Pancreatic perfusion of healthy individuals and type 1 diabetic patients as assessed by magnetic resonance perfusion imaging.

AIMS/HYPOTHESIS: Loss of pancreatic beta cell mass and function leads to the development of diabetes mellitus. Currently there is no technical way to non-invasively image islet function and mass. Murine models suggest that islets are highly vascularised organs that make a significant contribution to the total pancreatic blood flow. The current study was undertaken to test with arterial spin labelling (ASL) magnetic resonance imaging if islet mass and/or stimulation of human pancreatic islets by hyperglycaemia can differentially increase whole-pancreas perfusion, thereby distinguishing non-diabetic from type 1 diabetic patients. METHODS: We assessed pancreatic blood flow using ASL at baseline, during a hyperglycaemia clamp study (glucose at 11 mmol/l) and during recovery to euglycaemia. RESULTS: Seventeen healthy volunteers and seven type 1 diabetic patients were studied. In healthy volunteers we observed no change in pancreatic blood flow during the three phases of the study. A trend for an increase in blood flow was observed in the two control tissues, the liver and kidney. Similarly, there was no significant difference in blood flow during the three stages (baseline, hyperglycaemia and recovery) in diabetic patients and there was no significant difference observed between diabetic patients and normal volunteers. CONCLUSIONS/INTERPRETATION: Our data suggest that in humans neither increased demand nor islet mass has a substantial influence on pancreatic perfusion. It is possible, however, that the current state-of-the art imaging technology employed in this study might not be sensitive enough to distinguish between a true effect and noise. TRIAL REGISTRATION: ClinicalTrials.gov NCT00280085.

Physical and geometrical modeling for image-based recovery of left ventricular deformation.

Information about left ventricular (LV) mechanical performance is of critical importance in understanding the etiology of ischemic heart disease. Regional measurements derived from non-invasive imaging to assist in assessing this performance have been in use for decades, and certain parameters derived from these measurements often are useful clinically, as they correlate to some extent with gross physiological hypotheses. However, relatively little work has been done to date to carefully understand the relationship of regional myocardial injury to the local mechanical performance of the heart as derived from image data acquired non-invasively for a particular patient in 3 spatial dimensions over time. This paper describes efforts to take advantage of recent developments in 3D non-invasive imaging and biomechanical modeling to design an integrated computational platform capable of assembling a variety of displacement and velocity data derived from each image frame to deform a volumetric model representation of a portion of the myocardium. A brief description of the reasoning behind this strategy an overview of the approach and some initial results are described.

[Heschl's gyrus identification using functional MRI: neurosurgical issue]. / Identification du gyrus de heschl en IRM fonctionnelle.

AIM: Localizing Heschl's gyrus with functional MRI (fMRI) is a particularly difficult challenge due to the noise of the echo planar sequences and the frequent activation of language areas during auditory paradigms. The goal of this study was to search for a paradigm capable of assessing only pure primary auditory cortex activation with fMRI. MATERIAL AND METHOD: Ten healthy adults were studied. Subjects were asked to continuously perform a visual decisional task while passively listening to an ON-OFF randomized paradigm of tones and rhythmic stimuli. Data were analyzed with SPM. RESULTS: Auditory cortex activation was assessed by observing activated pixels in functional images. Due to the distraction effect of the visual decisional task, functional images of pure primary auditory cortex were obtained in all subjects, with strong and selective activation in the Heschl's gyrus. CONCLUSION: This technique, coupled with fMRI data of language areas can be used as a preoperative tool for surgical preplanning in the left superior temporal region. It shows a clear distinction between resectable areas (primary auditory cortex) and not resectable essential areas (language areas).

Picture Quiz: Abdominal Pain in a patient receiving low molecular weight heparin.

A 63 year old lady with known ischaemic heart disease was admitted to hospital with cardiac sounding chest pain. Blood pressure was 161/80 on admission, and full examination was unremarkable. ECG showed ischaemic changes in the inferior leads, and a diagnosis of unstable angina was made. Troponin I was undetectable. She was treated with subcutaneous Enoxaparin 1.5mg/kg and an intravenous nitrate infusion. Her pain settled the following day, allowing the nitrate infusion to be weaned off, although the Enoxaparin treatment was continued, pending a cardiology opinion. On the third day after admission she collapsed on the ward with a blood pressure of 95/59mmHg; examination revealed lower abdominal tenderness with a mass in the right iliac fossa. Blood tests showed that her haemoglobin had dropped by 5 grams/decilitre,she underwent urgent abdominal ultrasound followed by CT.

Picture quiz (answer).

Subcutaneous low molecular weight heparins are widely used in hospitalised patients for the treatment of DVT, pulmonary embolism and acute coronary syndromes, as well as for thromboprophylaxis. Rectus sheath hematoma is a recognised, but sometimes misdiagnosed, complication of treatment with anticoagulant therapy,1 including full and prophylactic doses of low molecular weight heparin.

Independence of the radiobiological oxygen constant, K, and the respiration rate of mammalian cells.

The radiosensitivity, and the radiobiological oxygen-constant K for mouse Ehrlich ascites cells depend on the pre-irradiation growth conditions. Measurements of the oxygen-consumption rate of cells grown by different methods have been made to ascertain whether the differences in radiobiological properties could be associated with different rates of respiration. Inhibition of respiration by sodium amytal had no significant effect on either the radiosensitivity or the estimate of K.

A method for measuring the spatial distribution of tissue oxygen removal rates.

