Activated adaptive immune system in dissected bicuspid aortic valve aortas: trigger for dissection?

Background/Introduction

Bicuspid aortic valve (BAV) is associated with ascending aorta aneurysms and dissections. Presently, genetic factors and pathological flow patterns are considered responsible for aneurysm formation in BAV. Despite, indication for preventive surgery is presently only defined by vessel diameter which is poor marker for dissection, as it does not take other processes responsible for the vulnerability of the aorta into account.

Purpose

Inflammation is not considered a player in BAV aortopathy. We introduce a quantitative immunohistochemistry (IHC) approach to sensitively look at the potential role of both the innate and adaptive immune system in BAV aortopathy.

Methods

Dilated (n=8), non-dilated (n=14) and dissected (n=4) BAV ascending aortas were collected during surgery or from post-mortem donors. Median time from symptoms to surgery for dissections was just over 4 hours. Tissue was stained with a novel 8-colour IHC technique allowing for simultaneous visualization of 6 markers per slide, completed with DAPI nuclear counter-stain and elastin fiber autofluorescence. One panel focused on the adaptive immune system (identifying B cells and classic dendritic cells type 2 (cDC2s) and phenotyping T cells), and the other on the innate immune system (assessing macrophage polarization and neutrophil extravasation). All cells were identified and comprehensively phenotyped using automated quantitative analysis.

Results

Aneurysm formation was associated with an organized and consistent increase of lymphocytes in the adventitia. B cell follicles and helper T cell expansion were identified, suggestive of a targeted adaptive immune response (Fig. 1a). Only dissected aortas showed a statistically significant increase of helper T (p=0.3) and cDC2s (p=0.3) in the media, when compared to non-dilated and dilated samples (Fig. 1b). The short time between dissection symptoms and surgery suggests these cells were present before the dissection occurred. Furthermore, aneurysms and dissections are associated with a shift in macrophage phenotype to the more aggressive M1-like subset. In summary, we found that a progression of aggressive immune cells in the adventitia and media was correlated to a progression in disease state; from normal to dilated to dissected.

Conclusions

Aorta dilatation in patients with BAV is associated with an expansion of B and helper T cells in the adventitial compartment without changes in the media. This result might indicate an antigen-driven adaptive immune response. Only dissections show an increase in helper T cells and cDC2s in the media, together with polarization of macrophages to a more M1-like phenotype. We hypothesize that antigen-specific helper T cells expand in the adventitia, migrate to the media, and then potentiate macrophages which can eventually lead to tissue degeneration. These associations could shine light on the final step in the deterioration of the aorta towards a dissection.

Figure 1. Microscopy results

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): TTW-NWO open technology grant (STW-14716), ERC-2014-StG-336454-CoNQUeST

Adrenal insufficiency is a contraindication for omalizumab therapy in mast cell activation disease: risk for serum sickness

Omalizumab is an effective therapeutic humanized murine IgE antibody in many cases of primary systemic mast cell activation disease (MCAD). The present study should enable the clinician to recognize when treatment of MCAD with omalizumab is contraindicated because of the potential risk of severe serum sickness and to report our successful therapeutic strategy for such adverse event (AE). Our clinical observations, a review of the literature including the event reports in the FDA AE Reporting System, the European Medicines Agency Eudra-Vigilance databases (preferred search terms: omalizumab, Xolair®, and serum sickness) and information from the manufacturer’s Novartis database were used. Omalizumab therapy may be more likely to cause serum sickness than previously thought. In patients with regular adrenal function, serum sickness can occur after 3 to 10 days which resolves after the antigen and circulating immune complexes are cleared. If the symptoms do not resolve within a week, injection of 20 to 40 mg of prednisolone on two consecutive days could be given. However, in MCAD patients whose adrenal cortical function is completely suppressed by exogenous glucocorticoid therapy, there is a high risk that serum sickness will be masked by the MCAD and evolve in a severe form with pronounced damage of organs and tissues, potentially leading to death. Therefore, before the application of the first omalizumab dose, it is important to ensure that the function of the adrenal cortex is not significantly limited so that any occurring type III allergy can be self-limiting.

Adjustment for time-invariant and time-varying confounders in 'unexplained residuals' models for longitudinal data within a causal framework and associated challenges

‘Unexplained residuals’ models have been used within lifecourse epidemiology to model an exposure measured longitudinally at several time points in relation to a distal outcome. It has been claimed that these models have several advantages, including: the ability to estimate multiple total causal effects in a single model, and additional insight into the effect on the outcome of greater-than-expected increases in the exposure compared to traditional regression methods. We evaluate these properties and prove mathematically how adjustment for confounding variables must be made within this modelling framework. Importantly, we explicitly place unexplained residual models in a causal framework using directed acyclic graphs. This allows for theoretical justification of appropriate confounder adjustment and provides a framework for extending our results to more complex scenarios than those examined in this paper. We also discuss several interpretational issues relating to unexplained residual models within a causal framework. We argue that unexplained residual models offer no additional insights compared to traditional regression methods, and, in fact, are more challenging to implement; moreover, they artificially reduce estimated standard errors. Consequently, we conclude that unexplained residual models, if used, must be implemented with great care.

Blood and Cerebrospinal Fluid α-Tocopherol and Selenium Concentrations in Neonatal Foals with Neuroaxonal Dystrophy

Background

Equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (NAD/EDM) is a neurodegenerative disorder affecting genetically predisposed foals maintained on α‐tocopherol (α‐TP)‐deficient diet.

Objective

Intramuscular α‐TP and selenium (Se) administration at 4 days of age would have no significant effect on serum or cerebrospinal fluid (CSF) α‐TP in healthy foals. Serum and CSF α‐TP, but not Se, would be significantly decreased in NAD/EDM‐affected foals during first year of life.

Animals

Fourteen Quarter horse foals; 10 healthy foals supplemented with 0.02 mL/kg injectable α‐TP and Se (n = 5) or saline (n = 5) at 4 days of age and 4 unsupplemented NAD/EDM‐affected foals.

Methods

Complete neurologic examinations were performed, blood and CSF were collected before (4 days of age) and after supplementation at 10, 30, 60, 120, 180, 240, and 360 days of age. Additional blood collections occurred at 90, 150, 210, and 300 days. At 540 days, NAD/EDM‐affected foals and 1 unsupplemented healthy foal were euthanized and necropsies performed.

