Rob J. Th. J. Welten

In vivo detection of hemorrhage in human atherosclerotic plaques with magnetic resonance imaging

To investigate the performance of high‐resolution T1‐weighted (T1w) turbo field echo (TFE) magnetic resonance imaging (MRI) for the identification of the high‐risk component intraplaque hemorrhage, which is described in the literature as a troublesome component to detect.

Dynamic contrast-enhanced MR imaging of carotid atherosclerotic plaque: model selection, reproducibility, and validation

PURPOSE To compare four known pharmacokinetic models for their ability to describe dynamic contrast material-enhanced magnetic resonance (MR) imaging of carotid atherosclerotic plaques, to determine reproducibility, and to validate the results with histologic findings. MATERIALS AND METHODS The study was approved by the institutional medical ethics committee. Written informed consent was obtained from all patients. Forty-five patients with 30%-99% carotid stenosis underwent dynamic contrast-enhanced MR imaging. Plaque enhancement was measured at 16 time points at approximately 25-second image intervals by using a gadolinium-based contrast material. Pharmacokinetic parameters (volume transfer constant, K(trans); extracellular extravascular volume fraction, v(e); and blood plasma fraction, v(p)) were determined by fitting a two-compartment model to plaque and blood gadolinium concentration curves. The relative fit errors and parameter uncertainties were determined to find the most suitable model. Sixteen patients underwent imaging twice to determine reproducibility. Carotid endarterectomy specimens from 16 patients who were scheduled for surgery were collected for histologic validation. Parameter uncertainties were compared with the Wilcoxon signed rank test. Reproducibility was assessed by using the coefficient of variation. Correlation with histologic findings was evaluated with the Pearson correlation coefficient. RESULTS The mean relative fit uncertainty (±standard error) for K(trans) was 10% ± 1 with the Patlak model, which was significantly lower than that with the Tofts (20% ± 1), extended Tofts (33% ± 3), and extended graphical (29% ± 3) models (P < .001). The relative uncertainty for v(p) was 20% ± 2 with the Patlak model and was significantly higher with the extended Tofts (46% ± 9) and extended graphical (35% ± 5) models (P < .001). The reproducibility (coefficient of variation) for the Patlak model was 16% for K(trans) and 26% for v(p). Significant positive correlations were found between K(trans) and the endothelial microvessel content determined on histologic slices (Pearson ρ = 0.72, P = .005). CONCLUSION The Patlak model is most suited for describing carotid plaque enhancement. Correlation with histologic findings validated K(trans) as an indicator of plaque microvasculature, and the reproducibility of K(trans) was good.

In situ preservation of kidneys from donors after cardiac death: results and complications.

Objectives:To describe the results and complications of in situ preservation (ISP) of kidneys from donors after cardiac death (DCD). Background:DCD donors are increasingly being used to expand the pool of donor kidneys. ISP reduces warm ischemic injury which is associated with DCD donation. Methods:Insertion of a double-balloon triple-lumen catheter allows selective perfusion of the abdominal aorta to preserve the kidneys in situ. From January 2001 until August 2005, 133 ISP procedures were initiated in our procurement area. Results:Fifty-six (42%) ISP procedures led to transplantation; in the remaining 77 cases (58%), the donation procedure was abandoned or both kidneys were discarded because of ISP complications (n = 31), poor graft quality (n = 23), no consent for donation (n = 13), medical contraindications (n = 8), or unknown cause (n = 2). Increasing donor age (odds ratio (OR) 1.06 per year, P < 0.001) and uncontrolled DCD donation (OR 5.4, P < 0.001) were independently correlated with ISP complications. After transplantation, prolonged double-balloon triple-lumen catheter insertion time was an independent predictor of graft failure (OR 2.0, P = 0.05). Selected controlled DCD donors were managed by rapid laparotomy and direct aortic cannulation; graft survival of these kidneys was superior to kidneys from controlled DCD donors managed by ISP. Conclusions:A minority of initiated ISP procedures led to transplantation, resulting in a high workload compared with donation after brain death. The association between increasing catheter insertion time and inferior graft outcome emphasizes the need for fast and effective surgery. Therefore, rapid laparotomy with direct aortic cannulation is preferred over ISP in controlled DCD donation. Despite these limitations, we have expanded our donor pool 3- to 4-fold by procuring DCD kidneys that were preserved in situ.

Comparison of lipid-rich necrotic core size in symptomatic and asymptomatic carotid atherosclerotic plaque: Initial results.

To investigate the potential difference in the size of the lipid‐rich necrotic core (LRNC) in carotid plaques of symptomatic patients versus asymptomatic patients. Pathological studies established that a large LRNC is an important feature of vulnerable atherosclerotic plaque. Previously, we have demonstrated a high correlation between semiquantitative analysis of the LRNC size in T1‐weighted (w) turbo field echo (TFE) MR images and histology.

