A 78 Seconds Complete Brain MRI Examination in Ischemic Stroke: A Prospective Cohort Study

BACKGROUND

Fast 78-second multicontrast echo-planar MRI (EPIMix) has shown good diagnostic performance for detecting infarctions at a comprehensive stroke center, but its diagnostic performance has not been evaluated in a prospective study at a primary stroke center.

PURPOSE

To prospectively determine whether EPIMix was noninferior in detecting ischemic lesions compared to routine clinical MRI.

STUDY TYPE

Prospective cohort study.

POPULATION

A total of 118 patients with acute MRI and symptoms of ischemic stroke.

FIELD STRENGTH AND SEQUENCE

A 3 T. EPIMix (echo-planar based: T1-FLAIR, T2-weighted, T2-FLAIR, T2*, DWI) and routine clinical MRI sequences (T1-weighted fast spin echo, T2-weighted PROPELLER, T2-weighted-FLAIR fast spin echo, T2* gradient echo echo-planar, and DWI spin echo echo-planar).

ASSESSMENT

Three radiologists, blinded for clinical information, assessed signs of ischemic lesions (DWI↑, ADC↓, and T2/T2-FLAIR↑) on EPIMix and routine clinical MRI, with disagreements solved in consensus with a fourth reader to establish the reference standard.

STATISTICAL TESTS

Diagnostic performance including sensitivity and specificity against the reference standard was evaluated. EPIMix sensitivity was tested for noninferiority compared to the reference standard using Nam's restricted maximum likelihood estimation (RMLE) Score. A P-value < 0.05 was considered statistically significant.

RESULTS

Of 118 patients (mean age 62 ± 16 years, 58% males), 25% (n = 30) had MRI signs of acute infarcts. EPIMix was noninferior with 97% (95% CI 83-100) sensitivity for reader 1, 100% (95% CI 88-100) sensitivity for reader 2, and 90% (95% CI 88-98) sensitivity for reader 3 vs. 93% (95% CI 78-99) sensitivity for readers 1 and 2 and 90% (95% CI 74-98) for reader 3 on routine clinical MRI. Specificity was 99% (95% CI 94-100) for reader 1, 100% (95% CI 96-100) for reader 2, and 98% (95% CI 92-100) for reader 3 on EPIMix vs. 100% (95% CI 96-100) for all readers on routine clinical MRI.

CONCLUSION

EPIMix was noninferior to routine clinical MRI for the diagnosis of acute ischemic stroke.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 2.

Red blood cell storage duration and long-term mortality in patients undergoing cardiac intervention: a Danish register study

OBJECTIVES

To study the effect of red blood cell (RBC) storage duration on long-term mortality in patients undergoing cardiac intervention.

BACKGROUND

RBCs undergo numerous structural and functional changes during storage. Observational studies have assessed the association between RBC storage duration and patient outcomes with conflicting results.

METHODS

Between January 2006 and December 2014, 82 408 patients underwent coronary angiography. Of these, 1856 patients received one to four RBC units within 30 days after this procedure. Patients were allocated according to length of RBC storage duration: short-term (≤11 days), intermediate (IM)-term (12-23 days) and long-term (≥24 days). The study endpoints were 30-day and long-term all-cause mortality.

RESULTS

A total of 4168 RBC units were given to 1856 patients. The mean RBC storage duration was 8.5 ± 2.1, 17.7 ± 3.4 and 29.9 ± 3.4 days in the short-term, IM-term and long-term storage groups, respectively. There was no difference in baseline characteristics between the groups. The long-term storage group received significantly more units (2.4 ± 1.0 units) as compared to the short-term (2.0 ± 1.0 units; P < 0.001) and IM-term storage group (2.2 ± 1.0 units; P < 0.01). In the survival analysis, there was no significant difference in all-cause mortality between the groups (log-rank: 0.509 for 30-days mortality; 0.493 for 5-year mortality). Additional stratified analysis demonstrated no association between RBC storage duration and long-term mortality.

CONCLUSION

This study did not find an association between RBC storage duration and 30-days or long-term mortality in patients undergoing cardiac intervention.

Guidelines for the use of magnetic resonance imaging in diagnosing and monitoring the treatment of multiple sclerosis: recommendations of the Swedish Multiple Sclerosis Association and the Swedish Neuroradiological Society

Multiple sclerosis (MS) is associated with inflammatory lesions in the brain and spinal cord. The detection of such inflammatory lesions using magnetic resonance imaging (MRI) is important in the consideration of the diagnosis and differential diagnoses of MS, as well as in the monitoring of disease activity and predicting treatment efficacy. Although there is strong evidence supporting the use of MRI for both the diagnosis and monitoring of disease activity, there is a lack of evidence regarding which MRI protocols to use, the frequency of examinations, and in what clinical situations to consider MRI examination. A national workshop to discuss these issues was held in Stockholm, Sweden, in August 2015, which resulted in a Swedish consensus statement regarding the use of MRI in the care of individuals with MS. The aim of this consensus statement is to provide practical advice for the use of MRI in this setting. The recommendations are based on a review of relevant literature and the clinical experience of workshop attendees. It is our hope that these recommendations will benefit individuals with MS and guide healthcare professionals responsible for their care.

Amputation-Free Survival after Crural Percutaneous Transluminal Angioplasty for Critical Limb Ischemia

Background and Aim:

To evaluate the amputation-free survival after below the knee percutaneous transluminal angioplasty in a consecutive group of patients with critical ischemia of the lower extremity.

Materials and Methods:

A total of 70 consecutive patients with critical ischemia were treated with below the knee percutaneous transluminal angioplasty at the vascular center at Rigshospitalet with the purpose of limb salvage. All patients were deemed unfit for major surgery due to anatomical limitations or severe co-morbidity, and no prior attempts of revascularization were performed. Follow-up clinical examinations were performed within 6 weeks and after 1 year. All medical records were crosschecked with the national vascular registry ensuring a valid 1-year status in 97% of the patients.