Results

Significant decreases in blood, CSF α‐TP and Se found in the first year of life in all foals, with most significant changes in serum α‐TP from 4–150 days. Dam α‐TP and Se significantly influenced blood concentrations in foals. Injection of α‐TP and Se did not significantly increase CSF Se, blood or CSF α‐TP in healthy foals. NAD/EDM‐affected foals had significantly lower CSF α‐TP through 120 days.

Conclusions and Clinical Importance

Injection of α‐TP and Se at 4 days of age does not significantly increase blood or CSF α‐TP. Despite all 14 foals remaining deficient in α‐TP, only the 4 genetically predisposed foals developed NAD/EDM.

Lymphatic Interventions for Treatment of Chylothorax

PURPOSE

To determine effectiveness of lymphatic interventional procedures for treatment of chylothorax.

MATERIAL AND METHODS

Analysis of interventions performed from 2001 to 2014.

RESULTS

In 21 patients with therapy resistant chylothorax a lymphatic radiological intervention was attempted, which could be performed in 19 cases: 17 thoracic duct embolizations (15 transabdominal, one transzervical and one retrograde transvenous procedure), 2 percutaneous destructions of lymphatic vessels, one CT-guided injection of ethanol next to a duplicated thoracic duct. Fourteen of seventeen (82.3 %) of the technically successful embolizations lead to clinical cure. This encluded three patients with prior unsuccessful surgical thoracic duct ligation. Also the injection of ethanol was clinically effective. Complications were a bile peritonitis requiring operation, and one clinical deterioration of unknown cause.

CONCLUSION

Interventional lymphatic procedures allow for effective treatment in many cases of chylothorax, and should be considered early during treatment.

KEY POINTS

• Thoracic duct embolization is an effective treatment method for chylothorax. • If embolization is impossible, percutaneous lymphatic destruction or injection of sclerosants/tissue adhesive next to the thoracic duct may be tried.

[Our moral ancestors: determining adjustment sets in causal diagrams with ease]

This article is concerned with the application of causal diagrams (also called DAGs) to the following 2 tasks, which are often faced in epidemiology: (1) a posteriori verification of the adjustment performed in an empirical study; (2) a priori identification of appropriate covariate sets for adjustment during study design. Causal diagram theory provides several methods for solving both of these tasks. However, some of these methods are computationally highly demanding, and thus cannot be carried out by hand and even pose problems for fast modern computers. In order to ease everyday work with causal diagrams, we discuss here the most efficient method known to date for performing the stated tasks. This method is based on the so-called "ancestor moral graph" construction by Lauritzen et al. and enables epidemiologists to solve at ease even large causal diagrams with dozens of variables and associations. Moreover, the presented method is well-suited for implementation in computer software, like it has been done in the DAG program and its graphical counterpart DAGitty.

Surgical management and outcome of a type-III Salter-Harris fracture of the frontal plane of the distal radial physis in a foal

CASE HISTORY

A 4-week-old Thoroughbred filly presented with lameness of acute, severe onset of the left foreleg (LF) of 3 days' duration.

CLINICAL FINDINGS

Diffuse swelling was present around the distal radius and carpus of the LF. Carpal varus that could be reduced manually was present. Radiographs revealed an intra- articular frontal-plane fracture in the distal radial epiphysis, which continued cranially through the distal radial physis (DRP). The lateral aspect of the DRP was wider than expected. Latero-medial carpal instability was resolved by placement of a lag screw from the dorsal midline through the epiphysis across the fracture. The DRP closed prematurely, resulting in a non-reducible carpal varus deformity, which was partially corrected surgically, and reduced the length of the limb.

DIAGNOSIS

Frontal-plane Salter-Harris type-III DRP fracture and varus deformity due to physeal injury.

CLINICAL RELEVANCE

Frontal-plane Salter-Harris type- III fractures do not appear to have been previously reported in horses and may be associated with a poor prognosis for athletic activity.

Prostate cancer tissue is masked by bicalutamide: a case report

Prostate cancer is the most common malignant tumor in men. Recently, a slightly decreased frequency of margin positivity following neoadjuvant bicalutamide treatment due to tumor shrinkage was reported. Trials investigating other anti-androgens in the past also reported lower frequencies of surgical margin positivity, but patients outcome has not improved. In this case, local recurrence was confirmed by needle biopsy in a patient five years following radical prostatectomy for prostate adenocarcinoma. After therapy with 50 mg bicalutamide for a month, the tumour was resected. Despite of detailed histological work-up and immunohistochemistry cancer suspicious lesions were not found. We think that bicalutamide may be capable of masking prostate cancer cells.

Aggressive angiomyxoma of the prostate mimicking benign prostatic hyperplasia

Aggressive angiomyxoma (AAM) is a locally invasive soft tissue tumor with a high risk of local recurrence but without metastatic spread. The mesenchymal tumor is relatively site-specific and has a peak incidence in females in their 2nd or 4th decade. Only few cases in males have been reported in the literature. We describe what we think is the first case of an aggressive angiomyxoma arising in the prostate presenting with classical symptoms of benign prostatic hyperplasia.

[Diagnostic imaging of vascular leiomyosarcomas]

Primary vascular leiomyosarcomas are very rare tumors, with the venous variety most often arising from the inferior caval vein and the arterial variety from the pulmonary artery. The tumors show either an exclusive intra- or extravascular pattern or a mixed growth pattern. The clinical symptoms depend on tumor location, with intraluminal tumors of the inferior caval vein causing edema or a Budd-Chiari syndrome. Leiomyosarcomas of the pulmonary artery can mimic chronic central or recurrent peripheral pulmonary embolism. Contrast enhanced spiral CT with multiplanar reconstruction is the diagnostic method of choice when a vascular leiomyosarcoma is suspected. MRI with MR-angiography can be added. If a tumor of undetermined origin shows a broad contact with a vessel and/or an intraluminal component, possible primary vascular leiomyosarcoma should be included in the differential diagnosis.

Limitations and pitfalls of Couinaud's segmentation of the liver in transaxial Imaging

The segmental anatomy of the human liver has become a matter of increasing interest to the radiologist, especially in view of the need for an accurate preoperative localization of focal hepatic lesions. In this review article first an overview of the different classical concepts for delineating segmental and subsegmental anatomy on US, transaxial CT, and MR images is given. Essentially, these procedures are based on Couinaud's concept of three vertical planes that divide the liver into four segments and of a transverse scissura that further subdivides the segments into two subsegments each. In a second part, the limitations of these methods are delineated and discussed with the conclusion that if exact preoperative localization of hepatic lesions is needed, tumor must be located relative to the avascular planes between the different portal territories.