Distributions of oxygen removal rates are measured over cut surfaces of samples of recently excised tissue. The samples are initially equilibrated with a gas of known oxygen tension and the surface is occluded by bringing it into contact with the end of a glass rod which has a number of polarographic electrodes embedded in it. The oxygen removal rate in mm Hg/sec is calculated from the rate of fall of surface oxygen tension. 91 electrodes are arranged in an array with 0.5 mm separation and each gives an estimate of the oxygen removal rate with a spatial resolution of a few hundred microns. An artificial medium of uniform and controllable respiration rate was used to test the system. Spatial variations in oxygen removal rate were demonstrated in some transplantable rodent tumours.

Comparison between the oxygen removal rate and the histological structure of normal and tumour tissues.

A technique has been used to measure distributions of oxygen removal rate, QR, in samples of recently excised tissue where QR is defined as the ratio of the oxygen uptake rate to the oxygen solubility. QR was measured at 91 sampling points across a cross section of tissue of diameter 5 mm. By placing markers in the tissue and using special procedures to obtain sections of the tissue samples it was possible to compare the distributions of QR with the histological structure of the tissues. The overall resolution of the system is about 1/2 mm so that structures of the order of a millimetre or more could be examined. There are considerable inhomogeneities in QR within some normal tissues, for example 4-19 mm Hg/s in rat kidney and 0.4-1.5 mm Hg/s in human cervix. Inhomogeneities in tumour tissues are also associated with the histological structure and examples for the Lewis lung mouse carcinoma show a correlation between QR and regions of viable or necrotic tissue. For a biopsy sample of human carcinoma of the cervix QR correlates with the degree of local infiltration by tumour cells.

The accuracy and spatial resolution of the measurement of tissue oxygen removal rate.

An analysis is presented of factors determining the accuracy and spatial resolution of a method for the estimation of oxygen removal rate in tissues using a multi-cathode electrode placed on the tissue surface. The effect of oxygen consumption by the cathodes is shown to be small for 25-micrometer diameter cathodes, but covering the tissue surface with a thin oxygen oxygen-permeable plastic film can introduce a systematic error into the estimate of removal rate, the size of which depends upon the oxygen diffusion coefficient and solubility in the plastic compared with those in the tissue. Spatial resolution is shown to be adequate for distinguishing changes in removal rate over distances of a few hundred microns, and the averaging of removal rate in the direction normal to the tissue surface is weighted heavily towards the superficial tissue layer.

A pharmacist's audit of antirheumatic drugs.

The results of an audit, by a hospital pharmacist, of antirheumatic drug use at four rheumatology units are presented. Profiles can be developed for each drug which indicate their efficacy and the adverse reaction rate in clinical practice. These can be used to make rational therapeutic choices. A pharmacist can effectively collate such data to provide an unbiased information source.

Pneumocystis carinii pneumonia complicating low dose methotrexate treatment for psoriatic arthropathy.

A case of Pneumocystis carinii pneumonia complicating low dose methotrexate treatment for psoriasis and psoriatic arthropathy is described. This potentially fatal event was probably precipitated by an interaction between methotrexate and concurrent non-steroidal anti-inflammatory drugs, resulting in serious potentiation of the effects of methotrexate.

Rheumatoid arthritis: relation of serum C-reactive protein and erythrocyte sedimentation rates to radiographic changes.

Serum C reactive protein (CRP) levels and erythrocyte sedimentation rates (ESR) were measured in 56 patients with rheumatoid arthritis. Radiographical damage, based on a count of erosions, was significantly more likely to occur when serum CRP and ESR were persistently raised, irrespective of the presence or absence of rheumatoid factor. Measurements of both CRP and ESR were more helpful than either alone, but CRP was probably the more informative. Serial measurements of CRP and ESR provide a reliable means of discriminating between drugs that provide symptomatic relief only and those with a more profound effect in rheumatoid arthritis.

Effect of naproxen on renal haemodynamics in elderly patients with arthritis.

The effects of naproxen on renal haemodynamics were observed in ten elderly arthritic patients who were otherwise healthy and without clinical evidence of renal disease. Glomerular filtration rate (GFR,51Cr-EDTA clearance) and effective renal plasma flow (ERPF, 125I-iodohippurate clearance) were measured after 2 weeks' treatment with naproxen 500 mg twice daily and again after 2 weeks off the drug, in random order. Baseline values for GFR and ERPF were within normal limits (mean 72 ml/min/1.73 m2, 110% predicted and 326 ml/min/1.73 m2, 111% predicted, respectively). On naproxen, ERPF and renal blood flow decreased by 10% and 9%, respectively (-32 ml/min/1.73 m2; p = 0.05 and -49 ml/min/1.73 m2; p less than 0.01). These events produced no untoward clinical effects. Nevertheless, this response might impair the kidney's ability to preserve GFR if a further stress were to supervene. Consequently, temporary withdrawal of non-steroidal anti-inflammatory drugs from elderly patients should be considered in response to intercurrent illness or drug therapy likely to compromise renal blood flow.

A comparison between clinical and laboratory tests in rheumatoid arthritis.

Five clinical measurements (clinical score, articular index, visual analogue pain score, visual analogue function score, grip strength) were compared with two laboratory tests (the erythrocyte sedimentation rate and serum C-reactive protein concentration) in 68 patients with rheumatoid arthritis (RA). Patients treated with nonsteroid anti-inflammatory drugs showed clinical deterioration when treatment was interrupted, followed by improvement on resumption; there was no change in the laboratory tests. Patients treated with remission-inducing drugs (RIDs) had improved clinical measurements and also reduced erythrocyte sedimentation rate and serum C-reactive protein levels. Treatment with RID's led to similar trends in both clinical and laboratory tests, but correlation coefficients between the tests at intervals rarely attained statistical significance. The different response times for each test and probably also errors inherent in clinical measurements introduced sufficient variability to account for the discrepancy. Of the clinical tests, 'clinical score' appeared the most satisfactory.