Coronary MR imaging: lumen and wall.

Coronary MR imaging is a promising noninvasive technique for the combined assessment of coronary artery anatomy and function. Anomalous coronary arteries and aneurysms can reliably be assessed in clinical practice using coronary MR imaging and the presence of significant left main or proximal multivessel coronary artery disease detected. Technical challenges that need to be addressed are further improvements in motion suppression and abbreviated scanning times aimed at improving spatial resolution and patient comfort. The development of new and specific contrast agents, high-field MR imaging with improved spatial resolution, and continued progress in MR imaging methods development will undoubtedly lead to further progress toward the noninvasive and comprehensive assessment of coronary atherosclerotic disease.

Cost evaluation of cardiac magnetic resonance imaging versus coronary angiography for the work-up of coronary artery disease

Background: CMR has recently emerged as a robust and reliable technique to assess coronary artery disease (CAD). A negative perfusion CMR test predicts low event rates of 0.3-0.5%/year. Invasive coronary angiography (CA) remains the "gold standard" for the evaluation of CAD in many countries.Objective: Assessing the costs of the two strategies in the European CMR registry for the work-up of known or suspected CAD from a health care payer perspective. Strategy 1) a CA to all patients or 2) a CA only to patients who are diagnosed positive for ischemia in a prior CMR.Method and results: Using data of the European CMR registry (20 hospitals, 11'040 consecutive patients) we calculated the proportion of patients who were diagnosed positive (20.6%), uncertain (6.5%), and negative (72.9%) after the CMR test in patients with known or suspected CAD (n=2'717). No other medical test was performed to patients who were negative for ischemia. Positive diagnosed patients had a coronary angiography. Those with uncertain diagnosis had additional tests (84.7%: stress echocardiography, 13.1%: CCT, 2.3% SPECT), these costs were added to the CMR strategy costs. Information from costs for tests in Germany and Switzerland were used. A sensibility analysis was performed for inpatient CA. For costs see figure. Results - costs.Discussion: The CMR strategy costs less than the CA strategy for the health insurance systems both, in Germany and Switzerland. While lower in costs, the CMR strategy is a non-invasive one, does not expose to radiation, and yields additional information on cardiac function, viability, valves, and great vessels. Developing the use of CMR instead of CA might imply some reduction in costs together with superior patient safety and comfort, and a better utilization of resources at the hospital level. Document introduit le : 01.12.2011

Noninvasive detection of macrophage-rich atherosclerotic plaque in hyperlipidemic rabbits using "positive contrast" magnetic resonance imaging.

OBJECTIVES: This study was designed to identify macrophage-rich atherosclerotic plaque noninvasively by imaging the tissue uptake of long-circulating superparamagnetic nanoparticles with a positive contrast off-resonance imaging sequence (inversion recovery with ON-resonant water suppression [IRON]). BACKGROUND: The sudden rupture of macrophage-rich atherosclerotic plaques can trigger the formation of an occlusive thrombus in coronary vessels, resulting in acute myocardial infarction. Therefore, a noninvasive technique that can identify macrophage-rich plaques and thereby assist with risk stratification of patients with atherosclerosis would be of great potential clinical utility. METHODS: Experiments were conducted on a clinical 3-T magnetic resonance imaging (MRI) scanner in 7 heritable hyperlipidemic and 4 control rabbits. Monocrystalline iron-oxide nanoparticles (MION)-47 were administrated intravenously (2 doses of 250 mumol Fe/kg), and animals underwent serial IRON-MRI before injection of the nanoparticles and serially after 1, 3, and 6 days. RESULTS: After administration of MION-47, a striking signal enhancement was found in areas of plaque only in hyperlipidemic rabbits. The magnitude of enhancement on magnetic resonance images had a high correlation with the number of macrophages determined by histology (p < 0.001) and allowed for the detection of macrophage-rich plaque with high accuracy (area under the curve: 0.92, SE: 0.04, 95% confidence interval: 0.84 to 0.96, p < 0.001). No significant signal enhancement was measured in remote areas without plaque by histology and in control rabbits without atherosclerosis. CONCLUSIONS: Using IRON-MRI in conjunction with superparamagnetic nanoparticles is a promising approach for the noninvasive evaluation of macrophage-rich, vulnerable plaques.