[MRI in cavernous transformation of the portal vein: secondary biliary abnormalities and portoportal collaterals]

PURPOSE

Evaluation of portoportal collateral vessels and associated biliary abnormalities in patients with cavernous transformation of the portal vein by MRI.

MATERIAL AND METHODS

Review of 34 MRI examinations performed on patients with angiographically or MR-angiographically proven cavernous transformation. The analysis included the pattern of the portoportal collateral circulation and the abnormalities of the biliary system, such as wall thickening, stenosis, dilations and irregularities of the extra-and intrahepatic bile ducts.

RESULTS

23 (67.6%) of 34 patients with cavernous transformation had paracholedochal portoportal collateral vessels, with 22 (64.7%) showing visible luminal channels. Epicholedochal venous collaterals could be observed in 8 (23.5%) patients. 24 (70.5%) of 34 patients demonstrated biliary abnormalities due to portoportal collaterals, leading to stenosis with dilatation of the proximal bile ducts in 8 (23.5%) patients. The ductal walls were irregular in 7 (20.5%) patients, and thickened in 11 (32.3%). The gallbladder wall was thickened in 4 (12.9%) patients.

CONCLUSION

Portoportal collaterals in patients with cavernous transformation of the portal vein can be identified by MRI. These collaterals frequently alter the biliary system, which must be considered in differential diagnosis of biliary abnormalities observed in the presence of portoportal collaterals.

FDG-PET findings of vertebral compression fractures in osteoporosis: preliminary results

The aim of this study was to evaluate FDG-PET findings in patients with osteoporosis or preclinical osteoporosis and acute vertebral compression fractures in order to determine whether FDG-PET has a value for distinction of pathological from osteoporotic vertebral fractures. 17 patients with a spontaneous compression fracture of the spine were evaluated by bone scanning with Tc-99m HDP, positron emission tomography with fluorine-18 deoxyglucose (FDG-PET) and magnetic resonance imaging (MRI). Osteoporosis had been established in all cases by X-ray and osteodensitometry. PET and bone scan images were scored independently from 0 (no pathological uptake) to 4 (definitive pathological uptake) by two blinded nuclear medicine physicians. The results of the blinded scoring were compared to MRI findings which served as gold standard. In 13 out of 17 patients, MRI demonstrated a vertebral fracture generating from osteoporosis. In 12 of these 13 cases, PET scans were scored with 0 or 1 and categorized as true negative. Standard uptake values (SUV) ranged between 1.1 and 2.4. In one of the 13 patients, PET was interpreted false positive with an uptake score of 3 (SUV = 2.9). Of the 17 patients, MRI revealed a pathological fracture caused by spondylodiscitis in three patients and by plasmacytoma in one patient. In these patients, all PET scans were highly positive with a score of 3 and 4 and SUV values between 3.8 to 9.8. The bone scans of all 17 patients were positive with scores of 3 or 4 but a differentiation between osteoporotic and pathological fractures was not possible. Our preliminary results indicate that acute vertebral fractures that originated from osteoporosis or preclinical osteoporosis tend to have no pathologically increased FDG uptake. Since a high FDG uptake is characteristic for malignant and inflammatory processes, use of FDG-PET may have potential value for differentiation between osteoporotic and pathological vertebral fractures.

Hemodynamic effects of propranolol and nitrates in cirrhotics with transjugular intrahepatic portosystemic stent-shunt

BACKGROUND

The combination of tailored TIPS with vasoactive drugs might allow reduction of the rate of subsequent shunt-related sequelae.

METHODS

We studied cirrhotic patients 8 weeks (median) after TIPS insertion (8-10 mm) for variceal bleeding. Nitrate (0.1 mg/kg) and propranolol (0.15 mg/kg) alone or combined (same dosages) were infused (I h) sequentially at 1-h intervals (n = 17). Similarly, propranolol was randomly compared to placebo (NaCl, n = 14). We measured mean arterial pressure (MAP, mmHg), heart rate (HR) and portal pressure gradient (PPG: portal minus central venous pressure) prior to and after drugs.

RESULTS

Propranolol reduced PPG (mean +/- s, mmHg) significantly (14.8 +/- 3.7 versus 12.1 +/- 3.7; -21% +/- 10%; P < 0.001), while nitrates alone (14.3 +/- 3.4 versus 13.7 +/- 3.4; -11% +/- 3%; P=0.06) or nitrates plus propranolol (12.9 +/- 4 versus 12.4 +/- 4; -7% +/- 8%; P=0.2) induced only minor additive effects on portal pressure. However, nitrate reduced MAP (P < 0.001) and increased HR (P < 0.01), whereas propranolol reduced only HR (P < 0.001) with unchanged MAP, and the combination decreased MAP (P < 0.001). Compared to placebo (no effect), propranolol decreased PPG (14.4 +/- 5.6 versus 11.1 +/- 5.5; -23% +/- 11%; P < 0.001) and HR (P < 0.001). Overall, most patients (92%) responded to propranolol and 54% showed a marked PPG decrease (>20%).

CONCLUSIONS

Propranolol significantly reduced portal pressure in cirrhotic patients after TIPS, whereas nitrates induced only minor benefit. TIPS-treated patients might therefore profit from additive propranolol therapy allowing limited shunts to be applied initially and/or to reduce the need for TIPS revisions in the case of shunt-dysfunction during follow-up.

[Visceral artery aneurysms]

The purpose of this article is to review the etiology, clinical presentation and treatment options of visceral artery aneurysms (VAA) on the basis of our experiences. Visceral artery aneurysms are uncommon lesions with a frequency of 0,1-0,2 % in autopsy statistics. In fact many visceral artery aneurysms still present first with a rupture (22 %) and despite emergency laparotomies the mortality rate is about 8,5 %. The course of disease often is disastrous due to rupture of the aneurysms or thromboembolic complications, emphasizing the importance to be aware of this differential diagnosis of abdominal pain. This article covers 9 patients with VAA. 3 patients each revealed an a. lienalis aneurysm and a. gastrica aneurysm, resp. In the other 3 patients an aneurysm of the a. gastroepiploica, the a. pancreatico-duodenalis and the a. mesenterica superior resp. was proven. In 8 of 9 patients a surgical therapy of the VAA took place. Only 2 patients (22 %) were interventionally treated. 1 patient deceased due to postoperative hemorrhage. Both the surgical and the radiological intervention therapy are available for treatment of the VAA. The decision on the choice of the therapeutic procedure should be made on an individual basis.

Improving the detectability of focal liver lesions on T2-weighted MR images: ultrafast breath-hold or respiratory-triggered thin-section MRI?

