Dual-energy computed tomography in acute ischemic stroke: state-of-the-art.

Dual-energy computed tomography (DECT) allows distinguishing between tissues with similar X-ray attenuation but different atomic numbers. Recent studies demonstrated that this technique has several areas of application in patients with ischemic stroke and a potential impact on patient management. After endovascular stroke therapy (EST), hyperdense areas can represent either hemorrhage or contrast staining due to blood-brain barrier disruption, which can be differentiated reliably by DECT. Further applications are improved visualization of early infarctions, compared to single-energy computed tomography, and prediction of transformation into infarction or hemorrhage in contrast-enhancing areas. In addition, DECT allows detection and evaluation of the material composition of intra-arterial clots after EST. This review summarizes the clinical state-of-the-art of DECT in patients with stroke, and features some prospects for future developments. KEY POINTS: • Dual-energy computed tomography (DECT) allows differentiation between tissues with similar X-ray attenuation but differentatomic numbers. • DECT has several areas of application in patients with ischemic stroke and a potential impact on patient management. • Prospects for future developments in DECT may improve treatment decision-making.

Supernumerary kidneys: a clinical and radiological analysis of nine cases.

BACKGROUND: A supernumerary kidney (SK) is an additional kidney with its own capsule and blood supply that is not fused with the ipsilateral kidney (IK). Because individual case reports indicate a high morbidity rate, the aim of this retrospective study was a detailed analysis of this rare anatomical variant. METHODS: Our systematic imaging-based search for SKs, conducted in the period from 2000 and to 2017, yielded 9 cases in total (5 men, 4 women; mean age: 51.8 ± 22.8 years). RESULTS: The SKs were observed on the right in six and on the left side in three cases. In six subjects (66%) they were located caudal and in three cases (33%) cranial to the ipsilateral kidney. Calculi were found in three (33%) of the renal collecting systems. Five (56%) of the SKs had hydronephrosis grade IV and one SK had recurrent pyelonephritis (11%). Two of the ureters opened into the ipsilateral seminal vesicle (22%). Two (22%) SKs were functional but atrophic. Clinically relevant findings were made in 33% of the IKs: atrophy (n = 2), calculi (n = 1), and reflux with recurrent pyelonephritis (n = 1); another 33% had anatomical anomalies without functional impairment. The correct diagnosis of a SK is possible using CT imaging in all subjects. The prevalence of SK based on CT imaging can be estimated to be 1:26750. CONCLUSIONS: CT is the method of choice for visualizing SKs. The correct diagnosis is crucial in preventing dispensable surgical procedures and for providing optimal patient treatment and outcome.

Improved visualisation of early cerebral infarctions after endovascular stroke therapy using dual-energy computed tomography oedema maps.

OBJECTIVE: The aim was to investigate whether dual-energy computed tomography (DECT) reconstructions optimised for oedema visualisation (oedema map; EM) facilitate an improved detection of early infarctions after endovascular stroke therapy (EST). METHODS: Forty-six patients (21 women; 25 men; mean age: 63 years; range 24-89 years) were included. The brain window (BW), virtual non-contrast (VNC) and modified VNC series based on a three-material decomposition technique optimised for oedema visualisation (EM) were evaluated. Follow-up imaging was used as the standard for comparison. Contralateral side to infarction differences in density (CIDs) were determined. Infarction detectability was assessed by two blinded readers, as well as image noise and contrast using Likert scales. ROC analyses were performed and the respective Youden indices calculated for cut-off analysis. RESULTS: The highest CIDs were found in the EM series (73.3 ± 49.3 HU), compared with the BW (-1.72 ± 13.29 HU) and the VNC (8.30 ± 4.74 HU) series. The EM was found to have the highest infarction detection rates (area under the curve: 0.97 vs. 0.54 and 0.90, p < 0.01) with a cut-off value of < 50.7 HU, despite slightly more pronounced image noise. The location of the infarction did not affect detectability (p > 0.05 each). CONCLUSIONS: The EM series allows higher contrast and better early infarction detection than the VNC or BW series after EST. KEY POINTS: • Dual-energy CT EM allows better early infarction detection than standard brain window. • Dual-energy CT EM series allow better early infarction detection than VNC series. • Dual-energy CT EM are modified VNC based on water content of tissue.