Gadofosveset-enhanced magnetic resonance imaging of human carotid atherosclerotic plaques : a proof-of-concept study

Objective:To investigate the potential of gadofosveset-enhanced MR imaging for the characterization of human carotid atherosclerotic plaques. Materials and Methods:Sixteen (9 symptomatic, 7 asymptomatic) patients with 70% to 99% carotid stenosis (according to NASCET criteria) were included (13 men, 3 women, mean age 67.6 years). All patients underwent baseline precontrast MR imaging of the carotid plaque. Immediately after completion of the baseline examination, 0.03 mmol/kg gadofosveset was administered. At 24 hours postinjection, the acquisition was repeated. Twelve patients were scheduled for carotid endarterectomy. Carotid endarterectomy specimens were HE-, CD31-, CD68-, and albumin-stained to correlate signal enhancement with plaque composition, intraplaque microvessel density, and macrophage and albumin content. A random intercept model was used to compare signal enhancement between symptomatic and asymptomatic patients, adjusting for size of various plaque components. This study was approved by the institutional medical ethics committee. All participants gave written informed consent. Results:Signal enhancement (SE) of the plaque was significantly higher in symptomatic patients compared with asymptomatic patients (median log SE 0.182 vs. −0.109, respectively, P < 0.001). A positive association (as expressed by a regression coefficient &bgr; = 0.0035) was found between signal enhancement on the log scale and intraplaque albumin content (P = 0.038). There was no association between signal enhancement and various other plaque components. Conclusion:In this study, the potential of gadofosveset-enhanced human carotid plaque MR imaging for identification of high-risk plaques was demonstrated. Signal enhancement of the plaque after administration of gadofosveset was associated with differences in intraplaque albumin content. Although promising, we emphasize that these results are based on a small patient population. Larger prospective studies are warranted.

Comparison of single‐sequence T1w TFE MRI with multisequence MRI for the quantification of lipid‐rich necrotic core in atherosclerotic plaque

To prospectively determine the accuracy of semiquantitative analysis of the amount of lipid‐rich necrotic core (LRNC) in atherosclerotic plaque using multi‐ as well as single‐sequence T1‐weighted (w) turbo field echo (TFE) MRI. Histology served as a reference standard.

Ruptured AAA in a patient with a horseshoe kidney: emergent treatment using the talent acute endovascular aneurysm repair kit.

Purpose: To report emergent endovascular repair of a ruptured abdominal aortic aneurysm (AAA) in a patient with a horseshoe kidney. Case Report: A 78-year-old man with a horseshoe kidney presented with a contained rupture of a 72-mm AAA. After urgent computed tomographic angiography (CTA) documented the blood supply to the kidney and the suitability of the aneurysm for endovascular repair, the patient was given a local anesthetic. An aortomonoiliac stent-graft constructed from components provided in a Talent Acute Endovascular Aneurysm Repair Kit was inserted successfully. The procedure was completed with placement of a contralateral common iliac artery occluder and a femorofemoral bypass graft. No complications were encountered, and the patient was discharged with an excluded aneurysm on the fourth postoperative day. At 3 months, aneurysm exclusion was confirmed by CTA, and no endoleak was present; the retroperitoneal hematoma had disappeared. The patient remains in good general condition 8 months after treatment Conclusions: The advantages of endovascular aneurysm repair in the emergency setting can facilitate rapid recovery in patients with symptomatic or ruptured aneurysms, especially those having a horseshoe kidney.

Circulating biomarkers and abdominal aortic aneurysm size

BACKGROUND Abdominal aortic aneurysm (AAA) is a degenerative disease of the abdominal aorta leading to progressive dilatation, intra-luminal thrombus (ILT) formation, and rupture. Understanding the natural history of AAA is essential, because different processes and, therefore, different biomarkers, could be involved at each stage of disease progression. The purpose of the present study was to investigate the relationship between systemic expression of biomarkers of inflammation and extracellular matrix remodeling and aneurysm size in AAA patients. METHODS AND RESULTS All consecutive patients admitted to the (out-) patient clinic of the surgical department of two large community centers were prospectively included. Patients were divided into three groups based on their aneurysm diameter: small (30-44 mm; n = 59), medium-sized (45-54 mm; n = 64) or large (≥ 55 mm; n = 95) AAA. Linear regression modeling showed that age and serum hsCRP concentration were positively associated, whereas serum HDL and IgG concentrations were negatively associated with aneurysm size. This regression model was corrected for possible bias due to statin use and center of inclusion; and also indicated that in general men have larger aneurysms compared with women. CONCLUSIONS Different aneurysm sizes showed different expression pattern of HDL, IgG, and hsCRP. These biomarkers may be useful in predicting AAA progression.

Anterior tibial artery aneurysm: Case report and literature review

INTRODUCTION We present a patient with a true anterior tibial artery aneurysm without any causative history. PRESENTATION OF CASE A 59 year old male was referred with a swelling on his left lateral ankle which he noticed 2 months ago, with symptoms of soaring pain. Additional radiological research showed a true arterial tibialis anterior aneurysm. True anterior tibial artery aneurysm is a rare condition. The aneurysm was repaired by resection and interposition of a venous bypass. DISCUSSION Patients may complain about symptoms like calf pain, distal ischemia, paresthesias due to nerve compression and the presence of a pulsating or increasing mass. Symptomatic aneurysms require surgical intervention, where bypass with a venous saphenous graft have shown good patency and endovascular treatment have shown good short term results. Asymptomatic and small aneurysm can be followed for several years with DUS. CONCLUSION Clinical features, radiographic findings, surgical management, and a review of the literature on true anterior tibial aneurysms are discussed.

Primary aortoduodenal fistula and Q-fever

Patients with abdominal aortic aneurysm (AAA) are prone to vascular infection with chronic Q-fever. There is a rising incidence of up to 8% of chronic Q-fever in The Netherlands. Increased vascular aortic aneurysm infection with chronic Q-fever is reported. This report shows two rare cases of primary aortoduodenal fistulae in patients with chronic Q-fever and an AAA. We describe the clinical symptoms, diagnostic tools for detection of Coxiella burnetii infection and treatment.