The purpose of this study was to determine whether a respiratory-triggered (RT) T2-weighted turbo spin-echo (TSE) sequence with thin section can improve the detectability of focal liver lesions compared to a breath-hold (BH) T2-weighted TSE sequence. In 25 patients an RT TSE with 8-mm sections (8-TSE RT) and 5-mm sections (5-TSE RT) and a BH TSE sequence with 8-mm sections (8-TSE BH) were performed. Forty-one focal liver lesions (mean: 1.8 +/- 1.2 cm; 14 lesions < or =1 cm; 27 lesions >1 cm) were evaluated. The 5-TSE RT was significantly better in lesion detection compared to the 8-TSE BH sequence for all sizes of lesions (40/41 vs. 33/41; P = 0.014). For lesions >1 cm no relevant differences in the detection rate of the sequences were found (8-TSE RT, 26/27; 5-TSE RT, 26/27; 8-TSE BH, 25/27), for lesions < or =1 cm the 5-TSE RT provided significantly better sensitivity than the 8-TSE BH (14/14 vs. 8/14, P = 0.015). The results of this study suggest that lesion detection could be significantly improved by using an RT TSE sequence with thin sections compared with a BH TSE sequence.

Radiological signs of osteitis around extramedullary metal implants. A radiographic-microbiological correlative analysis in rabbit tibiae after local inoculation of Staphylococcus aureus

Radiographic changes in the early stages of osteomyelitis may be subtle and, especially after plate osteosynthesis, frequently missed. A previously described experimental model of local bacterial infection was used in an attempt to determine the reliability of specific changes on conventional radiographs for the diagnosis of osteitis after metal-plate implantation and subsequent inoculation of Staphylococcus aureus in rabbit tibiae. Roentgenograms of the treated limbs were evaluated, and seven radiographic parameters, to which numerical scores were assigned, were determined for each bone. Our results substantiate the conclusion that a radiographically verified periosteal reaction is a constant and early skeletal feature of acute osteomyelitis and has the strongest association to the microbiological results (P < 0.05), emphasising its high predictive value. Plate implantation does not notably impede the diagnosis of osteomyelitis. An association between the amount of inoculated bacteria and the extent of radiographic changes could be found. The results of this present study closely resemble those described in man and suggest that this model may be useful for future experimental investigations in determining a score judging the severity of osseous involvement in local bacterial infection after plate osteosynthesis.

[Value of selective MIP reconstructions in respiratory triggered 3D TSE MR-cholangiography on a workstation in comparison with MIP standard projections and single-shot MRCP]

PURPOSE

Comparison of anatomical visualisation and diagnostic value of selective MIP reconstructions of respiratory triggered 3D-TSE-MRCP versus standard MIP reconstructions and single-shot MRCP.

MATERIAL AND METHODS

50 patients with pancreaticobiliary disease were examined at 1.5 Tesla (ACS NT II, Philips Medical Systems) using a breath-hold single-shot (SS) and a respiratory triggered 3D-TSE-MRCP technique in 12 standard MIP projections. Additional selective MIP reconstructions with different slice thickness (2, 4, 10 cm) and projections were performed on a workstation. Visualization of the pancreaticobiliary system and the diagnostic value of the examinations were analysed.

RESULTS

Single-shot and 3D-TSE in standard projections showed comparable anatomical visualisation. On selective MIP reconstructions the biliary system (SS p < 0.002; 3D-TSE p < 0.000) and the periampullary region (SS p < 0.000; 3D-TSE p < 0.003) were more clearly seen than on SS and standard MIP reconstructions. Furthermore, superior visualisation of the pancreatic duct could be achieved with additional selective MIP reconstructions in contrast to standard MIP (p < 0.003). Sensitivity and diagnostic accuracy showed superior results for selective and standard MIP reconstructions, but no significant differences between the three techniques were found.

CONCLUSION

SS and standard MIP reconstructions showed comparable anatomical visualisation. Selective MIP postprocessing on a workstation offers a better visualisation of the pancreaticobiliary system and is useful for detecting pathological alterations.

[Obstruction of surgical portosystemic shunts in the early postoperative phase: interventional treatment by angioplasty with stent implantation]

PURPOSE

Recurrent variceal bleeding in patients treated with surgical porto-systemic shunting is most often due to shunt stenoses or occlusion. Radiological interventional procedures are a possible method of therapy and our experience herein is described in this report.

PATIENTS AND METHODS

From 1997 to 1999 54 patients with recurrent variceal bleeding were treated with a surgical porto-systemic shunt procedure. Of these early shunt occlusion occurred in 5 patients, which was treated with percutaneous transcatheter techniques.

RESULTS

In only one patient was PTA alone sufficient to reestablish shunt patency, in four patient stent placement was necessary in addition. In the follow-up period 1 patient died 26 month after intervention with (autopsy-proven) patent shunt, in one patient shunt reocclusion occurred after 11 months and in 3 patients the shunt is still patent.

CONCLUSIONS

PTA, if necessary in combination with stent placement, is an attractive alternative method of therapy in case of an early surgical porto-systemic shunt occlusion.

[Diagnosis of intramural bile duct varicose veins ("pseudo-cholangiocarcinoma sign"]

We report the case of a patient with portal hypertension and portal vein thrombosis who was admitted to hospital for evaluation prior to a scheduled portosystemic shunt operation. Ultrasound examination revealed dilatation of intrahepatic bile ducts and echogenic thickening of the walls of both right and left main bile ducts as well as the common bile duct, highly suspicious of a carcinoma. Further evaluation, however, showed a varicosis of the bile duct walls to be the cause of the thickening of the walls, the varicosis resulting from the long-standing cavernous transformation of the portal vein and the portal hypertension. This tumour-like thickening of the walls, caused by numerous tiny varicose veins, is also known as "Pseudo-cholangiocarcinoma sign" in the Anglo-American world.

