Urolithiasis is prevalent and associated with reduced bone mineral density in ß-thalassaemia major.

Asymptomatic urolithiasis is common and of mixed composition in patients with ß-thalassaemia major. Twenty-seven subjects were imaged using dual-energy computer tomography to determine the presence and composition of urolithiasis. The prevalence of urolithiasis was 59% and affected patients generally had multiple stones, often with more than one component: struvite (33%), calcium oxalate (31%) and cystine (22%). Hypercalciuria was present in 78% of subjects and calcium-containing urolithiasis was associated with reduced femoral neck Z scores.

Radiation dose reduction using a neck detection algorithm for single spiral brain and cervical spine CT acquisition in the trauma setting.

Cervical spine injuries occur in 4-8 % of adults with head trauma. Dual acquisition technique has been traditionally used for the CT scanning of brain and cervical spine. The purpose of this study was to determine the efficacy of radiation dose reduction by using a single acquisition technique that incorporated both anatomical regions with a dedicated neck detection algorithm. Thirty trauma patients for brain and cervical spine CT were included and were scanned with the single acquisition technique. The radiation doses from the single CT acquisition technique with the neck detection algorithm, which allowed appropriate independent dose administration relevant to brain and cervical spine regions, were recorded. Comparison was made both to the doses calculated from the simulation of the traditional dual acquisitions with matching parameters, and to the doses of retrospective dual acquisition legacy technique with the same sample size. The mean simulated dose for the traditional dual acquisition technique was 3.99 mSv, comparable to the average dose of 4.2 mSv from 30 previous patients who had CT of brain and cervical spine as dual acquisitions. The mean dose from the single acquisition technique was 3.35 mSv, resulting in a 16 % overall dose reduction. The images from the single acquisition technique were of excellent diagnostic quality. The new single acquisition CT technique incorporating the neck detection algorithm for brain and cervical spine significantly reduces the overall radiation dose by eliminating the unavoidable overlapping range between 2 anatomical regions which occurs with the traditional dual acquisition technique.

Effects of electrocardiogram gating on CT pulmonary angiography image quality.

INTRODUCTION: Pulmonary embolism (PE) is the third most common cause of death from cardiovascular disease. Computed-tomographic pulmonary angiography (CTPA) is an accurate and safe test for diagnosing PE. The aim of this retrospective analysis was to evaluate the effects on image quality (IQ) of electrocardiogram (ECG) gating during CTPA. METHODS: Fifty consecutive patients presenting for CTPA were included in the study. A single acquisition was performed, resulting in two reconstructions: one at 75% of the R-R interval and the other without ECG influence. IQ evaluation was undertaken by two radiologists, focusing on respiratory and cardiac motion, image noise, low-contrast resolution, vessel and lung clarity, contrast media opacification and artefacts. Various regions of the lungs and vasculature were evaluated, and IQ scores were statistically compared. RESULTS: For the ECG-tagged reconstructions, IQ was noted to be better overall with regard to vessel clarity (P < 0.05) and cardiac motion (P < 0.05), while lung clarity was better only in the left lower zone (P < 0.05). IQ was better with regard to image noise (P < 0.05) and low-contrast resolution (P < 0.05) in the non-ECG-tagged reconstructions. No statistical IQ difference between the two types of reconstruction was noted with regard to respiratory motion, contrast media opacification or presence of artefacts. CONCLUSION: The two types of reconstruction provide complementary information for evaluating CTPA results.

Measurement of vascular calcification using CT fistulograms.

BACKGROUND: Vascular calcification (VC), precipitated by calcium and phosphate imbalance, is a major contributor to cardiovascular disease (CVD) in chronic kidney disease (CKD). Electron-beam computed tomography (EBCT) quantitatively assesses coronary artery calcification (CAC), with VC scores predictive of atherosclerosis and cardiac events in the general and CKD population. EBCT is not readily available but spiral CT can also provide quantitative assessment of the extent of VC. CT fistulograms can be used as initial investigation for arterio-venous fistula (AVF) problems in haemodialysis (HD). The images obtained include thoracic aorta, brachio-cephalic, subclavian and common carotid arteries which allow assessment of the extent of VC in these vessels. No study to date has combined the CT fistulogram with concurrent determination of VC. METHODS: We hypothesize that a single investigation for AVF management may also provide information on VC. We retrospectively analysed CT fistulograms on 28 HD patients determining VC scores (in Hounsfield units) in AVF, subclavian and carotid arteries and aorta. We correlated these scores with patient demographics, serum markers of mineral metabolism (time averaged for the period 6 months prior to CT) and calcium-based phosphate binders. RESULTS: Patients (60.7% male) had a median age of 59 years and 46.4% were diabetic. The mean duration of dialysis was 17.5 months. CT fistulograms showed predominantly aortic (75% of patients) and subclavian (75%) calcifications, with only 21.4% having carotid VC and minimal VC at the level of AVF. Median VC scores were 619.8 (0-1481.4) for aorta and 521.7 (0-1139.6) for subclavian (scores of >400 indicate severe atherosclerotic disease), but there was no significant correlation with serum markers or duration of HD. Increasing age correlated significantly with greater VC in aortic (R = 0.53, P = 0.003) and subclavian (R = 0.40, P = 0.03) vessels, as well as with the number of VC sites involved. CAC was present in most patients (89.3%) but CAC scores were not able to be determined because of cardiac movement. CONCLUSION: Concurrent determination of the degree of calcification in certain vessels may be possible from CT studies assessing AVF structure. VC scores provided by CT fistulograms could contribute to HD patient CVD risk assessment but studies with larger patient numbers are required to determine their relevance.

Cross-strand disulphides in cell entry proteins: poised to act.

Cross-strand disulphides (CSDs) are unusual bonds that link adjacent strands in the same beta-sheet. Their peculiarity relates to the high potential energy stored in these bonds, both as torsional energy in the highly strained disulphide linkage and as deformation energy stored in the sheet itself. CSDs are relatively rare in protein structures but are conspicuous by their presence in proteins that are involved in cell entry. The finding that entry of botulinum neurotoxin and HIV into mammalian cells involves cleavage of CSDs suggests that the activity of other cell entry proteins may likewise involve cleavage of these bonds. We examine emerging evidence of the involvement of these unusual disulphides in cell entry events.