"In vivo" imaging of atherosclerosis

Atherosclerosis is a systemic and multifocal disease, which starts early in life, and that usually takes decades before overt disease eventually appears as a consequence of progressive obstruction or abrupt thrombotic occlusion. This silent course makes necessary to develop predictors of disease long before symptomatic lesions develop. Besides several classical risk factors and new emerging humoral risk predictors, imaging may constitute a formidable diagnostic and prognostic tool in order to identify presence, extension, progression (or regression) of disease as well as vulnerability of atherosclerotic lesions. This review summarizes the rapidly growing clinical and research field in imaging atherosclerosis from different perspectives opening important opportunities for timely detection and treatment of atherosclerosis.

Life-threatening versus non-life-threatening manual strangulation: are there appropriate criteria for MR imaging of the neck?

The aim of the study was to determine objective radiological signs of danger to life in survivors of manual strangulation and to establish a radiological scoring system for the differentiation between life-threatening and non-life-threatening strangulation by dividing the cross section of the neck into three zones (superficial, middle and deep zone). Forensic pathologists classified 56 survivors of strangulation into life-threatening and non-life-threatening cases by history and clinical examination alone, and two blinded radiologists evaluated the MRIs of the neck. In 15 cases, strangulation was life-threatening (27%), compared with 41 cases in which strangulation was non-life-threatening (73%). The best radiological signs on MRI to differentiate between the two groups were intramuscular haemorrhage/oedema, swelling of platysma and intracutaneous bleeding (all p = 0.02) followed by subcutaneous bleeding (p = 0.034) and haemorrhagic lymph nodes (p = 0.04), all indicating life-threatening strangulation. The radiological scoring system showed a sensitivity and specificity of approximately 70% for life-threatening strangulation, when at least two neck zones were affected. MRI is not only helpful in assessing the severity of strangulation, but is also an excellent documentation tool that is even admissible in court.

Imaging of Lemierre Syndrome in children and young adultsA case-series analysis

Background / Purpose : Lemierre Syndrome (LS) is defined by a recent oro-pharangeal infection, the clinical presence or radiological demonstration of internal jugular vein (IJV) thrombosis and documented anaerobe germ, principally Fusobacterium necrophorum (Fn) leading to septicaemia and septic embolization. It is a rare infection described since 1900 and it nearly disappeared since the beginning of the antibiotic area. Even if it is seldom described in the literature, this infection is reappearing in the last 10 years, either because of the increase of antibiotic resistance or by modification of antibiotic prescription. The aim of this study is to describe the role of medical imaging in the diagnosis, staging and follow up of Lemierre syndrome, as well as to describe the ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI) findings of this rare disease. Patients and methods : Radiological and medical files of patients diagnosed with Lemierre syndrome in the past 6 years at CHUV hospital were analysed retrospectively. The CT scan, US, colour Doppler US (CDUS) and MRI examinations that were performed have been examined so as to define their specific imaging findings. Results IJV thrombosis was demonstrated in 2 cases by US, by CT in 6 cases and MRI in one case. Septic pulmonary emboli were detected by CT in 5 patients. Complications of the LS were depicted by MR in one case and by CT in 1 case. Conclusion : In the appropriate clinical settings, US, CT or MR evidence of IJV thrombosis and chest CT suggestive of septic emboli, should lead the physician to consider the diagnosis of LS. As a consequence, imaging allows a faster diagnosis and a more efficient treatment of this infection, which in case of insufficient therapy can lead to death.

Delineating Dementia with Lewy Bodies: Can Magnetic Resonance Imaging Help?

As future treatments increasingly target the protein chemistry underlying the different dementias, itbecomes crucially important to distinguish between the dementias during life. Neither specific proteinnor genetic markers are as yet available in clinical practice. However, neuroimaging is an obviouscandidate technique that may yield enhanced diagnostic accuracy when applied to thedementias. The physiopathology and anatomopathology is complex in dementia with Lewy bodies(DLB). Besides the relative sparing of medial temporal lobe structures in DLB in comparison toAlzheimer's disease, no clear signature pattern of cerebral atrophy associated with DLB has beenestablished so far. Among others, one reason may be the difficulty in visualizing the small brainnuclei that are differentially involved among the dementias. While we think that structural magneticresonance imaging neuroimaging should be part of the diagnostic workup of most dementia syndromesdue to its usefulness in the differential diagnosis, its contribution to a positive diagnosis ofDLB is as yet limited. The development of different neuroimaging techniques may help distinguishreliably DLB from other neurodegenerative disorders. However, in order to become accepted as partof standard care, these techniques must still prove their effectiveness under routine conditions suchas those encountered by the general practitioner.

Diffusion spectrum imaging shows the structural basis of functional cerebellar circuits in the human cerebellum in vivo.