Detectability and detection rate of acute cerebral hemisphere infarcts on CT and diffusion-weighted MRI

Our purpose was to compare the detectability and detection rate of acute ischaemic cerebral hemisphere infarcts on CT and diffusion-weighted MRI (DWI). We investigated 32 consecutive patients with acute hemisphere stroke with unenhanced CT and DWI within 6 h of stroke onset. The interval between CT and DWI ranged from 15 to 180 min (mean 60 min). Infarct detectability on CT and DWI was determined by comparing the initial CT, DWI and later reference images in a consensus reading of five independent examiners. The "true" detection rate was assessed by analysing all single readings. Two patients had intracerebral haematomas on DWI and CT and were excluded. There were 27 patients with ischaemic infarcts; all were visible on DWI and proven by follow-up. DWI was negative in three patients without a final diagnosis of infarct (100% sensitivity, 100% specificity, chi2 = 30, P < 0.0001). Ischaemic infarcts were visible on 15 and not seen on 12 CT studies (55 % sensitivity, 100% specificity, chi2 = 1.48, P = 0.224). With regard to the single readings (30 examinations x 5 examiners = 150 readings), 63 CT readings were true positive and 72 false negative (sensitivity 47 %, specificity 86%, chi2 = 2.88, P = 0.089). Of the DWI readings 128 were true positive and 7 false negative (sensitivity 95%, specificity 87 %, chi2 = 70.67, P < 0.0001). Interobserver agreement was substantial for CT (chi = 0.72, 95 % confidence interval, 0.6-0.84) and DWI (chi = 0.82, 95 % confidence interval, 0.46-1). Taken together, detectability and detection rate of acute (< 6 h) hemisphere infarcts are significantly higher with DWI than with CT.

Long term outcome after transjugular intrahepatic portosystemic stent-shunt in non-transplant cirrhotics with hepatorenal syndrome: a phase II study

BACKGROUND

Recent small studies on hepatorenal syndrome (HRS) indicate some clinical benefit after transjugular intrahepatic portosystemic stent-shunt (TIPS) but sufficient long term data are lacking.

AIM

We studied prospectively feasibility, safety, and long term survival after TIPS in 41 non-transplantable cirrhotics with HRS (phase II study).

PATIENTS AND METHODS

HRS was diagnosed using current criteria (severe (type I) HRS, n=21; moderate (type II) HRS, n=20). Thirty one patients (14 type I, 17 type II) received TIPS (8-10 mm) while advanced liver failure excluded shunting in 10. During follow up (median 24 months) we analysed renal function and survival (Kaplan-Meier).

RESULTS

TIPS markedly reduced the portal pressure gradient (21 (5) to 13 (4) mm Hg (mean (SD)); p<0.001) with one procedure related death (3.2%). Renal function deteriorated without TIPS but improved (p<0.001) within two weeks after TIPS (creatinine clearance 18 (15) to 48 (42) ml/min; sodium excretion 9 (16) to 77 (78) mmol/24 hours) and stabilised thereafter. Following TIPS, three, six, 12, and 18 month survival rates were 81%, 71%, 48%, and 35%, respectively. As only 10% of non-shunted patients survived three months, total survival rates were 63%, 56%, 39%, and 29%, respectively. Multivariate Cox regression analysis revealed bilirubin (p<0.001) and HRS type (p<0.05) as independent survival predictors after TIPS.

CONCLUSIONS

TIPS provides long term renal function and probably survival benefits in the majority of non-transplantable cirrhotics with HRS. These data warrant controlled trials evaluating TIPS in the management of HRS.

Middle cerebral artery (MCA) susceptibility sign at susceptibility-based perfusion MR imaging: clinical importance and comparison with hyperdense MCA sign at CT

PURPOSE

To describe the radiologic findings of susceptibility changes in acute middle cerebral artery (MCA) thromboembolism detected with three-dimensional (3D) susceptibility-based perfusion magnetic resonance (MR) imaging and to compare the detectability and clinical value of this sign with those of the hyperdense MCA sign at computed tomography (CT).

MATERIALS AND METHODS

Twenty-three patients (mean age, 55 years) underwent CT and MR imaging within the first 6 hours after the onset of acute MCA stroke. The hyperdense MCA sign at CT and the presence of susceptibility changes in acute thromboembolism as depicted on T2*-weighted 3D perfusion MR images were assessed. The presence of each sign was correlated with clinical presentation.

RESULTS

The sensitivity of the hyperdense MCA sign at CT was 54% (negative predictive value, 71%) compared with 82% (negative predictive value, 86%) for the susceptibility changes at MR imaging. There were no false-positive CT or MR readings. The presence of the MCA susceptibility sign correlated positively with the initial clinical presentation (chi(2) = 7.987, P =.009, Spearman rho = 0.589). However, neither of the signs was a predictor for clinical outcome in cases of spontaneous MCA stroke.

CONCLUSION

In addition to the information traditionally provided with reconstructed perfusion parameter maps, 3D susceptibility-based perfusion MR images allow the identification of acute MCA thromboembolism with a sensitivity higher than that of CT.

[CT angiography hemodynamically relevant to renal artery stenosis. Evaluation of AXIAL, MPR, MIP and SSD reconstruction procedures under standard investigation conditions]

PURPOSE

To evaluate the various reconstruction methods of helical-CT angiography for the assessment of hemodynamically relevant renal artery stenoses in comparison to i.a. DSA.

METHODS

In 76 renal arteries the reconstruction modalities AXIAL, MRP, MIP and SSD of helical-CT angiography were compared with the results of i.a. DSA for the determination of the grade and location of the stenosis.

RESULTS

The highest accuracy of stenosis grading was 76% with AXIAL reconstruction. In 8% of the cases grading of the stenosis was not evaluable by the AXIAL reconstruction. In these cases, a higher sensitivity in the detection of hemodynamically relevant stenoses (> grade II, > 50%) was achieved with the reconstruction mode MPR (96%) than with MIP (92%). In 51% of the cases the reconstruction mode SSD was not suitable for any diagnosis of renal artery stenosis because of overlying calcified plaques.

CONCLUSIONS

The evidence of hemodynamically relevant stenosis in helical-CT angiography in comparison to i.a. DSA succeeds most reliable by using the reconstruction modality AXIAL in combination with MPR. The MIP reconstruction provides information about the anatomy of the renal arteries within one image.

Infantile fibromatosis of the neck with intracranial involvement: MR and CT findings

CT and MR imaging studies were performed in a 3-year-old boy with infantile fibromatosis arising from the infratemporal fossa and extending into the middle cranial fossa. On CT scans, the lesion was hyperattenuating (44-49 Hounsfield units [HU]), enhancing significantly after application of contrast material (63-66 HU). The MR images showed a multilobulated lesion of heterogeneous signal intensity. The tumor was markedly hypointense on T2-weighted images and slightly hypointense on T1-weighted images relative to brain tissue, iso- or slightly hyperintense relative to tongue muscle on both T2- and T1-weighted images, and enhanced strongly after administration of gadopentetate dimeglumine.