Results:

A total of 15 major amputations were performed during follow-up, with 11 amputations performed within the first year. Complications after percutaneous transluminal angioplasty were rare. Cumulative mortality after 1 and 2 years was 22% and 34%, respectively. Amputation-free survival at 1 and 2 years of follow-up was 68% and 58%, respectively. There were no association between known risk factors such as diabetes, ischemic ulcers, cardiac disease, history of smoking, major amputation, or overall amputation.

Conclusion:

Below the knee percutaneous transluminal angioplasty in patients with end-stage peripheral arterial disease and critical limb ischemia is a safe procedure in relieving critical ischemia, reducing the short-term rate of a major amputation as opposed to best medical treatment alone.

Three-dimensional ultrasound evaluation of small asymptomatic abdominal aortic aneurysms

OBJECTIVE

Non-invasive and reproducible size measurements that correlate well with computed tomography (CT) are desirable in the management of small abdominal aortic aneurysms (AAA). Three dimensional ultrasound (3D-US) technology may reduce inaccuracy because of variations in orientation of the image planes and axis. This study aimed to determine any differences in paired size estimation associated with three 3D-US derived methods using 3D-CT as the gold standard. When CTA was not available, the patients were enrolled anyway to assess 3D-US reproducibility in terms of agreement between two physicians.

METHODS

In the period from 1 March 2013 to 27 February 2014, consecutive patients with a small AAA, <5.5 cm for men and <5.2 cm for women, underwent 3D-US examination and three AAA size measures were obtained: dual plane diameter, diameter perpendicular to the residual sac's centreline and a partial volume.

RESULT

In all, 122 consecutive US examinations were performed. Patients were excluded because of inadequate AAA size (n = 11) and for technical reasons (n = 11). Thus, 100 patients (F/M; 20/80) with a median maximum AAA diameter of 46 (range 31-55) mm were analysed. The mean US dual plane diameter and the 3D-US centreline diameter were 2.6 mm and 1.8 mm smaller than the mean 3D-CT centreline diameter, respectively (p = .003). The inter-observer reproducibility coefficient was 3.7 mm for the US dual plane diameter and 3.2 mm for the 3D-US centreline diameter (p = 0.222). For the partial volume, the reproducibility was 8-12%, corresponding to a diameter variability of ±3 mm. The median time used for post-processing of the 3D-US acquisition was 72 (range 46-108) seconds per examination.

CONCLUSION

3D-US demonstrated an acceptable reproducibility and a good agreement with 3D-CT, and has the potential to improve future AAA management through more reliable ultrasound guided size estimates.

Endovascular repair of acute uncomplicated aortic type B dissection promotes aortic remodelling: 1 year results of the ADSORB trial

OBJECTIVES

Uncomplicated acute type B aortic dissection (AD) treated conservatively has a 10% 30-day mortality and up to 25% need intervention within 4 years. In complicated AD, stent grafts have been encouraging. The aim of the present prospective randomised trial was to compare best medical treatment (BMT) with BMT and Gore TAG stent graft in patients with uncomplicated AD. The primary endpoint was a combination of incomplete/no false lumen thrombosis, aortic dilatation, or aortic rupture at 1 year.

METHODS

The AD history had to be less than 14 days, and exclusion criteria were rupture, impending rupture, malperfusion. Of the 61 patients randomised, 80% were DeBakey type IIIB.

RESULTS

Thirty-one patients were randomised to the BMT group and 30 to the BMT+TAG group. Mean age was 63 years for both groups. The left subclavian artery was completely covered in 47% and in part in 17% of the cases. During the first 30 days, no deaths occurred in either group, but there were three crossovers from the BMT to the BMT+TAG group, all due to progression of disease within 1 week. There were two withdrawals from the BMT+TAG group. At the 1-year follow up there had been another two failures in the BMT group: one malperfusion and one aneurysm formation (p = .056 for all). One death occurred in the BMT+TAG group. For the overall endpoint BMT+TAG was significantly different from BMT only (p < .001). Incomplete false lumen thrombosis, was found in 13 (43%) of the TAG+BMT group and 30 (97%) of the BMT group (p < .001). The false lumen reduced in size in the BMT+TAG group (p < .001) whereas in the BMT group it increased. The true lumen increased in the BMT+TAG (p < .001) whereas in the BMT group it remained unchanged. The overall transverse diameter was the same at the beginning and after 1 year in the BMT group (42.1 mm), but in the BMT+TAG it decreased (38.8 mm; p = .062).

CONCLUSIONS

Uncomplicated AD can be safely treated with the Gore TAG device. Remodelling with thrombosis of the false lumen and reduction of its diameter is induced by the stent graft, but long term results are needed.

Cortisol metabolism after weight loss: associations with 11 β-HSD type 1 and markers of obesity in women

OBJECTIVE

Increased glucocorticoid metabolite excretion and enhanced expression and activity of 11β-hydroxysteroid dehydrogenase type 1 in adipose tissue are closely correlated with obesity and its detrimental consequences. Weight loss ameliorates the latter. The aim of this study was to explore whether increased glucocorticoid exposure in obesity is improved with substantial weight loss and thus is a consequence rather than a cause of obesity.

DESIGN AND PATIENTS

A prospective cohort study in 31 women.

MEASUREMENTS

11β-HSD type 1 expression and activity, urinary glucocorticoid metabolite excretion, body composition including regional adipose tissue depots and insulin resistance by HOMA-IR before and 2 years after gastric bypass surgery.