Prediction of infarction development after endovascular stroke therapy with dual-energy computed tomography.

OBJECTIVES: After intraarterial recanalisation (IAR), the haemorrhage and the blood-brain barrier (BBB) disruption can be distinguished using dual-energy computed tomography (DECT). The aim of the present study was to investigate whether future infarction development can be predicted from DECT. METHODS: DECT scans of 20 patients showing 45 BBB disrupted areas after IAR were assessed and compared with follow-up examinations. Receiver operator characteristic (ROC) analyses using densities from the iodine map (IM) and virtual non-contrast (VNC) were performed. RESULTS: Future infarction areas are denser than future non-infarction areas on IM series (23.44 ± 24.86 vs. 5.77 ± 2.77; p < 0.0001) and more hypodense on VNC series (29.71 ± 3.33 vs. 35.33 ± 3.50; p < 0.0001). ROC analyses for the IM series showed an area under the curve (AUC) of 0.99 (cut-off: <9.97 HU; p < 0.05; sensitivity 91.18 %; specificity 100.00 %; accuracy 0.93) for the prediction of future infarctions. The AUC for the prediction of haemorrhagic infarctions was 0.78 (cut-off >17.13 HU; p < 0.05; sensitivity 90.00 %; specificity 62.86 %; accuracy 0.69). The VNC series allowed prediction of infarction volume. CONCLUSIONS: Future infarction development after IAR can be reliably predicted with the IM series. The prediction of haemorrhages and of infarction size is less reliable. KEY POINTS: • The IM series (DECT) can predict future infarction development after IAR. • Later haemorrhages can be predicted using the IM and the BW series. • The volume of definable hypodense areas in VNC correlates with infarction volume.

Prognostic significance of hepatic arterial collaterals in liver transplant recipients with biliary strictures.

BACKGROUND: The aim of this study was to determine the prevalence of hepatic artery stenosis (HAS) and the prognostic implications of hepatic arterial collaterals in liver transplant (LT) recipients with biliary strictures. METHODS: The 105 LT recipients transplanted between 2004 and 2015 at our center had documented biliary strictures. HAS and collaterals were assessed in high-quality imaging of the hepatic artery available from 66 recipients. Clinical, demographic, and biochemical recipient and donor data were retrospectively analyzed and tested for their association with biliary or arterial complications after LT. RESULTS: The prevalence of HAS was 68% (45 of 66) in LT recipients with biliary strictures. Seventy-six percent (37 of 49) of patients with nonanastomotic biliary strictures had HAS. This was significantly higher than in patients with anastomotic stricture, where 47% (8 of 17) of patients had a pathological hepatic arteriogram (P=.039). The location of bile duct strictures was not predictive for outcome. In contrast, arterial collaterals were associated with significantly better patient and graft survival. CONCLUSION: Impaired hepatic arterial perfusion is frequently associated with nonanastomotic strictures, but less closely correlated with anastomotic strictures. On survival analysis, hepatic arterial collaterals have a protective effect.

Measures to Prevent Air Embolism in Transthoracic Biopsy of the Lung.