Surgery for portal hypertension and transjugular intrahepatic portosystemic shunts in Germany: results of a national survey

A national survey was conducted to determine the role of portosystemic shunt surgery and transjugular intrahepatic portosystemic shunt (TIPS) in Germany. A questionnaire was mailed to 1324 surgical units at 1273 hospitals, and 941 responses (74%) were received. Interventional endoscopy for variceal bleeding is carried out predominantly (73%) in medical departments. From 1992 to 1997 the annual number of surgical shunts dropped from 253 to 120, whereas the respective numbers of TIPS increased from 202 to 920. In this 6-year period a total of 1042 shunts and 3575 TIPS were reported by 109 and 64 centers, respectively. TIPS was applied mainly in university hospitals (88.9%), whereas shunt surgery was more broadly used in non-university hospitals (58.8%). Clearly, prospective randomized comparisons of TIPS and surgical shunts are needed to reveal which treatment is best in patients with variceal bleeding stratified for mortality risk and stage of liver disease. However, the decreasing number and experience with shunt surgery may impede such studies. Probably, liver transplant centers which currently do only 41.2% of shunt procedures are most familiar with surgery in portal hypertension and are therefore most appropriate to maintain quality and expertise in this palliative and demanding branch of surgery.

[The MRT of focal liver lesions: the value of gadolinium-enhanced dynamic studies of the whole organ with a fast 3D-turbo-gradient echo sequence]

PURPOSE

To determine the value of a dynamic Gd-enhanced ultrafast T1-weighted 3D-turbo-gradient-echo sequence (3D-TFE) in the detection and characterization of focal liver lesions.

MATERIALS AND METHODS

51 patients with 124 focal liver lesions (35 hemangiomas, 30 HCC, 24 metastases, 22 cysts, 5 FNH/adenoma, 8 other lesions) were examined using a 1.5 T system. The dynamic 3D-TFE sequence, achieving 40 slices with a thickness of 4.5 mm in a 17-s breath-hold, was compared with a fat-suppressed T2-weighted fast-spin-echo sequence (TSE SPIR), unenhanced and Gd-enhanced T1-weighted spin-echo sequences (SE), and a T1-weighted gradient-echo sequence (FFE).

RESULTS

On 3D-TFE images more lesions (107/124) were identified than on T1-weighted SE (101/124) and T1-weighted FFE images (106/124), but less compared to T2-weighted TSE SPIR images (115/124). The 3D-TFE-sequence provided additional information in 65/107 (61%) detected lesions by delineating the dynamic enhancement pattern, most valuable in patients with HCCs in 90%.

CONCLUSIONS

On dynamic 3D-TFE images more lesions could be depicted than on conventional T1-weighted SE and T1-weighted FFE images. Visualization of the dynamic enhancement pattern provided additional information for tumor characterization in 61% of the detected lesions on the 3D-TFE images.

[MRI diagnosis of cardiac myxomas: sequence evaluation and differential diagnosis]

PURPOSE

To evaluate native and contrast enhanced T1-weighted spin (T1-SE), cine gradient echo (Cine-GE), and T2-weighted turbo spin (T2-TSE) sequences in the diagnosis and differential diagnosis of cardiac myxomas.

METHODS

15 patients with echocardiographically suspected cardiac atrial myxomas underwent 0.5 T-MR imaging of the heart with native T1-SE, contrast-enhanced T1-SE, Cine-GE, and T2-TSE sequences. MR images were evaluated for signal intensity (SI) and lesion's conspicuity. Results were confirmed histologically (14 x) or by follow-up (1 x).

RESULTS

MRI revealed myxomas in 9 patients, sarcomas in three patients, and thrombi in three patients. Lesion conspicuity was better in Cine-GE and T2-TSE compared with native and contrast-enhanced T1-SE sequences. Myxomas were characterized by an intermediate SI similar to myocardium in T1-SE, high SI similar to water in T2-TSE, and low to moderately high enhancement (range 19-75%, mean 48%).

CONCLUSION

Distinct SI characteristics together with anatomical-topographical features (attachment to the interatrial septum, no infiltration of myocardium and vessels) are diagnostic for cardiac myxomas. Cine-GE and T2-TSE sequences are the sequences of choice for detection of myxomas and other atrial masses. T2-TSE and contrast-enhanced T1-weighted sequences are most useful for mass characterisation and differentiation between myxomas, malignant tumors, and thrombi.

[Independent radiologic prognostic factors for fatal outcome of ambulatory-acquired pneumonia requiring inpatient treatment]

PURPOSE

To evaluate the independent prognostic impact of the chest radiograph for mortality from community-acquired pneumonia requiring hospitalization.

METHODS

Chest radiographs of 67 patients with hospital-treated community-acquired pneumonia were analyzed with regard to the prognostic implications of radiographic patterns, extent and density of infiltrates, and its evolution during treatment.

RESULTS

Non-survivors had a significantly higher extent of infiltrates (p = 0.008), density of infiltrates (p = 0.05), and radiographic spread during follow-up within 48-75 hours (p = 0.0001). In multivariate analysis, persistent or progressive infiltrates were associated with a 47-fold increase, and persistent or progressive density of infiltrates with an 18-fold increase in risk of mortality. The presence of both parameters could correctly predict 96% of survivors and 90% of non-survivors.

CONCLUSIONS

The chest radiograph is an independent predictor of the severity of pneumonia. Both persistent or progressive infiltrates and persistent or progressive density of infiltrates are independently associated with mortality from community-acquired pneumonia.

[Variants of the hepatic artery: detection with color--coded sonography pre and post levovist injection]

PURPOSE

Detection of hepatic artery variants is of great clinical importance, for instance, pre liver transplantation, pre intraarterial chemotherapy or for measurement of the Doppler perfusion index. We therefore investigated how accurate variants of the hepatic artery can be detected using color-coded sonography pre and post Levovist injection.

MATERIALS AND METHODS

52 patients (21-78 years) were examined using color-coded sonography pre and post Levovist injection. After the sonographic examination, intraarterial digital subtraction angiography was performed and the results were compared.

RESULTS

Using angiography 14 variants of the hepatic artery were detected in 13 patients. The most common variant in 10 patients were hepatic arteries originating from the superior mesenteric artery. This could be detected with unenhanced color-coded sonography in 8 and with enhanced sonography in 9 patients. In one patient in addition, a hepatogastric trunk was noted by angiography, this was not recognized by sonography. In 2 patients with a hepatogastric trunk, this variant was sonographically seen after Levovist injection in both but with unenhanced sonography in only 1 patient.

CONCLUSION

Most variants of the arterial hepatic blood supply can be diagnosed using conventional color-coded sonography. In some cases enhanced sonography provides additional information, but even with these techniques all variations cannot be detected.