RESULTS

After weight loss, excretion of cortisol and cortisone metabolites decreased. Both cortisol and cortisone metabolite excretion correlated with central obesity, where the intraabdominal fat depot showed the strongest association. Cortisol metabolites correlated with 11β-HSD type 1 activity in abdominal subcutaneous adipose tissue. The ratio of cortisol to cortisone metabolites [(5α-tetrahydrocortisol (5αTHF) + tetrahydrocortisol (THF) + α-cortol)/(tetrahydrocortisone (THE) + α-cortolone)] and the ratio of 5α-THF/THF both decreased after stable weight loss, reflecting a downregulation of the net activities of 11β-HSD type 1 and 5α-reductase.

CONCLUSION

Long-term weight loss in women is not only followed by reduced glucocorticoid production, but also favourably decreases the global and tissue-specific activity of the cortisol-activating enzyme 11 β-HSD type 1, possibly contributing to the health benefits of bariatric surgery.

Celiac trunk coverage in endovascular aneurysm repair

BACKGROUND AND AIMS

This retrospective study was undertaken to examine the risks associated with obstruction of the coeliac trunk in the process of treating aneurysms with endografting.

MATERIAL AND METHODS

120 patients were treated by endografting for aneurysmal disease. Of these, a subgroup of 9 patients had their celiac trunk covered. If possible, a preoperative angiography was performed to evaluate collateral flow from the superior mesenteric artery. This was considered to predict the risk for ischemia.

RESULTS

None of the patients had any severe clinical event of the celiac trunk occlusion or clinical signs of intestinal ischemia. Three patients had transient increase of liver enzymes.

CONCLUSIONS

In cases where the distal landing zone of the descending thoracic aorta is to short for endografting, covering of the celiac trunk may be an option if no other surgical alter-native is apparent. Preoperative angiography to visualise the presence of collateral vessels from the superior mesenteric artery is recommended.

New interpretation of arterial stiffening due to cigarette smoking using a structurally motivated constitutive model

Cigarette smoking is the leading self-inflicted risk factor for cardiovascular diseases; it causes arterial stiffening with serious sequelea including atherosclerosis and abdominal aortic aneurysms. This work presents a new interpretation of arterial stiffening caused by smoking based on data published for rat pulmonary arteries. A structurally motivated "four fiber family" constitutive relation was used to fit the available biaxial data and associated best-fit values of material parameters were estimated using multivariate nonlinear regression. Results suggested that arterial stiffening caused by smoking was reflected by consistent increase in an elastin-associated parameter and moreover by marked increase in the collagen-associated parameters. That is, we suggest that arterial stiffening due to cigarette smoking appears to be isotropic, which may allow simpler phenomenological models to capture these effects using a single stiffening parameter similar to the approach in isotropic continuum damage mechanics. There is a pressing need, however, for more detailed histological information coupled with more complete biaxial mechanical data for a broader range of systemic arteries.

Incidence of systemic inflammatory response syndrome after endovascular aortic repair

AIM

The aim of this study was to estimate the incidence of the post-implantation syndrome/systemic inflammatory response syndrome (SIRS) after endovascular aortic repair.

METHODS

All patients, undergoing elective primary endovascular repair of an asymptomatic infrarenal abdominal aortic aneurysm during 2007, were retrospectively evaluated for SIRS within the first 5 postoperative days. The only exclusion-criteria were missing data. SIRS was assessed using the criteria defined by the American College of Chest Physicians and Society of Critical Care Medicine Consensus Conference Committee.

RESULTS

Sixty-six patients were included, 40 (60%) met the SIRS criteria within the first 5 postoperative days (95% of the 40 patients met the criteria within 3 days). We found no significant differences between the SIRS and the non-SIRS group in baseline characteristics or other data including volume of the contrast media used, type of groin access, adjunctive procedures and duration of surgery. In total, 11 (28%) patients in the SIRS group and 4 (15%) patients in the non-SIRS group underwent re-interventions. Median follow-up period was 26 (range 20-32) months. Thirty-day mortality did not differ in the groups (3% in the SIRS group vs. none in the non-SIRS group).

CONCLUSION

The high incidence of SIRS after EVAR is unexpected considering the minimally invasive procedure. Further studies on the cause of this response and measures to attenuate the response seem appropriate.

From puncture to closure of the common femoral artery in endovascular aortic repair

In all fields of surgery there is a trend towards less invasive procedures reducing hospital stay, complications and mortality. Open surgery in the treatment of aortic diseases is gradually less applied, and instead endovascular aortic repair - EVAR - is a widely accepted treatment modality of today. The traditional approach in EVAR involves surgical exposure of the femoral arteries with bilateral groin incisions. Through the groin access, and under fluoroscopy, a special insertion sheath introducer is used to position a stent graft in the desired location with the patient in general or epidural anesthesia. The evolving stent-technology with smaller sheath sizes has broadened the scenario for alternative approaches for access and closure of the common femoral arteries. The following review presents an introduction on technical aspects of puncture of the femoral artery and closure of the arterial wall using percutaneous closure devices. We also aim to discuss three important approaches to expose and close the femoral arteries during endovascular aortic repair: The cut down approach, the true percutaneous technique, and the femoral fascial closure. Finally, factors important in the choice of techniques will be discussed in relation to early and late complications. We suggest that a percutaneous femoral approach should initially be considered for all endovascular aortic procedures, but with a low threshold to convert to traditional cut-down technique when complications such as bleeding, stenosis, ischemia, or femoral artery injury occur. The choice of the optimal femoral approach depends on the unique anatomy of each patient.

TEVAR and covering the celiac artery. Is it safe or not?