OBJECTIVE: Systemic air embolism (AE) is a rare but feared complication of transthoracic biopsy with potentially fatal consequences. The aim of the study was to assess the effect of patient positioning during transthoracic biopsy on preventing systemic AE. MATERIALS AND METHODS: We compared a historical control group of 610 patients (group 1) who underwent transthoracic biopsy before the implementation of measures to prevent systemic AE during transthoracic biopsy and a group of 1268 patients (group 2) who underwent biopsy after the measures were implemented. The patients in group 2 were placed in the ipsilateral-dependent position so that the lesion being biopsied was located below the level of the left atrium. RESULTS: The rate of systemic AE was reduced from 3.77% to 0.16% (odds ratio [OR], 0.040; 95% CI, 0.010-0.177; p < 0.001). Logistic regression analyses identified needle penetration depth, prone position of the patient during biopsy, location above the level of the left atrium, needle path through ventilated lung, and intubation anesthesia as independent risk factors for systemic AE (p < 0.05). Propensity score-matched analyses identified the number of biopsy samples obtained as an additional risk factor (p = 0.003). The rate of pneumothorax was reduced from 15.41% in group 1 to 5.99% in group 2 (OR, 0.374; 95% CI, 0.307-0.546; p < 0.001). CONCLUSION: Performing transthoracic biopsy with the patient in an ipsilateral-dependent position so that the lesion is located below the level of the left atrium is an effective measure for preventing systemic AE. Needle path through ventilated lung and intubation anesthesia should be avoided whenever possible.

Prognostic factors in endovascular treated pelvic haemorrhage after blunt trauma.

BACKGROUND: Angioembolization is the method of choice for treating haemorrhage after blunt pelvic trauma. The aim of this study was to determine technical factors related to endovascular procedures which might be related to patient outcome. METHODS: This retrospective study included 112 consecutive patients (40 women and 72 men; mean age 57.2 ± 20.0). RESULTS: There were age peaks at 43 and at 77 years. Patients over 65 years had mainly "low-energy" trauma; younger patients were more likely to have polytraumas. Younger patients were more severely injured and had more surgical interventions, larger haematoma volumes, lower Hb levels and required more transfusions than older patients. Women were older than men, had fewer surgeries and waited longer for an angiography (p < 0.05 each). Logistic regression analyses identified the injury severity score (ISS) as relevant for survival before age, haematoma volume and Hb. Propensity score analyses showed that in addition to the need for transfusions, haemoglobin, and haematoma volume, the length of the coils and the number of microcoils used were relevant (p < 0.05 each). The location of haemorrhage in peripheral parietal arteries (superior and inferior gluteal artery) was an influencing factor for re-angiographies, which were associated with considerably longer hospital stays of more than 40 days. Fewer particles had generally been used in these patients. CONCLUSIONS: The use of too few coils and not using microparticles in angioembolization for pelvic haemorrhage are major influencing factors for the mortality or re-angiography rate. Special attention should be given to thorough peripheral embolization with microcoils, in particular for haemorrhage from the parietal branches of the internal iliac artery.

Correlation between degenerative spine disease and bone marrow density: a retrospective investigation.

BACKGROUND: Spondylosis leads to an overestimation of bone mineral density (BMD) with dual-energy x-ray absorptiometry (DXA) but not with quantitative computed tomography (QCT). The correlation between degenerative changes of the spine and QCT-BMD was therefore investigated for the first time. METHODS: One hundred thirty-four patients (66 female and 68 male) with a mean age of 49.0 ± 14.6 years (range: 19-88 years) who received a CT scan and QCT-BMD measurements of spine and hip were evaluated retrospectively. The occurrence and severity of spondylosis, osteochondrosis, and spondylarthrosis and the height of the vertebral bodies were assessed. RESULTS: A negative correlation was found between spinal BMD and number of spondylophytes (ρ = -0.35; p < 0.01), disc heights (r = -0.33; p < 0.01), number of discal air inclusions (ρ = -0.34; p < 0.01), the number of Schmorl nodules (ρ = -0.25; p < 0.01), the number (ρ = -0.219; p < 0.05) and the degree (ρ = -0.220; p < 0.05) of spondylarthrosis. Spinal and hip BMD correlated moderately, but the latter did not correlate with degenerative changes of the spine. In linear regression models age, osteochondrosis and spondylarthrosis were factors influencing spinal BMD. CONCLUSION: Degenerative spinal changes may be associated with reduced regional spinal mineralization. This knowledge could lead to a modification of treatment of degenerative spine disease with early treatment of osteopenia to prevent secondary fractures.