BACKGROUND: The cerebellum is a complex structure that can be affected by several congenital and acquired diseases leading to alteration of its function and neuronal circuits. Identifying the structural bases of cerebellar neuronal networks in humans in vivo may provide biomarkers for diagnosis and management of cerebellar diseases. OBJECTIVES: To define the anatomy of intrinsic and extrinsic cerebellar circuits using high-angular resolution diffusion spectrum imaging (DSI). METHODS: We acquired high-resolution structural MRI and DSI of the cerebellum in four healthy female subjects at 3T. DSI tractography based on a streamline algorithm was performed to identify the circuits connecting the cerebellar cortex with the deep cerebellar nuclei, selected brainstem nuclei, and the thalamus. RESULTS: Using in-vivo DSI in humans we were able to demonstrate the structure of the following cerebellar neuronal circuits: (1) connections of the inferior olivary nucleus with the cerebellar cortex, and with the deep cerebellar nuclei (2) connections between the cerebellar cortex and the deep cerebellar nuclei, (3) connections of the deep cerebellar nuclei conveyed in the superior (SCP), middle (MCP) and inferior (ICP) cerebellar peduncles, (4) complex intersections of fibers in the SCP, MCP and ICP, and (5) connections between the deep cerebellar nuclei and the red nucleus and the thalamus. CONCLUSION: For the first time, we show that DSI tractography in humans in vivo is capable of revealing the structural bases of complex cerebellar networks. DSI thus appears to be a promising imaging method for characterizing anatomical disruptions that occur in cerebellar diseases, and for monitoring response to therapeutic interventions.

Well-differentiated papillary mesothelioma of the tunica vaginalis testis: imaging on Tc-99m heat-denatured red blood cell scintigraphy.

An 18-year-old man presented with a growing painless left scrotal mass. Sonography showed a hydrocele and a homogeneous, well-encapsulated left extratesticular mass with similar echogenicity as the normal testis, suggestive of a splenogonadal fusion. To substantiate the diagnosis, the patient underwent Tc-99m heat-denatured red blood cell scintigraphy showing normal physiological hyperactivity in the spleen but activity similar to the blood pool projecting on the upper part of the left testis. This made testicular splenic tissue less likely. The patient underwent resection and histopathology revealed a well-differentiated papillary mesothelioma. Inguinal orchidectomy was subsequently performed and the patient was free of recurrence at 18 months.

Towards the utilization of EEG as a brain imaging tool.

Recent advances in signal analysis have engendered EEG with the status of a true brain mapping and brain imaging method capable of providing spatio-temporal information regarding brain (dys)function. Because of the increasing interest in the temporal dynamics of brain networks, and because of the straightforward compatibility of the EEG with other brain imaging techniques, EEG is increasingly used in the neuroimaging community. However, the full capability of EEG is highly underestimated. Many combined EEG-fMRI studies use the EEG only as a spike-counter or an oscilloscope. Many cognitive and clinical EEG studies use the EEG still in its traditional way and analyze grapho-elements at certain electrodes and latencies. We here show that this way of using the EEG is not only dangerous because it leads to misinterpretations, but it is also largely ignoring the spatial aspects of the signals. In fact, EEG primarily measures the electric potential field at the scalp surface in the same way as MEG measures the magnetic field. By properly sampling and correctly analyzing this electric field, EEG can provide reliable information about the neuronal activity in the brain and the temporal dynamics of this activity in the millisecond range. This review explains some of these analysis methods and illustrates their potential in clinical and experimental applications.

Respiratory motion artifact suppression in diffusion-weighted MR imaging of the spine.

Diffusion-weighted spin-echo imaging of the spine has been successfully implemented for differentiation of benign fracture edema and tumor infiltration of the vertebral body. Nevertheless, this technique still suffers from insufficient image quality in numerous patients due to motion artifacts. The aim of this study was to investigate the impact of variable respiratory motion artifact suppression techniques on image quality in diffusion-weighted spin-echo imaging of the spine. In addition to phase-encoding reordering, a newly implemented right hemi-diaphragmaitc navigator for respiratory gating was used. Subjective and objective image quality parameters were compared. Respiratory motion artifact suppression has a major impact on image quality in diffusion-weighted imaging of the spine. Phase-encoding reordering does not enhance image quality while right hemi-diaphragmatic respiratory navigator gating significantly improves image quality at the cost of data acquisition time. Navigator gating should be used if standard spin-echo diffusion-weighted imaging demonstrates insufficient image quality.

The promise of advanced imaging techniques for the detection of hepatitis C virus antigens in the infected liver.