Thoracic endovascular aortic repair (TEVAR) is the treatment of choice for descending thoracic aortic aneurysms (TAA). However, not all patients with TAA can be treated with the endovascular technique. Insufficient proximal and/or distal sealing zone is the most common reason for open surgery in these patients. If the distal sealing zone above the celiac axis is too short, several endovascular alternatives are possible; hybrid procedures with TEVAR and open by-pass to the celiac artery, custom made stent-grafts with scallop or fenestration for the celiac artery, or intentional coverage of the celiac artery. In the latter case, adequate collateral supply to the upper gastrointestinal tract is crucial. Collateral arteries joining the celiac and the superior mesenteric arteries are well characterized in patients with chronic celiac stenosis or occlusion. Are these collateral pathways sufficient also for sudden iatrogenic closure of the celiac artery? By performing a preoperative angiography of the superior mesenteric artery with temporary balloon occlusion of the celiac artery, collateral capacity between the two vessels can be tested in advance. Exact positioning of the distal end of a large thoracic stent-graft can be challenging and require special considerations and techniques. Most case series in the literature support the efficacy and the safety of intentional celiac covering. However, there are also reports of ischemic foregut complications that could be associated to the procedure. Taken together, in the large majority of patients, it appears that intentional celiac coverage can be done safely provided that sufficient collateral function have been demonstrated in advance.

Endovascular aneurysm repair: state-of-art imaging techniques for preoperative planning and surveillance

Endovascular aneurysm repair (EVAR) represents one of the greatest advances in vascular surgery over the past 50 years. In contrast to conventional aneurysm repair, EVAR requires accurate preoperative imaging and stringent postoperative surveillance. Duplex ultrasound (DUS), transesophageal echocardiography, intravascular ultrasound, computed tomography (CT) and magnetic resonance (MR), each provide useful information for patient selection, choice of endograft type and surveillance. Today most interventionists and surgeons will rely on CT or MR to assess aortic morphology, evaluate access artery patency and locate side branch orifices. However, recent developments in cross-sectional imaging, including advanced image postprocessing, multi-modality image fusion and new contrast agents have resulted in improved spatial resolution for preoperative planning. Advanced reconstruction algorithms, like dynamic CTA and MRA, provide valuable information on dynamic changes in aneurysm morphology that might have an important impact on endograft selection. During follow-up, imaging of the graft and aneurysm is of utmost importance to identify patients in need of secondary intervention. This has led to rigorous follow-up protocols including duplex ultrasound and regular CT examinations. The use of these intense follow-up protocols has recently been questioned because of high radiation dose and the frequent use of nephrotoxic contrast agents. New imaging modalities like contrast enhanced DUS, dynamic MR and dual-source CT could reduce radiation dose and obviate the need for nephrotoxic contrast. Up-to-date knowledge of non-invasive vascular imaging and image processing is crucial for EVAR planning and is essential for the development of follow-up programs involving reduced risk of harmful side effects.

Fluid therapy in acute myocardial infarction: evaluation of predictors of volume responsiveness

BACKGROUND

Static vascular filling pressures suffer from poor predictive power in identifying the volume-responsive heart. The use of dynamic arterial pressure variables, including pulse pressure variation (PPV) has instead been suggested to guide volume therapy. The aim of the present study was to evaluate the performance of several clinically applicable haemodynamic parameters to predict volume responsiveness in a pig closed chest model of acute left ventricular myocardial infarction.

METHODS

Fifteen anaesthetized, mechanically ventilated pigs were studied following acute left myocardial infarction by temporary coronary occlusion. Animals were instrumented to monitor central venous (CVP) and pulmonary artery occlusion (PAOP) pressures and arterial systolic variations (SPV) and PPV. Cardiac output (CO) was measured using the pulmonary artery catheter and by using the PiCCO monitor also giving stroke volume variation (SVV). Variations in the velocity time integral by pulsed-wave Doppler echocardiography were determined in the left (DeltaVTI(LV)) and right (DeltaVTI(RV)) ventricular outflow tracts. Consecutive boluses of 4 ml/kg hydroxyethyl starch were administered and volume responsiveness was defined as a 10% increase in CO.

RESULTS

Receiver-operator characteristics (ROC) demonstrated the largest area under the curve for DeltaVTI(RV) [0.81 (0.70-0.93)] followed by PPV [0.76 (0.64-0.88)] [mean (and 95% CI)]. SPV, DeltaVTI(LV) and SVV did not change significantly during volume loading. CVP and PAOP increased but did not demonstrate significant ROC.

CONCLUSION

PPV may be used to predict the response to volume administration in the setting of acute left ventricular myocardial infarction.

The use of virtual reality for training in carotid artery stenting: a construct validation study

BACKGROUND

Given that carotid artery stenosis (CAS) intervention is procedurally difficult, possesses an extensive learning curve, and involves a grave list of potential complications, construct validation of new non-clinical training devices is of increasing importance.

PURPOSE

To evaluate the construct validity of the Procedicus-Virtual Interventional Simulator Trainer (Procedicus-VIST) and its use as a training tool.

MATERIAL AND METHODS

Sixteen interventionalists (15 males, one female; mean interventional radiology [IR] experience >11 years) and 16 medical students (15 males, one female; no IR experience) received 1 hour of didactic instruction followed by an hour of familiarization training. Subjects then attempted to complete a carotid artery stenting procedure within 1 hour while their performance metrics were recorded. All participants completed a qualitative exit survey of subjective parameters using a visual analog scale.

RESULTS

Procedure and fluoroscopic time was 8.7 and 8.7 min greater in the novice group (P=0.0066 and P=0.0031), respectively. There were no significant differences in performances between the two groups in the remaining metrics of cine loops (number recorded), tool/vessel ratio, coverage percentage, and placement accuracy or residual stenosis. Contrast measurement metrics were found to be too imprecise for statistical analysis. Experienced and novice opinions differed significantly for six of 10 subjective parameters. No statistically significant difference in video-gaming habits was demonstrated.

CONCLUSION

With the exception of the metrics of performance time and fluoroscopic use, construct validity of the Procedicus-VIST carotid metrics were not confirmed. Virtual reality simulation as a training method was valued more by novices than by experienced interventionalists.