High-Resolution MRA Cerebrovascular Findings in a Tri-Ethnic Population.

BACKGROUND AND PURPOSE: Incidental findings on brain MRI and variations of the circle of Willis (CoW) are relatively common among the general population. Ethnic differences have been described before, but few studies have explored the prevalence of incidental intracranial cerebrovascular findings and CoW variants in the setting of a single multiethnic cohort. The purpose of this investigation was to describe both incidental cerebrovascular findings and the morphology of the CoW on high-resolution 3T TOF-MRA in a UK tri-ethnic population-based cohort and to present updated prevalence estimates and morphologic reference values. MATERIALS AND METHODS: We studied participants from the UK Southall and Brent REvisited study who underwent 3T brain MRI between 2014 and 2018. TOF-MRA images were assessed for the presence of incidental cerebrovascular findings and used to determine CoW anatomy. RESULTS: Seven hundred fifty participants (mean age, 71.28 [SD, 6.46] years; range, 46-90 years; 337 women), 322 White Europeans, 253 South Asians, and 175 African Caribbeans were included. Incidental cerebrovascular findings were observed in 84 subjects (11.2%, 95% CI, 9.0%-13.7%; 36 women; 42.86%, 95% CI, 32.11%-54.12%), with cerebral aneurysms being the most frequent followed by intracranial arterial stenoses with the highest prevalence among South Asians compared with White European (OR: 2.72; 95% CI, 1.22-6.08; P = .015) and African Caribbean subjects (OR: 2.79; 95% CI, 1.00-7.82; P = .051). Other findings included arteriovenous malformations and infundibula. The CoW was found to be more often complete in women than in men (25.22% compared with 18.41%, P = .024) and in African Caribbean (34.86%) compared with White European (19.19%) and South Asian (14.23%) subjects (P < .001 each). CONCLUSIONS: Intracranial arterial stenoses were independently associated with ethnicity after adjusting for vascular risk factors, having the highest prevalence among South Asians. The prevalence of aneurysms was higher than that in previous population-based studies. We observed anatomic differences in the CoW configuration among women, men, and ethnicities.

Where is VALDO? VAscular Lesions Detection and segmentatiOn challenge at MICCAI 2021.

Imaging markers of cerebral small vessel disease provide valuable information on brain health, but their manual assessment is time-consuming and hampered by substantial intra- and interrater variability. Automated rating may benefit biomedical research, as well as clinical assessment, but diagnostic reliability of existing algorithms is unknown. Here, we present the results of the VAscular Lesions DetectiOn and Segmentation (Where is VALDO?) challenge that was run as a satellite event at the international conference on Medical Image Computing and Computer Aided Intervention (MICCAI) 2021. This challenge aimed to promote the development of methods for automated detection and segmentation of small and sparse imaging markers of cerebral small vessel disease, namely enlarged perivascular spaces (EPVS) (Task 1), cerebral microbleeds (Task 2) and lacunes of presumed vascular origin (Task 3) while leveraging weak and noisy labels. Overall, 12 teams participated in the challenge proposing solutions for one or more tasks (4 for Task 1-EPVS, 9 for Task 2-Microbleeds and 6 for Task 3-Lacunes). Multi-cohort data was used in both training and evaluation. Results showed a large variability in performance both across teams and across tasks, with promising results notably for Task 1-EPVS and Task 2-Microbleeds and not practically useful results yet for Task 3-Lacunes. It also highlighted the performance inconsistency across cases that may deter use at an individual level, while still proving useful at a population level.

Accelerated vascular aging: Ethnic differences in basilar artery length and diameter, and its association with cardiovascular risk factors and cerebral small vessel disease.