[MRI diagnosis in longitudinal stress fractures: differential diagnosis of Ewing sarcoma]

PURPOSE

To compare MR imaging features of stress fractures, simulating malignancies, and Ewing sarcomas.

MATERIALS AND METHODS

MR imaging studies of 4 patients with longitudinal stress fractures of the tibia (n = 2) and the femur (n = 2) simulating malignancy were retrospectively compared with the MRI scans of 10 patients with histologically proven Ewing sarcoma (femur n = 5; tibia n = 3, fibula n = 1, humerus n = 1). The diagnosis of stress fractures was confirmed by follow-up examinations. An additional biopsy was performed in two patients.

RESULTS

Despite negative x-ray examinations, MRI showed the fracture line in all patients with stress fractures. In these cases marrow edema was irregular and there was no well defined margin towards normal fatty marrow. In contrast Ewing sarcomas were sharply demarcated in 9/10 cases. Extraosseous enhancing soft tissue was found in Ewing sarcomas as well as in stress fractures. In stress fractures the enhancing mass was repair tissue. Areas of necrosis within the enhancing mass was seen in (8/10) Ewing sarcomas, only. In follow-up studies we observed a decrease of the marrow edema in patients with stress fractures. Occurrence of low signal areas in T1- and T2-weighted sequences within the initial enhanced extraosseous tissue corresponded to bony callus on x-rays films.

CONCLUSIONS

Repair tissue in stress fractures can imitate malignancy. The irregularity of the marrow edema without well defined margins, the lack of necrosis in the small enhancing tissue and the proof of the fracture line in the MRI are criteria to differentiate stress fractures from Ewing sarcomas. Short-term follow up studies are helpful to underline the diagnosis.

[Non-aortic extracranial arterial aneurysm]

Aortic and intracranial arterial aneurysms constitute frequent clinical entities for which sophisticated vascular surgical and interventional radiological therapeutic procedures have been established. To a much lesser extent arterial aneurysms can also occur at any other vascular site due to a large number of possible reasons. In this article we conducted a Medline search of the world literature for reports on these rare vascular disorders and summarize the most important clinical aspects on this subject. Altogether 5535 cases of non-aortic extracranial aneurysms are reviewed.

Endoscopic manometry of esophageal varices: evaluation of a balloon technique compared with direct portal pressure measurement

BACKGROUND/AIMS

Recently, a non-invasive endoscopic balloon technique for esophageal manometry was published. In the present study, we assess its methodological aspects together with the relationship to portal pressure.

METHODS

In 20 patients with liver cirrhosis who had received an intrahepatic portosystemic stent-shunt (TIPS), we evaluated portal and variceal pressure before and after balloon occlusion of TIPS (random order). Portal pressure was measured continuously via a portal venous catheter, and variceal pressure was determined at the same time independently by two endoscopists using two balloon techniques (inflation until varix collapses; deflation until varix reappears).

RESULTS

Overall, mean (+/-SD) portal pressure (28.5+/-7 mmHg) was significantly higher (p<0.001) than mean variceal pressure (24.4+/-6 mmHg). Balloon manometry-determined variceal pressure values were 10+/-15% higher with the inflation technique (26.2+/-7 mmHg) than with the balloon deflation technique (22.6+/-6 mmHg, p<0.001). Portal pressure and variceal pressure correlated significantly (p<0.001; balloon inflation: r=0.61, balloon deflation: r=0.66, mean values of inflation and deflation: r=0.68). Short-term TIPS occlusion led to mean increases of 52% and 35% in portal pressure and variceal pressure, respectively. The manometry results of both endoscopists correlated well with either balloon technique (r> or =0.93; p<0.001) and we saw no adverse effects.

CONCLUSIONS

Variceal balloon manometry provides non-invasive variceal pressure data which correlate to portal pressure assessed prior to and after short-term TIPS occlusion. However, probably due to variance in collateral anatomy, variceal pressure does not exactly predict portal pressure and its acute changes in the individual patient. The averaged variceal pressure of the inflation and deflation balloon technique provides the best relation to portal pressure combined with a good interobserver reliability and warrants further clinical evaluation.

[Evaluation of the effects of bioadhesive substances as addition to oral contrast media: an experimental study]

PURPOSE

To evaluate the additional effect of bioadhesives in combination with iotrolan and barium as oral contrast media in an animal model.

METHOD

The bioadhesives Noveon, CMC, Tylose and Carbopol 934 were added to iotrolan and barium. The solutions were administered to rabbits by a feeding tube. The animals were investigated by computed tomography (CT) and radiography after 0.5, 4, 12, 24 and in part after 48 hours. Mucosal coating and contrast filling of the bowel were evaluated.

RESULTS

Addition of bioadhesives to oral contrast media effected long-term contrast in the small intestine and colon, but no improvement in continuous filling and coating of the gastrointestinal tract was detected. Mucosal coating was seen only in short regions of the caecum and small intestine. In CT the best results for coating were observed with tylose and CMC, in radiography additionally with carbopol and noveon. All contrast medium were well tolerated.

CONCLUSION

The evaluated contrast medium solutions with bioadhesives have shown long-term contrast but no improvement in coating in comparison to conventional oral contrast media.

[Improved diagnosis of early cerebral infarct by the combined use of diffusion and perfusion]

PURPOSE

To evaluate the feasibility and the diagnostic efficacy of multislice diffusion-weighted and perfusion imaging in addition to FLAIR-TSE, T2w-GraSE and MR-angiography in the diagnosis of acute stroke.

METHODS

18 patients with acute stroke were examined at 1.5 Tesla (Gyroscan ACS-NT, Philips Medical Systems) within 6 (n = 9) and 6-48 (n = 9) hours, respectively, and followed at regular intervals. For diffusion imaging we used a multislice multishot EPI-SE sequence with navigator echo correction and cardiac gating. Perfusion imaging was done by means of a FFE-EPI sequence after bolus injection of Gd-DTPA.

RESULTS

The diagnostic value of diffusion-weighted and perfusion imaging was significantly higher compared with FLAIR-TSE (p = 0.0023) and GraSE (p = 0.0012) during the first 6 hours. With FLAIR-TSE and GraSE first pathologic changes were seen after 4 hours. We detected perfusion deficit (rCBV < 10%) and a corresponding drop of the ADC in all infarcts larger than 1 cm in diameter. Within the area of low rCBV the combined analysis of diffusion and perfusion imaging allows to identify an infarct region with characteristics of a penumbra and one with characteristics of the infarct core. TTP was increased in the surrounding tissue. However, parts of this area were rarely included in the infarct. The final extension of the untreated infarct, as revealed by computed tomography, corresponded well to the perfusion deficit.