Observations on the Failure of Stent-grafts in the Aortic Arch

INTRODUCTION

The results of endovascular stent-grafts in the abdominal aorta and descending thoracic aorta have been encouraging. Expanding the use of thoracic stent-grafts in to the aortic arch has been associated with increasing numbers of complications. Recently isolated cases of stent-graft collapse have been reported.

METHODS

This was a multi-centre European case series. Data was collected retrospectively on seven patients from five experienced endovascular centres with thoracic stent-graft collapse.

RESULTS

Of the seven patients four were treated for traumatic aortic rupture. Six were male, median age 33 (range 17-54) years. During the ensuing 2 months all patients suffered stent-graft collapse. This was symptomatic in 3 patients and the rest were identified on CT. Endovascular management was possible in 6/7 patients using either a balloon expandable stent (n=6) or further stent-graft (n=1). Two patients had persistent type I endoleak despite treatment. Two of the 7 patients died, both of which presented with symptomatic thoracic stent-graft occlusion. Both deaths were a direct result of stent-graft collapse.

CONCLUSIONS

Thoracic stent-graft collapse may be asymptomatic underscoring the importance of stent-graft surveillance. Endovascular management of collapse is possible in most cases using a large balloon expandable stent. Symptomatic collapse is associated with high morbidity and mortality.

Remodeling of the thoracic aorta after stent grafting of type B dissection: a Swedish multicenter study

AIM

Endovascular repair of complicated type B dissections has evolved as a promising alternative to open repair. Previous studies have indicated that continued false lumen flow is a predictor of continued aortic dilatation and risk of rupture during follow-up. This multicenter study was conducted to analyze the postoperative changes of the false lumen after endografting of complicated type B dissections.

METHODS

All patients treated with endovascular stent grafts for thoracic type B dissections at 5 major Vascular Centers in Sweden were identified through local databases. Review of charts and all available pre- and postoperative CT scans were performed to identify demographics, indications for repair as well as postoperative changes of the aorta and false lumen.

RESULTS

A total of 129 patients treated for type B dissections between 1994 and December 2005 were identified. Median radiological follow-up was 14 months. Fourteen patients died perioperatively leaving 115 patients available for analysis. Seventy-four of these had CT imaging of sufficient quality for morphological analysis. The vast majority of acute patients were treated for rupture or end-organ ischemia whereas most chronic patients were treated for asymptomatic aneurysms. In 80% of patients, the false lumen thrombosed along the stent graft but it remained perfused distal to the stent graft fixation in 50% of patients. Only 5% of patients presented with aortic enlargement of the stent grafted area when adequate proximal sealing was achieved. The distal, uncovered aorta displayed expansion in 16% of patients.

CONCLUSIONS

The stent grafted thoracic aorta after type B dissection appears to be stabilized by covering the primary entry site with a stent graft in the majority of both acute and chronic dissections. The uncovered portion of the aorta distal to the stent graft, however, remains at risk of continuous dilatation. Stent grafting for complicated type B thoracic dissections seems to be a treatment option with reasonable morbidity and mortality even though the incidence of severe complications is still significant.

Early alterations in the postprandial VLDL1 apoB-100 and apoB-48 metabolism in men with strong heredity for type 2 diabetes

OBJECTIVES

To study the postprandial triglyceride-rich lipoprotein (TRL) metabolism, specifically the concentrations of very low-density lipoproteins (VLDL); from intestine (apoB-48) and liver (apoB-100), in men with normal fasting triglycerides but at increased risk of developing type 2 diabetes.

DESIGN

Cross-sectional study.

SUBJECTS AND SETTINGS

Sixteen healthy men with at least two first-degree relatives with type 2 diabetes were individually matched with 16 control subjects without known diabetes heredity for: age, body mass index, and fasting triglyceride level. They underwent an 8-h meal tolerance test (919 kcal, 51 g fat) during which lipoproteins were separated by density gradient ultracentrifugation. They were characterized by euglycaemic hyperinsulinaemic clamp, peak VO2, 7-day diet registration and computed tomography.

RESULTS

The relatives were, as expected, more insulin resistant than the controls and had increased concentration of postprandial VLDL1 particles (49% higher for VLDL1 apoB-48, P = 0.04 and 21% higher for VLDL1 apoB-100, P = 0.048). The elevation was related to insulin sensitivity, but not to lifestyle and body composition. Moreover, the concentration of postprandial triglycerides in VLDL1 fraction was inversely related to low-density lipoprotein (LDL) size in both relatives (rs = -0.60, P = 0.03) and controls (rs = -0.72, P = 0.004). There were no differences in the concentration of triglycerides or apoB-48 and apoB-100 particles in the other fractions (plasma, chylomicron or VLDL2).

CONCLUSION

Increased postprandial concentration of TRLs in the VLDL1 fraction seems to be present at an early stage in the development of diabetes and probably contributes to the excess risk of future coronary events in insulin-resistant men.

Treatment of descending thoracic aneurysms by endovascular stent grafting

PURPOSE

Endovascular stent-graft treatment for true aneurysms of the descending thoracic aorta is a valid and effective alternative to conventional surgery. A review of our experience with 21 consecutive patients is reported and technical considerations are discussed.

METHODS

Twenty-one patients (mean age 73 years) with true aneurysms of the descending thoracic aorta (n = 14) or contained rupture (n = 7) were treated between October 1999 and July 2001. Seven patients (33%) underwent emergency endovascular procedure. Postoperatively, the patients were followed with CT scans at 1, 3, 6, and 12 months. Follow-up, which averaged 17 months, was 100% complete. THIRTY-DAY RESULTS: No conversions to open repair were necessary. Two patients died (10%), one of acute intestinal ischemia and the other because of multiorgan failure. Four patients showed endoleaks immediately after stenting. Two patients required new endovascular stentgrafts, while the remaining two were treated conservatively. Besides endoleaks, eight major complications occurred in six patients (two stroke, two paraplegia, two respiratory insufficiency, and one renal failure). MID-TERM RESULTS: Three more patients died during the follow-up period. One patient died of heart failure after a complicated postoperative course, 91 days after stenting. The second patient died because of aortic rupture, 139 days after stenting. The third patient died of heart failure, 15 months after the endovascular procedure. The remaining 16 patients are alive and have been regularly controlled by CT scans. No late migration or endoleaks have been detected. In all the survivors, the size of the aneurysm was unchanged or diminished.

