax and Bak. DNA fragments were labeled in situ using the 3'-OH end-labeling method (TUNEL). In the HT group Bcl-2 was induced in many myocytes, whereas Bax and Bak were induced in only a few myocytes. A higher number of TUNEL-positive cells were recorded in the NT group than in the HT group, but these were more thinly scattered in the HT group. The expression pattern revealed that many myocytes could survive at the border zone in the HT group; in contrast, few myocytes in the NT group were able to survive. Our results suggest that mild hypothermia selectively interferes with, and mitigates, reperfusion injury.