Imaging diagnosis of aortic stenosis.

Aortic valve stenosis (AS) is the commonest primary valve disorder with increasing prevalence with age. Trans-thoracic echocardiogram is the main imaging technique used to diagnose AS, but discrepancy in diagnosis has been described in almost one third of cases. Other imaging methods, particularly electrocardiogram (ECG)-gated computed tomography, have now emerged to further clarify the diagnosis of AS by both demonstrating the degree of calcification in the valve as well as aortic valve area. Cardiac magnetic resonance imaging allows accurate quantification of ventricular function and evaluation of the myocardium. This paper provides a comprehensive review of the diagnosis of AS for the radiologist.

Involvement of histamine and histamine H2 receptors in nicotinamide-induced differentiation of human amniotic epithelial cells into insulin-producing cells.

OBJECTIVE AND DESIGN: Human amniotic epithelial cells (HAEC) resemble stem cells in their ability to differentiate into all three germ layers: endoderm, mesoderm, and ectoderm. Histamine receptors are expressed on HAEC. We examined the influence of histamine, and H(1) and H(2) antagonists on the generation of pancreatic islet beta-like cells from HAEC. MATERIALS AND METHODS: HAEC were isolated after term pregnancies (N = 12) and cultured for 14 days with nicotinamide (10 mM) in normoxia. Altogether, 72 cultures were established. Histamine (100 microM) effects were investigated with mepyramine (10 microM) or cimetidine (10 microM). After 7 and 14 days, the mean concentration of C-peptide (MCCP) in the culture medium was measured immunoenzymatically as a marker of pancreatic differentiation. RESULTS: MCCP was approximately threefold higher on day 14, compared to day 7. Histamine significantly increased MCCP, and more evident differences were observed after 7 days of culture than after 14 days. The mean percent increase +/-SEM in MCCP amounted to 142.19 +/- 21.7 and 79.03 +/- 12.35 compared to the controls on day 7 and 14, respectively. H(2) blockade significantly reduced histamine-related increase in MCCP, both on day 7 and 14 by 88.7 +/- 14.3 and 39.2 +/- 12.4%, respectively. H(1) receptor antagonist did not affect MCPP. CONCLUSION: Nicotinamide-induced pancreatic differentiation of HAEC into beta-like cells may be augmented, probably at its earlier stage, by histamine acting via H(2) receptors.

Imaging features of isolated unilateral pulmonary artery agenesis presenting in adulthood: a review of four cases.

AIM: To highlight the variation in clinical manifestations, imaging and management of four cases of unilateral pulmonary artery agenesis presenting in adulthood. METHOD: Four patients with unilateral pulmonary artery agenesis were referred to our institution between 1995 and 2005. They underwent a series of investigations, including chest radiography, echocardiography, ventilation perfusion scintigraphy, angiography, computed tomography (CT) and magnetic resonance imaging (MRI). RESULTS: Two of the four patients had absence of the right main pulmonary artery, whilst the remaining two patients had absence of the left main pulmonary artery. One patient showed a restrictive defect on pulmonary function tests. Two patients who had ventilation perfusion scintigraphy showed absent perfusion and reduced ventilation on the affected side. Angiography (where performed), CT and MRI confirmed the anatomy and the presence of multiple collaterals. Bronchiectasis was demonstrated on CT in two patients, with one also demonstrating a mosaic attenuation pattern. One patient had an incidental lung tumour on the side of the agenesis, which was diagnosed as a chondroid hamartoma on histology. Three of the four patients eventually underwent resection of the affected lung. CONCLUSION: Isolated unilateral pulmonary artery agenesis has a non-specific presentation. Awareness of this condition can lead to earlier diagnosis, with cross-sectional imaging making an important contribution.

Renal arteriography using gadolinium enhanced 3D MR angiography--clinical experience with the technique, its limitations and pitfalls.

Gadolinium enhanced 3D MR angiography (MRA) is becoming a widely accepted technique for imaging the vascular system. We set out to evaluate its accuracy and reliability in visualization of renal arteries in the clinical setting. Gadolinium enhanced MRA was performed in 15 potential live renal donors and 26 patients suspected of having renal artery stenosis who were referred for digital subtraction angiography (DSA). MRA was performed on a 1.5 T MR scanner in a single breath hold. Images from each study were prospectively analysed for demonstration of number of main and accessory renal arteries and degree of renal artery stenosis in a double blind fashion. All the main and accessory arteries were visualized on MRA in the renal donor group, but in one case a branch was not identified owing to breathing artefact. In one case, an extrarenal vascular anomaly was not demonstrated on MRA. In the renal artery stenosis group, sensitivity, specificity and negative predictive values of 96%, 93% and 96% were obtained for clinically significant stenosis (>50%). Gadolinium enhanced MRA proved to be a useful technique in demonstration of renal arterial anatomy and grading of renal artery stenosis. However, we encountered some pitfalls and limitations of the technique during the process. It is important to be aware of these before accepting it as the sole technique in clinical practice.

A prospective comparison of brain contrast characteristics and lesion detection using single-shot fast spin-echo and fast spin-echo.

MRI is limited by movement artefact, even with current imagers, when examining a restless or claustrophobic patient. We prospectively analysed the images of 92 patients produced by a single-shot fast spin-echo (SSFSE) pulse sequence and compared them with conventional (FSE) and reduced-time fast spin-echo (RT-FSE) techniques, with regard to lesion detection and movement artefact in brain imaging. Images obtained in each case were independently reviewed and scored for overall diagnosis, number of lesions detected, and movement artefact. FSE showed 1217 lesions, RT-FSE 1137, and SSFSE 1044. This discrepancy arose mainly in patients with multiple sclerosis or small-vessel disease, since with SSFSE we were less able to separate small, adjacent low-contrast lesions than with FSE. Arbitrary movement scores were 36, 25 and zero respectively. There were, however, no clinically significant differences in overall diagnosis between the three techniques. SSFSE thus proved a reliable, fast, accurate method for obtaining T2-weighted images, and may be of particular use in the restless, claustrophobic or obtunded patient.

Triploidy: antenatal sonographic features with post-mortem correlation.

A retrospective study was performed comparing the antenatal ultrasound (US) scan features with post-mortem findings in 20 triploid fetuses surviving beyond the first trimester. US scans showed a range of abnormalities including oligohydramnios (60 per cent of cases), intra-uterine growth retardation (IUGR, 55 per cent), central nervous system (CNS) abnormalities (45 per cent), and placental abnormalities (55 per cent). There were obstetric complications in 30 per cent of cases. Post-mortem examinations confirmed these findings but also demonstrated additional anomalies including facial dysmorphism, limb abnormalities (syndactyly, talips equinovarus and thigh muscle hypertrophy), and anomalies of cardio-vascular, respiratory and genito-urinary system. The placenta was normal in 16 per cent of cases, enlarged with cystic change in 47 per cent, small in 32 per cent and infarcted in 5 per cent of cases. Various factors including oligohydramnios, abnormal fetal position, less sophisticated equipment in mid-1980s and relative inexperience of early observers contributed to the reduced sensitivity of US scans in diagnosis of various defects. However, triploidy should be considered in all cases showing early second-trimester IUGR with or without oligohydramnios, a major CNS abnormality and/or an enlarged placenta with or without changes of partial hydatidiform mole. As triploidy is associated with increased obstetric complications, fetal karyotyping should be offered to confirm the diagnosis so that appropriate obstetric intervention can be instituted.