Biomedical subjects
Publications and source records attributed to A M Saks.
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The aim of this study was to assess the feasibility of magnetic resonance renography (MRR) using gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) in comparison with conventional radionuclide renography (RR) using technetium-99m-DTPA (99mTc-DTPA). MRR has many advantages over RR, including lack of ionising radiation, increased spatial resolution, and visible background anatomy. By optimising the pulse sequence, we developed an MRR protocol in which signal intensity is linear with Gd-DTPA concentration over a clinically relevant range. Twenty-nine patients and a volunteer were studied using this protocol. Magnetic resonance renography was performed using three different doses of Gd-DTPA: 0.1 mmol kg-1 (n = 13), 0.05 mmol kg-1 (n = 7), and 0.025 mmol kg-1 (n = 9). Each patient was also assessed using radionuclide renography. The resulting renograms were assessed in terms of time to peak signal intensity, signal decrease after peak, and kidney function ratios calculated from both the areas underneath and the slopes of the uptake curves. We have shown that the MR renograms obtained using low dose Gd-DTPA correlate best with the radionuclide renograms. Remaining discrepancies may be explained by variations in the injection procedures (hence in arterial input functions) and the limited coverage of the three MRR slices compared to the whole body projection of RR. Furthermore, at high local concentrations, signal becomes independent of T1 and is dominated by T2.
Moyamoya disease is a rare cerebrovascular condition of uncertain aetiology commonly affecting young persons. The disease is mainly seen in Japanese patients. We report two cases of moyamoya disease in Caucasian women and review the postulated aetiological factors and associated conditions as well as the spectrum of invasive and non-invasive imaging modalities useful in the diagnosis and follow-up of the disease, with particular reference to the developing role of magnetic resonance imaging and angiography.
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A longitudinal field study examined the moderating and mediating effects of self-efficacy on the relationship between training and the adjustment of newcomers during their 1st year of employment. The results provided some support for the hypothesis that initial self-efficacy moderates the relationship between training and adjustment. Training was more strongly related to posttraining self-efficacy, ability to cope, job performance, and intention to quit the profession for newcomers with low levels of initial self-efficacy mediates the relationship between training and adjustment; however, evidence of complete mediation was found only for ability to cope. Posttraining self-efficacy partially mediated the relationships between training and job satisfaction, organizational and professional commitment, and intention to quit the organization and the profession. Research and practical implications of these findings for the training and the socialization of newcomers are discussed.
Eleven patients (five female and six male, aged 6-67 years) with venous angiomas underwent axial and coronal T1-weighted and fast short inversion time inversion-recovery (STIR) magnetic resonance (MR) imaging to assess the full extent of the malformations. Images were assessed subjectively by the authors in a nonblinded study. In all patients, fast STIR images depicted more anatomic detail than did T1-weighted images and depicted venous angiomas more clearly than did contrast material-enhanced CT scans but did not help discrimination of arteries and veins.
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The radiological appearances of active tuberculosis in human immunodeficiency virus (HIV) positive patients was reviewed. A study group of 61 Black HIV positive patients and a control group of 50 Black HIV negative patients were analysed. The chest radiographs of the HIV seropositive group showed a significantly higher percentage of lymphadenopathy (50%), pleural effusions (38%) and miliary (8%) or interstitial patterns (11%), as compared with those in the seronegative group (8%, 20%, 0% and 4% respectively). Cavitation (38%) and atelectasis (31%) were less common in the seropositive group than in the seronegative group (82% in each category). Thus in an endemic TB environment an awareness of this difference in appearances will allow the radiologist to alert the referring clinician to the possibility of concomitant HIV seropositivity.
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