CONCLUSIONS

Treatment of descending thoracic aortic aneurysms by endovascular stentgraft devices has good early and mid-term results. More accurate selection of patients may further reduce mortality and morbidity.

Effects of GH and insulin-like growth factor-I on body composition

In this review, different methods to estimate body composition are discussed shortly. The effects by GH on total and visceral fat mass, lean mass, muscle strength and body water are described. Gender differences in the sensitivity to GH administration are reviewed. Finally, a short description of the effects of insulin-like growth factor-I (IGF-I) administration on body composition has been included.

Treatment of femoral pseudoaneurysms. Percutaneous US-guided thrombin injection versus US-guided compression

PURPOSE

Thrombin injection in femoral pseudoaneurysms has been suggested to be superior to traditional US-guided compression. Our aim was to evaluate results with compression therapy with special reference to use of thrombin in case of failure. We also studied 7 patients who underwent primary thrombin injection.

MATERIAL AND METHODS

We retrospectively reviewed all (n=44) femoral artery pseudoaneurysms diagnosed at our department during October 1998-May 1999. US-guided compression with the Femostop device or US-guided thrombin injection (100-1000 IU) was the first choice according to the physicians' preference, followed by the other regime if the first choice was non-successful.

RESULTS

Thirty-nine (89%) of the patients received anticoagulation treatment and/or concomitant antiplatelet drugs. Out of the 44 patients, 37 were treated with compression as the first choice. This regime was successful in 22 (59%). This group included 2 lesions that resolved spontaneously after initially failed compression and 1 deep venous thrombosis after treatment. The persistent 15 pseudoaneurysms after failed compression received thrombin injection, and it was also the primary therapy in 7 patients. Complete thrombosis within the pseudoaneurysm was immediately induced after treatment. One early recurrence required a second injection. No complication of thrombin was noted and no surgery was required.

CONCLUSION

US-guided thrombin injection is an effective treatment for embolisation of pseudoaneurysms. The technique is superior to compression therapy.

Treatment of femoral pseudoaneurysms. Percutaneous US-guided thrombin injection versus US-guided compression

PURPOSE

Thrombin injection in femoral pseudoaneurysms has been suggested to be superior to traditional US-guided compression. Our aim was to evaluate results with compression therapy with special reference to use of thrombin in case of failure. We also studied 7 patients who underwent primary thrombin injection.

MATERIAL AND METHODS

We retrospectively reviewed all (n=44) femoral artery pseudoaneurysms diagnosed at our department during October 1998-May 1999. US-guided compression with the Femostop device or US-guided thrombin injection (100-1000 IU) was the first choice according to the physicians' preference, followed by the other regime if the first choice was non-successful.

RESULTS

Thirty-nine (89%) of the patients received anticoagulation treatment and/or concomitant antiplatelet drugs. Out of the 44 patients, 37 were treated with compression as the first choice. This regime was successful in 22 (59%). This group included 2 lesions that resolved spontaneously after initially failed compression and 1 deep venous thrombosis after treatment. The persistent 15 pseudoaneurysms after failed compression received thrombin injection, and it was also the primary therapy in 7 patients. Complete thrombosis within the pseudoaneurysm was immediately induced after treatment. One early recurrence required a second injection. No complication of thrombin was noted and no surgery was required.

CONCLUSION

US-guided thrombin injection is an effective treatment for embolisation of pseudoaneurysms. The technique is superior to compression therapy.

A method to obtain the same levels of CT image noise for patients of various sizes, to minimize radiation dose

The aim of this study was to develop a method of obtaining the same levels of CT image noise for patients of various sizes to minimize radiation dose. Two CT systems were evaluated regarding noise characteristics using phantoms and dosimetric measurements. Both CT systems performed well at dose levels used in normal clinical imaging, but only one was found to be suitable for low radiation dose applications. The CT system with the lowest noise level was used for further detailed studies. A simple strategy for manual selection of patient-specific scan parameters, considering patient size and required image quality, was implemented and verified on 11 volunteers. Images were obtained with at least the prescribed image quality at significantly reduced radiation dose levels compared with standard scan parameters. Depending on the diameter of the tomographic section, i.e. size of the subject, the dose levels could be reduced to 1-45% of the radiation dose with standard scan parameters (120 kV, 250 mAs, 10 mm). The results indicate a general potential for dose reduction in CT for slim patients. For tissue volume determination, large dose reductions can be achieved by adjusting the scan parameters for each individual. The concept of patient-specific scan parameters could be fully automated in the CT system design, but would require the scan to be specified in terms of image quality rather than X-ray tube load.

Aneurysm sac hygroma: a cause of endotension

PURPOSE

To describe a new pathophysiological mechanism for endotension.

CASE REPORTS

Four patients developed aneurysm sac expansion after repair of abdominal aortic aneurysms, one with a conventional polytetrafluoroethylene (PTFE) graft and the others with a variety of commercially made endografts (2 PTFE, 1 Dacron). Pressures within the sacs were nonpulsatile and approximately half the systemic blood pressure. Attenuation on computed tomography (CT) was significantly less in the sac than in the graft in 3 of the patients. A clear, highly viscous fluid was aspirated from all 4 sacs, supporting the diagnosis of aneurysm sac hygroma. Prominent local hyperfibrinolysis in the sac was combined with signs of local coagulation activation.

