Quantification of calcium burden by coronary CT angiography compared to optical coherence tomography.

Coronary artery calcifications (CAC) are frequently observed in patients referred for coronary CT angiography (CTA). Calcification volume (in mm3) can accurately be assessed during catheterization by optical coherence tomography (OCT). The aim of the present study was to investigate the accuracy of CTA-derived assessment of calcification volume as compared with OCT. 66 calcified plaques (32 vessels) from 31 patients undergoing OCT-guided PCI with coronary CT acquired as a standard of care were included. Coronary CT and OCT images were matched using fiduciary points. Calcified plaques were reconstructed in three dimensions to calculate calcium volume. A Passing-Bablok regression analysis and the Bland-Altman method were used to assess the agreement between imaging modalities. Twenty-seven left anterior descending arteries and 5 right coronary arteries were analyzed. Median calcium volume by CTA and OCT were 18.23 mm3 [IQR 8.09, 36.48] and 10.03 mm3 [IQR 3.6, 22.88] respectively; the Passing-Bablok analysis showed a proportional without a systematic difference (Coefficient A 0.08, 95% CI - 1.37 to 1.21, Coefficient B 1.61, 95% CI 1.45 to 1.84) and the mean difference was 9.69 mm3 (LOA - 10.2 to 29.6 mm3). No differences were observed for minimal lumen area (Coefficient A 0.07, 95% CI - 0.46 to 0.15, Coefficient B 0.85, 95% CI 0.64 to 1.2). CTA volumetric calcium evaluation overestimates calcium volume by 60% compared to OCT. This may allow for an appropriate interpretation of calcific burden in the non-invasive setting. Even in presence of calcific plaques, a good agreement in the MLA assessment was found. Coronary CT may emerge as a tool to quantify calcium burden for invasive procedural planning.

The atypical antipsychotics clozapine and olanzapine promote down-regulation and display functional selectivity at human 5-HT7 receptors.

BACKGROUND AND PURPOSE: Classically, ligands of GPCRs have been classified primarily upon their affinity and efficacy to activate a signal transduction pathway. Recent reports indicate that the efficacy of a particular ligand can vary depending on the receptor-mediated response measured (e.g. activating G proteins, other downstream responses, internalization). Previously, we reported that inverse agonists induce both homo- and heterologous desensitization, similar to agonist stimulation, at the Gs -coupled 5-HT7 receptor. The primary objective of this study was to determine whether different inverse agonists at the 5-HT7 receptor also induce internalization and/or degradation of 5-HT7 receptors. EXPERIMENTAL APPROACH: HEK293 cells expressing 5-HT7(a, b or d) receptors were pre-incubated with 5-HT, clozapine, olanzapine, mesulergine or SB269970 and their effects upon receptor density, AC activity, internalization, recruitment of ß-arrestins and lysosomal trafficking were measured. KEY RESULTS: The agonist 5-HT and three out of four inverse agonists tested increased internalization independently of ß-arrestin recruitment. Among these, only the atypical antipsychotics clozapine and olanzapine promoted lysosomal sorting and reduced 5-HT7 receptor density (∼60% reduction within 24 h). Inhibition of lysosomal degradation with chloroquine blocked the clozapine- and olanzapine-induced down-regulation of 5-HT7 receptors. Incubation with SB269970 decreased both 5-HT7(b) constitutive internalization and receptor density but increased 5-HT7(d) receptor density, indicating differential ligand regulation among the 5-HT7 splice variants. CONCLUSIONS AND IMPLICATIONS: Taken together, we found that various ligands differentially activate regulatory processes governing receptor internalization and degradation in addition to signal transduction. Thus, these data extend our understanding of functional selectivity at the 5-HT7 receptor.

Primary hyperparathyroidism presenting with bilateral slipped capital femur epiphysiolysis. A pictorial essay.

It has become rare to find the typical radiological manifestations of primary hyperparathyroidism like generalized osteoporosis, brown tumors and advanced bone resorption because of the generalized usage of biochemical screening techniques. We present a 17-year-old patient with a parathyroid adenoma resulting in these typical skeletal manifestation throughout the skeleton combined with secondary bilateral slipped capital femur epiphysiolysis.

Ectopic gastric pancreatitis: unusual cause of epigastric pain.

Ectopic pancreatic tissue has the same characteristics than normal pancreatic tissue.Therefore it may be affected by the same diseases. We report a rare cause of epigastric pain due to gastric heterotopic pancreatitis.The rare diagnosis was suspected by ultrasound and CT and definitively confirmed by echo-endoscopic guided biopsies.

MDCT imaging before transcutanous aortic valve implantation: rationale and measurements.

Since its introduction in 2002, transcatheter aortic valve implantation (TAVI) has assumed growing importance in the treatment of patients with severe aortic stenosis (AS), because it offers a much less invasive alternative for those in high risk for surgery. Good early results and advances in percutaneous valve technology have led to a substantial increase in procedural success rate and number of patients undergoing this less invasive treatment. Pre-procedural screening of several anatomic factors to assess the feasibility of this technique is important. Multidetector row computed tomography (MDCT) is the technique of choice in assessing these factors.This technical note aims to describe and illustrate the key elements that need to be evaluated before the procedure.