Background and aims: Risk of stroke and dementia is markedly higher in people of South Asian and African Caribbean descent than white Europeans in the UK. This is unexplained by cardiovascular risk factors (CVRF). We hypothesized this might indicate accelerated early vascular aging (EVA) and that EVA might account for stronger associations between cerebral large artery characteristics and markers of small vessel disease. Methods: 360 participants in a tri-ethnic population-based study (120 per ethnic group) underwent cerebral and vertebral MRI. Length and median diameter of the basilar artery (BA) were derived from Time of Flight images, while white matter hyperintensities (WMH) volumes were obtained from T1 and FLAIR images. Associations between BA characteristics and CVRF were assessed using multivariable linear regression. Partial correlation coefficients between WMH load and BA characteristics were calculated after adjustment for CVRF and other potential confounders. Results: BA diameter was strongly associated with age in South Asians (+11.3 µm/year 95% CI = [3.05; 19.62]; p = 0.008), with unconvincing relationships in African Caribbeans (3.4 µm/year [-5.26, 12.12]; p = 0.436) or Europeans (2.6 µm/year [-5.75, 10.87]; p = 0.543). BA length was associated with age in South Asians (+0.34 mm/year [0.02; 0.65]; p = 0.037) and African Caribbeans (+0.39 mm/year [0.12; 0.65]; p = 0.005) but not Europeans (+0.08 mm/year [-0.26; 0.41]; p = 0.653). BA diameter (rho = 0.210; p = 0.022) and length (rho = 0.261; p = 0.004) were associated with frontal WMH load in South Asians (persisting after multivariable adjustment for CVRF). Conclusions: Compared with Europeans, the basilar artery undergoes more accelerated EVA in South Asians and in African Caribbeans, albeit to a lesser extent. Such EVA may contribute to the higher burden of CSVD observed in South Asians and excess risk of stroke, vascular cognitive impairment and dementia observed in these ethnic groups.

Immediate Versus Delayed Surgical Treatment of Lumbar Disc Herniation for Acute Motor Deficits: The Impact of Surgical Timing on Functional Outcome.

STUDY DESIGN: A retrospective cohort study. OBJECTIVE: The aim of the study was to assess the impact of time to surgery in patients with motor deficits (MDs) on their functional outcome. The current single-center study presents results of emergency surgery for LDH in a group of patients with acute paresis in a "real-world" setting. SUMMARY OF BACKGROUND DATA: MDs are a frequent symptom of lumbar disc herniation (LDH). Although surgery within 48 hours has been recommended for cauda-equina syndrome, the best timing of surgery for acute MDs continues to be debated. The effect of early surgery has been proposed but remains to be unproven. METHODS: A total of 330 patients with acute paresis caused by LDH acutely referred to our department and surgically treated using microsurgical discectomy from January 2013 to December 2015 were included. Based on the duration of MD and surgical timing, all patients were classified into two categories: Group I included all patients with paresis <48 hours and Group II included all patients with paresis >48 hours. Patient demographics, LDH/clinical/treatment characteristics, and outcomes were collected prospectively.Severity of paresis [Medical Research Council (MRC) Grade 0-4], surgery-related complications, functional recovery of motor/sensory deficits, sciatica, retreatment/recurrence rates, and overall neurological outcome were analyzed. RESULTS: Group I showed significantly faster recovery of moderate/severe paresis (MRC 0-3) at discharge, and 6-weeks/3-months follow up (P ≤ 0.001), whereas there were no significant differences in recovery for mild paresis (MRC 4). Sensory deficits also recovered substantially faster in Group I at 6-weeks (P = 0.003) and 3-months follow up (P = 0.045). Body mass index, preoperative MRC-grade, and duration of MDs were identified as significant predictors for recovery of paresis at all follow ups with substantial impact on patient reported outcomes including sciatica and/or dermatomal sensory deficits. CONCLUSION: Given the superior rates of neurological recovery of acute moderate/severe MDs, immediate surgery should be the primary option. However, a prospective randomized clinical trial is needed to confirm the superiority of emergency surgery. LEVEL OF EVIDENCE: 3.

Safety and Efficacy of Surgical and Endovascular Treatment for Distal Anterior Cerebral Artery Aneurysms: A Systematic Review and Meta-Analysis.