CONCLUSIONS

Early ischaemic cerebral infarcts can be diagnosed with diffusion and perfusion imaging before pathological changes are visualized with other imaging modalities. The combined use may allow to distinguish the infarct core from surrounding, potentially salvageable tissue.

Indirect MR arthrography: techniques and applications

Indirect MR arthrography is a relatively new MR technique improving articular and periarticular contrast. It is achieved by injection of paramagnetic MR contrast media intravenously instead of intra-articular injection as in direct MR arthrography. After the injection exercising the joint results in considerable signal intensity increase within the joint cavity. Fat saturated MR sequences then yield arthrographic images. The method is less invasive than direct MR arthrography and first results showed comparable sensitivities and specificities for rotator cuff and glenoid labrum pathology. In this article the technique, established and potential future indications, drawbacks and limitations of the method are reviewed.

[Native and signal-enhanced power Doppler sonography for characterization of liver lesions]

PURPOSE

To evaluate the characterisation of liver lesions using power Doppler sonography before and after intravenous injection of the ultrasound contrast agent Levovist.

MATERIALS AND METHODS

39 patients with 41 liver lesions (10 haemangiomas, 2 focal nodular hyperplasias (FNH), 2 focal fatty infiltrations, 1 echinococcal lesion, 11 hepatocellular carcinomas, 14 metastases and one cholangiocarcinoma) were evaluated prospectively. Power Doppler images before and after intravenous injection of the ultrasound contrast agent Levovist were analysed by two radiologists and one gastroeterologist, who subjectively classified the distribution (peripheral, central, diffuse) and amount (none, minimal, moderate and strong) of flow pattern in each sonographic examination. Histological verification was obtained in all liver lesions, except in haemangiomas, where MR imaging and in one FNH where scintigraphy was regarded as sufficient proof.

RESULTS

On the whole, power Doppler sonography after contrast injection was superior to unenhanced power Doppler-sonography in 20 liver lesions and equal in 7. After contrast injection, previously visible flow was enhanced in 14 patients, in 6 lesions flow was detected, which was not seen before in the power mode. Moderate or strong flow signals were detected before contrast injection in 8/26, post contrast injection in 18/26 malignant tumours. Contrawise, 13/15 benign lesions did show any or only minimal flow signals before and 10/15 after contrast injection.

CONCLUSION

Intratumoural flow signals favour a malignant tumour. The absence of flow signals is a frequent finding in benign lesions but does not rule out malignancy.

[Radiation exposure of radiation-sensitive risk organs--ocular lens, parotid gland, thyroid gland--in dacryocystography and therapy]

PURPOSE

Evaluation of radiation dose to the radiosensitive head and neck organs and tissues-ocular lens, parotid and thyroid glands--during dacryocystography and fluoroscopy--guided dacryocystoplasty (DCP).

METHOD

Radiation dose was determined in an Alderson Rando phantom and in 13 patients. Radiation dose was measured directly using Ca-F2-thermoluminescent dosimetry crystals (TLD) which were placed on each eyelid, parotid gland and thyroid gland.

RESULTS

The mean radiation dose to the lens placed next to the path of radiation was 6.58 mGy in the Alderson-Rando phantom and 5.43 mGy in patients during DCP. The mean radiation dose to the contralateral lens was 1.37 mGy and 1.7 mGy to the parotid gland placed next to the x-ray tube. Radiation dose to the thyroid gland was max. 0.4 mGy during DCP.

CONCLUSION

Radiation dose to the ocular lens, parotid gland and thyroid gland during fluoroscopy-guided DCP was 25 times higher than during diagnostic dacryocystography. The radiation dose to radiosensitive head and neck organs and tissues during fluoroscopy-guided DCP is much below the threshold dose for ocular lens cataract.

[MR relaxation time measurements with and without selective fat suppression (SPIR) in endocrine orbitopathy]

PURPOSE

To determine the value and utility of relaxation time measurements with magnetic resonance (MR) imaging in patients with Graves' ophthalmopathy (G.O.).

MATERIALS AND METHODS

20 orbits were studied in control subjects and 58 orbits in patients with G.O. T2 relaxation times of extraocular muscles and retrobulbar fat tissue were calculated. The thickness of the eye muscles was correlated with the calculated T2 times. 18 orbits were measured before and after retro-orbital radiation therapy.

RESULTS

Upper limits of determined normal T2 values were 60 ms in extraocular eye muscles and 40 ms in retrobulbar fat tissue. 89% (17/19) of the patients with G.O. had prolonged T2 times in extraocular eye muscles. The retrobulbar fat tissue in 5 of 38 orbits revealed minimal edema with the use of fat saturated sequences. T2 relaxation times decreased significantly (p < 10(-4)) after 10 Gy radiation therapy. No correlation was found between enlargement and T2 relaxation times in extraocular eye muscles (r = 0.44 in patients before radiation therapy).

CONCLUSION

In patients with G.O. the determination of the enlargement of extraocular eye muscles in computed tomography is not a sufficient parameter for an antiinflammatory therapy, since CT cannot visualise eye muscle edema. T2 relaxation time measurements with MR imaging allow differentiation between edematous and fibrotic changes. This is the diagnostic method of choice in patients with Graves' ophthalmopathy.

[Craniocervical dissections: study strategies in MR imaging and MR angiography]

PURPOSE

To define the diagnostic efficacy of MR imaging, "time of flight" (TOF) and phase contrast (PC) MR angiography in craniocervical arterial dissections.

MATERIAL AND METHODS

The MR examinations of 16 patients with proven arterial dissections (n = 20) were retrospectively analysed by three independent readers. The MR protocol included T1w spin echo sequences with and without fat saturation (SPIR), T2w-turbo-spin echo, 2D- and 3D-TOF- and 3D-PC-MRA. The study was undertaken to assess the diagnostic sensitivity of each technique in detecting typical pathological features.

RESULTS

The overall sensitivity was best in 3D-PC-MRA; reaching 88% of all possible points. Intramural haematoma could be easily detected with T1W spin echo with fat saturation (100%). Intimal flap and lumen narrowing was best defined with 3D-TOF-MRA in 86% resp. 96% and 3D-PC-MRA in 69% resp. 97%. 3D-PC-MRA was superior to all other sequences in 5 cases of aneurysmal dissection (100%).

CONCLUSIONS

An accurate evaluation of craniocervical arterial dissections should rely on a combined protocol including T1w spin echo with fat saturation and an axial 3D-MR angiography (if possible 3D-phase contrast MRA).