Cost effectiveness of multi detector CT angiography of the coronary arteries for the diagnosis of suspected non-ST elevation acute coronary syndrome (NSTE-ACS) in the emergency department. Mathematical analysis with a decision model.

The purpose of our study is to model cost-effectiveness of MDCTA for the diagnosis of NSTE-ACS with initially negative enzymes, in the emergency department. In Belgium, the use of multi-detector computed tomography (MDCTA) is probably cost-effective in the diagnosis of NSTE-ACS in the acute setting A decision tree model was developed and a mathematical study was performed that included two hypothetical strategies: MDCTA and admission with classic clinical follow-up and treatment. Cost-effectiveness for the Belgian situation was simulated with sensitivity analysis using known values for diagnostic performance and known costs for the different strategies or components of strategies.

MR arthrography of the rotator cuff.

This article addresses the role of MR arthrography in the evaluation of the rotator cuff, including impingement, tendon degeneration and rotator cuff tears. Additionally, pathologic conditions of the long head of the biceps tendon, and mimickers of rotator cuff pathology are discussed as well. The drawbacks of conventional MR imaging and indirect MR arthrography, compared to the merit of direct MR arthrography are emphasized. The manuscript focusses on the potential clinical consequences of each finding and summarizes which relevant imaging findings should be reported by the radiologist.

Primary cardiac lymphoma.

Primary cardiac lymphoma is rare. It can present with a wide variability of clinical symptoms frequently leading to a delay in diagnosis. We report a case of a primary cardiac lymphoma in a 85 year old woman. The MRI showed a large mass in the right atrio-ventricular groove and infiltration of the interventricular septum and left ventricular wall with subtle contrast enhancement, isointense aspect on T1 weighted and hyperintense aspect on T2 weighted sequences. Mostly the radiological signs are non specific. Calcification, hemorrhage, a diffuse infiltrative pattern with infiltration of the valves and coronary arteries and a left atrial localization can suggest the diagnosis.

Epithelioid hemangioendothelioma of the liver: radiologic-pathologic correlation.

Epithelioid hemangioendothelioma of the liver is a rare vascular tumor with intermediate malignant potential. On imaging studies, the lesion has a solid appearance and may mimic metastatic disease. We present a case in which the morphologic features (multifocal aspect, peripheral location, and capsular retraction) and the clinical history aided in including this entity in the differential diagnosis.

Evaluation of the tetracycline- and ecdysone-inducible systems for expression of neurotransmitter receptors in mammalian cells.

Establishing a stable cell line that expresses a particular protein of interest is often a laborious and time-consuming experience. With constitutive expression systems, a gradual loss of the highly expressing clones over a given time span and/or a severe counter-selection due to toxicity of the expressed protein for the host cell line are major drawbacks. In both cases, inducible expression systems offer a valuable alternative. Over the years, many regulated expression systems have been developed and evaluated. In the present study, we compare the efficiency, the advantages and the drawbacks of a tetracycline- and an ecdysone-inducible system for expression of the reporter protein chloramphenicol acetyltransferase and of different G-protein-coupled serotonin (5-HT) receptors. A high level of expression of different 5-HT receptors was obtained with the tetracycline-inducible system. In the cell line L929, which stably expresses the tetracycline-responsive transactivator, a maximum ligand binding of 20,000 and 9500 fmol/mg protein was measured for the h5-HT(1B) and h5-ht(1F) receptors, respectively. In the HEK293rtTA cell line, levels of 15,700, 3000, and 9100 fmol bound ligand/mg protein were obtained for the h5-HT(1B), h5-ht(1F) and h5-HT(4b) receptors, respectively. These high expression levels remained stable for several months of continuous culture. Although the ecdysone-inducible expression system was useful for tightly regulated expression, the levels were far lower than those obtained with the tetracycline system (e.g. 640 fmol bound ligand/mg protein for the h5-ht(1F) receptor in HEK293EcR).

Objective pulsatile tinnitus caused by intrapetrous dissecting aneurysm.

Intrapetrosal dissections is a special kind of intracranial dissection since it is located intracranially but extradurally. Only three reports of spontaneous intrapetrosal dissection have been published so far, the posttraumatic intrapetrosal dissections caused by penetrating or blunt trauma not included. Based on the clinical and radiological presentation a treatment with anticoagulantia (a coumarine derivative) was successfully installed. A short review of the major studies concerning intracranial dissection is presented. Firm guidelines for the treatment cannot be provided based on these data but the etiology of the dissection, whether it was posttraumatic or spontaneous, seems to be important. The diagnostic problem of pulsatile tinnitus is briefly discussed.

MR imaging anatomy of the knee.

MRI of the knee joint is one of the most common and important clinical applications in most MRI units today. Thorough knowledge of the detailed anatomy is a prerequisite for the understanding of knee pathology. This article reviews the MR anatomy of menisci, the cruciate ligaments, the medial and lateral supporting structures, the extensor mechanism, synovial plicae around the joint and some pitfalls in the interpretation.