BACKGROUND: Aneurysms of the distal anterior cerebral artery (DACA) are rare, representing between 1% and 9% of all intracranial aneurysms. The best treatment strategy for these aneurysms continues to be debated. OBJECTIVE: We conducted a systematic review of the literature to evaluate the safety and efficacy of treatment strategies of DACA aneurysms. METHODS: A systematic search of Medline, Embase, Scopus, and Web of Science was performed for studies published from January 2000 to August 2015. We included studies describing treatment of DACA aneurysms with ≥10 patients. Random effects meta-analysis was used to pool the following outcomes: complete occlusion, technical success, periprocedural morbidity/mortality and stroke rates, aneurysm recurrence/rebleed, and long-term neurologic morbidity/mortality. RESULTS: Thirty studies with 1329 DACA aneurysms were included. Complete occlusion was 95% (95% confidence interval [CI], 91.0%-97.0%) in the surgical group and 68% (95% CI, 56.0%-78.0%) in the endovascular group (P < 0.0001). Aneurysm recurrence occurred in 3% (95% CI, 2.0%-4.0%) after surgery and in 19.1% (95% CI, 12.0%-27.0%) after endovascular treatment (P < 0.0001). Overall neurologic morbidity and mortality were 15% (95% CI, 11.0%-21.0%) and 9% (95% CI, 7.0%-11.0%) after surgery and 14% (95% CI, 10.0%-19.0%) (P = 0.725) and 7% (95% CI, 5.0%-10.0%) (P = 0.422) after endovascular treatment, respectively. Overall long-term favorable neurologic outcome was 80% and it was equal in both groups (80%; 95% CI, 73.0%-85.0% in the surgical group and 80%; 95% CI, 72.0%-87.0% in the endovascular group) (P = 0.892). CONCLUSIONS: Our meta-analysis showed that both treatment modalities are technically feasible and effective with sufficient long-term aneurysm occlusion and acceptable recurrence/rebleed rates. Surgical treatment is associated with superior angiographic outcomes. There were no substantial differences in procedure-related morbidity and mortality. These findings are important because they suggest that therapy of DACA aneurysms should be performed on a selective, case-by-case basis to maximize patient benefits.

Iatrogenic Cardiac Tamponade During Endovascular Aortic and Mesenteric Stent Grafting: A Case Report.

The authors report a case of left ventricular perforation and cardiac tamponade in a patient undergoing endovascular aortic and mesenteric stent grafting. During the procedure, the anesthetist noticed a sudden increase in central venous pressure and a decrease in blood pressure. Cardiac tamponade was suspected and confirmed by transesophageal echocardiography. Pericardiotomy resulted only in temporary stabilization. Emergency sternotomy revealed left ventricular perforation. Both anesthetists and radiologists have to be aware of such rare but severe complications of interventional procedures.

Systemic air embolism causing acute stroke and myocardial infarction after percutaneous transthoracic lung biopsy - a case report.

The air embolism in this case was likely to have been caused by positioning the patient in a prone position, which was associated with the lesion to be biopsied being at a maximum height over the left atrium. Due to the resulting negative pressure, air entered through a fistula that formed between the airspace and the pulmonary vein. The air could have been trapped in the left atrium by positioning the patient in left lateral position. The event itself could have been prevented by positioning the patient in an ipsilateral dependent position during the biopsy. In addition to hyperbaric oxygen therapy, the preferred treatment options are positioning maneuvers, administration of pure oxygen, and heparinization.

Factors influencing intracranial vessel densities on unenhanced computed tomography: differences between hemispheres.

The aim was to identify the factors influencing intracranial vessel density (VD). The Hounsfield units of the dense vessel and the contralateral side were measured in 34 patients with arterial clots, 20 with venous clots, and 196 without clots and correlated with skull thickness, density and dimensions, gender, age, red blood cell count (RBC), hemoglobin (HB), hematocrit (HT), creatinine, and sodium. Positive correlations were found between VD and HT, RBC, HB, creatinine, and occipital bone density. Density differences between the right and left intracranial vessels were more accurate (sensitivity/specificity/accuracy=0.91/0.93/0.93 and 0.75/0.87/0.85, respectively) for detecting clots than VD alone. HT, RBC, and HB are the main factors that correlate with VD.

