Changing trends in a decade of vascular radiology-the impact of technical developments of non-invasive techniques on vascular imaging

Objectives: This review aims to establish the impact on conventional angiography and endovascular intervention of contrast-enhanced magnetic resonance angiography (CE-MRA) and contrast-enhanced computed tomography angiography (CE-CTA) on a background of evolving technology, changing clinical requirements and resulting clinical repercussions. Methods: The angiographic and interventional caseload was prospectively recorded between 1997 and 2010, along with the CE-MRA and CE-CTA caseload. Waiting times and the marginal cost analyses for 2001 and 2009 were also prospectively established. Results: Conventional diagnostic angiographies declined from a peak of 847 to 121 per year while endovascular interventions continue in similar numbers. CE-MRA increased from effectively none initially to 620 per year while CE-CTA has currently risen to 396 per year. Total diagnostic study numbers have increased but at reduced cost. Various influences are clear, including on-site modality availability, capability and accuracy along with impact of new therapies, research studies and adverse events. Conclusions: Vascular imaging has undergone a metamorphosis in little over a decade because of CE-MRA and CE-CTA. With waiting times significantly reduced since the start of the study and the cost-effectiveness of both CE-MRA and CE-CTA as primary diagnostic investigations established, further development of these services is inevitable

Inter-study reproducibility of arterial spin labelling magnetic resonance imaging for measurement of renal perfusion in healthy volunteers at 3 Tesla

Background: Measurement of renal perfusion is a crucial part of measuring kidney function. Arterial spin labelling magnetic resonance imaging (ASL MRI) is a non-invasive method of measuring renal perfusion using magnetised blood as endogenous contrast. We studied the reproducibility of ASL MRI in normal volunteers.<p></p> Methods: ASL MRI was performed in healthy volunteers on 2 occasions using a 3.0 Tesla MRI scanner with flow-sensitive alternating inversion recovery (FAIR) perfusion preparation with a steady state free precession (True-FISP) pulse sequence. Kidney volume was measured from the scanned images. Routine serum and urine biochemistry were measured prior to MRI scanning.<p></p> Results: 12 volunteers were recruited yielding 24 kidneys, with a mean participant age of 44.1 ± 14.6 years, blood pressure of 136/82 mmHg and chronic kidney disease epidemiology formula estimated glomerular filtration rate (CKD EPI eGFR) of 98.3 ± 15.1 ml/min/1.73 m2. Mean kidney volumes measured using the ellipsoid formula and voxel count method were 123.5 ± 25.5 cm3, and 156.7 ± 28.9 cm3 respectively. Mean kidney perfusion was 229 ± 41 ml/min/100 g and mean cortical perfusion was 327 ± 63 ml/min/100 g, with no significant differences between ASL MRIs. Mean absolute kidney perfusion calculated from kidney volume measured during the scan was 373 ± 71 ml/min. Bland Altman plots were constructed of the cortical and whole kidney perfusion measurements made at ASL MRIs 1 and 2. These showed good agreement between measurements, with a random distribution of means plotted against differences observed. The intra class correlation for cortical perfusion was 0.85, whilst the within subject coefficient of variance was 9.2%. The intra class correlation for whole kidney perfusion was 0.86, whilst the within subject coefficient of variance was 7.1%.<p></p> Conclusions: ASL MRI at 3.0 Tesla provides a repeatable method of measuring renal perfusion in healthy subjects without the need for administration of exogenous compounds. We have established normal values for renal perfusion using ASL MRI in a cohort of healthy volunteers.<p></p&gt

Measurement of the triple-gluon vertex from 4-jet events at LEP

From the combined data of 1990 and 1991 of the DELPHI experiment at LEP, 13057 4-jet events are obtained and used for determining the contribution of the triple-gluon vertex. The relevant variables are the generalized Nachtmann Reiter angle θNR* and the opening angle of the two least energetic jets. A fit to their two-dimensional distribution yields Mathematical expression where CA/CF is the ratio of the coupling strength of the triple-gluon vertex to that of gluon bremsstrahlung from quarks, and NC/NA, the ratio of the number of quark colours to the number of gluons. This constitutes a convincing model-independent proof of the existence of the triple-gluon vertex, since its contribution is directly proportional to CA/CF. The results are in agreement with the values expected from QCD:CA/CF=2.25, and NC/NA=3/8. © 1993 Springer-Verlag