CONCLUSIONS

A new mechanism for continued sac expansion based on aneurysm sac hygroma is proposed. Measurement of attenuation may be of diagnostic value. It is further proposed that local hyperfibrinolysis/coagulation may promote rebleeding, liquefaction, and continued expansion analogous to the chronic subdural hematoma.

MRI staging using gadodiamide for soft-tissue tumors of the head and neck region. Results from a phase II trial and a 5-year clinical follow-up

In order to document the safety, tolerability and efficacy of gadodiamide outside CNS, an open, non-drug comparative study was performed in patients with tumors of the head and neck region. Fifty adult patients were included and 48 patients received the contrast medium. The examinations were performed on a 1.5 T imager using transverse, non-enhanced T1- and PD-/T2-weighted conventional spin-echo sequences, followed by a contrast-enhanced transverse T1-weighted sequence. Post-contrast images provided more diagnostic information compared to unenhanced images in 33 of 48 patients (69%). This information was of significant help in four and of moderate help in 14 cases. Post-contrast images compared to non-enhanced T1-weighted showed improvement in lesion delineation for 29 of the 43 patients where a lesion was observed. Only in two patients was the diagnostic information lower post-contrast. A comparison between all pre-contrast images versus contrast medium enhanced showed post-contrast images to give more diagnostic information in 14 and less in nine patients. No patient experienced discomfort in relation to gadodiamide injection. Only one adverse event occurred which was described as thirst, being of moderate intensity. The 5-year clinical outcome was analyzed and compared with the pre-operative staging. The case-books of all patients were reviewed and in 44 patients all information could be found. Of those, 18 were still alive, one with active disease (AAD) and 17 with no evidence of disease (NED). Two of those four patients, where information was incomplete, showed NED and two had died. This trial showed that contrast-enhancement using gadodiamide for evaluation of soft tissue tumors in the head and neck region was safe and provided statistically significant more diagnostic information compared with unenhanced images. MRI, when compared with palpation/inspection, changed tumor staging in approximately 30% of all cases.

Skeletal muscle characteristics, muscle strength and thigh muscle area in patients before and after cardiac transplantation

BACKGROUND

Patients with chronic heart failure demonstrate several skeletal muscle abnormalities. The underlying mechanisms are unclear. After cardiac transplantation, cardiac function is restored, but exercise capacity is still impaired.

AIM

To evaluate the influence of cardiac transplantation on skeletal muscle fibre composition, fibre area and capillarization as well as muscle enzymes, lactate, thigh muscle area and strength.

METHODS

Ten patients were longitudinally investigated before, 1-3 and 6-9 months after transplantation. Ten healthy individuals served as controls. A biopsy from the lateral vastus muscle was obtained and the thigh muscle area was measured with computed tomography. Muscle strength in the knee extensors and exercise capacity were also evaluated.

RESULTS

Muscle lactate was elevated in patients vs. controls (3.6+/-3.0 vs. 1.5+/-0.7 mmol/kg wet wt., P=0.037), and decreased to normal (1.4+/-0.3 mmol/kg wet wt., P=0.038) after transplantation. Citrate synthase activity was decreased in patients (5.6+/-1.5 micromol/g wet wt./min) vs. controls (8.1+/-1.6 micromol/g wet wt./min, P=0.0018), and did not change post transplantation. Patients had decreased number of capillaries in contact with each fibre vs. controls (2.6+/-0.5 vs. 3.5+/-1.0, P=0.039) which persisted post transplantation. Exercise capacity increased after transplantation (74+/-22 vs. 118+/-26 W, P=0.0002), whereas muscle strength did not improve significantly.

CONCLUSION

The persisting intrinsic abnormalities in skeletal muscle after cardiac transplantation may contribute to the impaired exercise capacity observed in cardiac transplant recipients.

Management of vascular injuries using endovascular techniques

Vascular surgery is in a transitional phase. Standard open repair is being replaced by endovascular and minimally invasive techniques. The techniques developed for elective cases are also applicable for injured patients. The introduction of endovascular treatment for emergencies has consequences for both institutional and regional organisation. Success can be achieved only by the prepared team trained with wide elective experience. Endovascular repair of vascular injuries has many advantages, such as remote approach and limited exposure with less surgical stress to the patient. Because the long term effects are only partially known a word of caution is justified. Endovascular repair of vascular trauma is still a developing form of treatment.

Determination of tissue volumes. A comparison between CT and MR imaging

PURPOSE

To evaluate MR imaging for tissue volume measurements.

MATERIAL AND METHODS

Imaging was done with a spoiled gradient echo technique using the human lower leg as a simple model and CT as the reference technique. Areas of adipose tissue, muscle plus skin and bone tissue were evaluated in 5 volunteers using signal intervals (MR) and attenuation intervals (CT) defined by histograms. Volumes were determined from 7 images (MR-7, CT-7), from 70 contiguous images (MR-70), and also from a commercially-available 3D program based on a seeding technique applied according to the operators' judgment (MR-op).

RESULTS

The sum of bone tissue, muscle plus skin and adipose tissue were similar for CT and MR. Compared to CT-7, MR-7 and MR-70 overestimated adipose tissue (0-8%) and muscle plus skin (11-15%), while bone tissue was underestimated (61-78%). Determinations based on the contiguous images or the 7 images were similar (standard error 2-5%). MR-op resulted in pronounced underestimation of muscle plus skin and bone tissue and a minor underestimation of adipose tissue.

CONCLUSION

Valid determinations of adipose tissue volume are possible with MR but further technical development is required for other tissue volumes. The technique applied according to the operators' judgement, as used for 3D surface rendition, is unreliable for tissue volume determinations.

Upper motor neuron lesions: their effect on muscle performance and appearance in stroke patients with minor motor impairment

OBJECTIVE

To evaluate muscular performance and appearance in patients with prior stroke who were ambulatory.