Retrospective morphometric study of the suitability of renal arteries for renal denervation according to the Symplicity HTN2 trial criteria.

OBJECTIVE: The aim of this study was to describe the renal arteries of humans in vivo, as precisely as possible, and to formulate an expected value for the exclusion of renal denervation due to the anatomical situation based on the criteria of the Symplicity HTN trials. DESIGN AND SETTING: In a retrospective cohort study, the renal arteries of 126 patients (57 women, 69 men, mean age 60 ± 17.2 years (CI 57.7 to 63.6)) were segmented semiautomatically from high-contrast CT angiographies. RESULTS: Among the 300 renal arteries, there were three arteries with fibromuscular dysplasia and one with ostial renal artery stenosis. The first left renal artery was shorter than the right (34 ± 11.4 mm (CI 32 to 36) vs 45.9 ± 15 mm (CI 43.2 to 48.6); p<0.0001), but had a slightly larger diameter (5.2 ± 1.4 mm (CI 4.9 to 5.4) vs 4.9 ± 1.2 mm (CI 4.6 to 5.1); p>0.05). The first left renal arteries were 1.1 ± 0.4 mm (CI 0.9 to 1.3), and the first right renal arteries were 0.3 ± 0.6 mm (CI 0.1 to 0.5) thinner in women than in men (p<0.05). Ostial funnels were up to 14 mm long. The cross-sections were elliptical, more pronounced on the right side (p<0.05). In 23 cases (18.3%), the main artery was shorter than 2 cm; in 43 cases (34.1%), the diameter was not >4 mm. Some 46% of the patients, or 58.7% when variants and diseases were taken into consideration, were theoretically not suitable for denervation. CONCLUSIONS: Based on these precise measurements, the anatomical situation as a reason for ruling out denervation appears to be significantly more common than previously suspected. Since this can be the cause of the failure of treatment in some cases, further development of catheters or direct percutaneous approaches may improve success rates.

Retrospective angiographic study to determine the effect of atherosclerotic stenoses of upstream arteries on the degree of atherosclerosis in distal vascular territories.

OBJECTIVE: Experimental coarctation of the aorta prevents the development of downstream atherosclerosis. The aim of this study was to find out whether or not atherosclerotic stenoses protect distal vascular territories from developing atherosclerosis in humans. DESIGN AND SETTING: A total of 2125 vascular segments from angiographies of 101 patients were evaluated by calculating the maximum degree of stenosis (NASCET criteria), the degree of calcification, the degree of collaterals and the Friesinger score. RESULTS: Stenosis ≥30-49% was found in 685 vascular segments (32.2%), ≥50-69% in 490 (23.1%), ≥70-89% in 373 (17.6%) and ≥90% in 265 (12.5%). If a stenosis of at least ≥70-89% was present in the common iliac, the external iliac or the common femoral artery, the degrees of stenosis distal to it were lower than those on the contralateral side (19.8±22.3% (CI 11.7 to 28.0) vs 25.2±20.7% (CI 21.2 to 29.1); Friesinger scores 1.1±1.2 (CI 0.6 to 1.5) vs 1.4±1.1 (CI 1.2 to 1.6); degrees of calcification 0.8±1.0 (CI 0.4 to 1.1) vs 1.2±1.1 (CI 1.2 to 1.6); p<0.05 each). This effect depended on the degree of proximal stenosis, but not on collaterals, and was most pronounced distal to stenoses of the common iliac, the superficial femoral and the popliteal artery. In regression models, stenoses of the pelvic arteries were shown to be an independent protective factor for the distal vascular territories. CONCLUSIONS: Atherosclerotic stenoses seem to protect distal vascular territories from developing atherosclerosis. The underlying pathophysiological mechanism of this phenomenon remains to be determined. It could be based on pulse pressure reduction.