Injection drug use before and after liver transplantation: a retrospective multicenter analysis on incidence and outcome. Clin Transplant 2009 DOI: 10.1111/j.1399-0012.2009.01121.x. Background and aims: Injecting drug use (IDU) before and after liver transplantation (LT) is poorly described. The aim of this study was to quantify relapse and survival in this population and to describe the causes of mortality after LT. Methods: Past injection drug users were identified from the LT listing protocols from four centers in Switzerland and France. Data on survival and relapse were collected and used for uni- and multivariate analysis. Results: Between 1988 and 2006, we identified 59 patients with a past history of IDU. The mean age at transplantation was 42.4 yr and the majority of patients were men (84.7%). The indication for LT was for the vast majority viral cirrhosis accounting for 91.5% of cases, while alcoholic cirrhosis was 5.1%. There were 16.9% of patients who had a substitution therapy before and 6.8% who continued after LT. Two patients (3.4%) relapsed into IDU after LT and died at 18 and 41 months. The mean follow-up was 51 months. Overall survival was 84%, 66%, and 61% at 1, 5, and 10 yr after transplantation. Conclusions: Documented IDU was rare in liver transplanted patients. Past IDU was not associated with poorer survival after LT, and relapse after LT occurred in 3.4%.

High-density electric source imaging (esi) in focal epilepsy: a prospective study of 150 operated patients

Purpose: EEG is mandatory in the diagnosis of the epilepsy syndrome. However, its potential as imaging tool is still under estimated. In the present study, we aim to determine the prerequisites of maximal benefit of electric source imaging (ESI) to localize the irritative zone in patients with focal epilepsy. Methods: One hundred fifty patients suffering from focal epilepsy and with minimum 1 year postoperative follow-up were studied prospectively and blinded to the underlying diagnosis. We evaluated the influence of two important factors on sensitivity and specificity of ESI: the number of electrodes (low resolution, LR-ESI: <30 versus high resolution, HR-ESI: 128-256 electrodes), and the use of individual MRI (i-MRI) versus template MRI (t-MRI) as the head model. Findings: ESI had a sensitivity of 85% and a specificity of 87% when HR-ESI with i-MRI was used. Using LR-ESI, sensitivity decreased to 68%, or even 57% when only t-MRI was available. The sensitivity of HR-ESI/i-MRI compared favorably with those of MRI (76%), PET (69%) and ictal/interictal SPECT (64%). Interpretation: This study on a large patient group shows excellent sensitivity and specificity of ESI if 128 EEG channels or more are used for ESI and if the results are coregistered to the patient's individual MRI. Localization precision is as high as or even higher than established brain imagery techniques. HR-ESI appears to be a valuable additional imaging tool, given that larger electrode arrays are easily and rapidly applied with modern EEG equipment and that structural MRI is nearly always available for these patients.

Disagreement between ultrasound and magnetic resonance imaging in the identification of schistosomal periportal fibrosis

Abdominal ultrasound (US) has been widely used in the evaluation of patients with schistosomiasis mansoni. It represents an important indirect method of diagnosis and classification of the disease, and it has also been used as a tool in the evaluation of therapeutic response and regression of fibrosis. We describe the case of a man in whom US showed solid evidence of schistosomal periportal fibrosis and magnetic resonance imaging revealed that periportal signal alteration corresponded to adipose tissue which entered the liver togheter with the portal vein.

Early diagnosis of invasive candidiasis with mannan antigenemia and antimannan antibodies.

Late treatment of invasive candidiasis (IC) results in severe complications and high mortality. New tools are needed for early diagnosis. We conducted a retrospective study to assess the diagnostic utility of mannan antigenemia (Mn) and antimannan antibodies (anti-Mn) in neutropenic cancer patients at high risk for candidiasis. Twenty-eight patients with IC (based on European Organization for Research and Treatment of Cancer and Mycoses Study Group definitions) and 25 controls were studied. Mn and anti-Mn were positive (> or = 0.25 ng/mL and > or = 5 AU/mL, respectively) in 25/28 (89%) patients with candidiasis and in 4/25 (16%) controls: sensitivity, 89%; specificity, 84%; positive predictive value, 86%; negative predictive value, 88%. In patients with hepatosplenic lesions, assessing Mn/anti-Mn shortened the median time of diagnosis of candidiasis when compared with imaging (9 versus 25 days after fever onset as first sign of infection; P < 0.001). Candidiasis was diagnosed before neutrophil recovery in 78% and 11% of cases with Mn/anti-Mn and radiology, respectively (P < 0.001). Mn and anti-Mn may be useful for early noninvasive diagnosis of IC.