DESIGN

Nonrandomized study.

SETTING

University hospital laboratory.

SUBJECTS

Sixteen persons (11 men, 5 women) with minor motor impairments, 6 to 24 months after stroke, were included. As reference, data were used from a population-based sample of 144 men and women.

MAIN OUTCOME MEASUREMENTS

Muscle performance was evaluated using a Kin-Com dynamometer in both the affected and the nonaffected leg. Peak isometric strength was measured at a 60 degree angle in both extension and flexion. Maximal isokinetic strength was measured at 60 degrees/sec and at 180 degrees/sec. Endurance was evaluated during isometric and dynamic knee extensions. Muscle biopsies were taken on nine patients and muscle tissue areas were determined with computed tomography.

RESULTS

The affected leg was weaker but not different in relative endurance compared with the nonaffected side. The performance of the nonaffected side was somewhat lower than that of a matched reference population. No major difference in fiber composition between the affected and nonaffected legs was noted, except for a lower degree of capillarization in the affected leg.

CONCLUSION

In well-functioning stroke patients with good motor performance, further muscle training that includes resistance exercise might be indicated.

Body weight and body composition changes after treatment of hyperthyroidism

Body composition changes in nine adults with hyperthyroidism were determined with dual energy x-ray absorptiometry and computed tomography at diagnosis and after 3 and 12 months of euthyroidism achieved by surgery, antithyroid drugs, or treatment with radioiodine. Mean body weight was 67.6 kg at diagnosis and increased 2.7 kg (P=0.06) and 8.7 kg (P < 0.001) after 3 and 12 months of euthyroidism, respectively. Basal metabolic rate decreased from 2087 Cal/24 h at diagnosis to 1601 Cal/24 h at 12 months (P=0.001), whereas reported energy intake dropped from 3244 to 2436 Cal/24 h (P=0.01). According to dual energy x-ray absorptiometry, body fat was unchanged at 3 months, but increased by 5.3 kg (P < 0.0001) at 12 months. Fat-free mass increased 2.7 kg (P=0.003) at 3 months and 3.5 kg (P < 0.0001) at 12 months. Changes in bone mineral content and density did not reach significance. According to computed tomography, skeletal muscle plus skin areas increased by 11% (trunk) and 18% (thigh) at 3 months and by 17% (trunk) and 25% (thigh) at 12 months. There was no increase in sc adipose tissue (AT) at 3 months, but at 12 months this AT depot increased by 15% (thigh) and 33% (trunk). Intraperitoneal AT showed a borderline significant increase by 28% (P=0.08) at 3 months and by 40% (P=0.015) at 12 months. Areas of visceral organs and bone tissue of femur did not change significantly during the study. It is concluded that during early recovery from hyperthyroidism, priority is given to the replenishment of skeletal muscles and ip AT, whereas sc AT is increased at a later stage.

Serum leptin concentration and insulin sensitivity in men with abdominal obesity

OBJECTIVE

We have examined the association between generalized adiposity, abdominal adiposity, insulin sensitivity, and serum levels of leptin in a cross-sectional study of abdominally obese men.

RESEARCH METHODS AND PROCEDURES

Thirty men, 48 to 66 years of age with a body mass index (BMI) of between 25 kg/m2 and 35 kg/m2 and a waist hip ratio of >0.95, were included in the study. Serum leptin concentration was measured using radioimmunoassay. Total body fat percentage was determined from total body potassium, abdominal adiposity was measured by computed tomography, and the glucose disposal rate (GDR) was measured during an euglycemic, hyperinsulinemic glucose clamp.

RESULTS

Significant correlations were found between serum leptin concentration and BMI, percentage body fat, abdominal subcutaneous adipose tissue, serum insulin, GDR, and 24-hour urinary-free cortisol. In a multiple regression analysis, it was shown that abdominal subcutaneous adipose tissue, GDR, and BMI explained 72% of the variability of serum leptin concentration. GDR demonstrated an independent inverse correlation with serum leptin concentration.

DISCUSSION

In abdominally obese men with insulin resistance, it was demonstrated that most of the individual variability in serum leptin concentration was explained by the amount of subcutaneous abdominal adipose tissue, insulin sensitivity, and BMI.

Radiation dose reduction in CT: application to tissue area and volume determination

PURPOSE

To study the potential for radiation dose reduction in computed tomographic (CT) determination of adipose and muscle tissue area and volume, which is an application in which lower spatial resolution or higher image noise can be accepted.

MATERIALS AND METHODS

Measurements in vivo (in a healthy man aged 52 years; weight, 80 kg) and in phantoms were performed with two standard clinical CT scanners. Tissue areas were determined, and measurement uncertainties were analyzed. Comparisons were made with simulated and theoretic data.

RESULTS

A 25-fold reduction in radiation dose was achieved and resulted in an effective dose of 13 microSv per section; an accuracy of greater than 5% in area measurements was maintained. The dose savings achieved in this study were close to those that are theoretically possible.

CONCLUSION

Further dose reduction to about 1 microSv may be possible for this application. Large dose reductions are possible in CT determinations of tissue area and volume, which makes this application available also in large randomized studies in which high-performance clinical standard scanners are used. This work demonstrates that modern CT technology may have a large potential for dose reduction in specific applications.

Dose reduction for body composition measurements with CT

The purpose was to obtain reliable measures of fat and muscle tissue areas with CT at a reduced radiation dose level. Repeated CT-scans with four different levels of reduced radiation dose were perfomed on a water phantom and a volunteer at the L4-L5 level. Dose measurements were performed in a phantom and free in air. A histogram model function for fat, muscle and partial volume affected voxels was proposed and used in the analysis of image noise. The result was at most a 25-fold reduction in radiation dose with an image noise of 40 HU but only a minor influence on the tissue area determination [corrected].