Combined PET/MRI: Global Warming-Summary Report of the 6th International Workshop on PET/MRI, March 27-29, 2017, Tübingen, Germany.

The 6th annual meeting to address key issues in positron emission tomography (PET)/magnetic resonance imaging (MRI) was held again in Tübingen, Germany, from March 27 to 29, 2017. Over three days of invited plenary lectures, round table discussions and dialogue board deliberations, participants critically assessed the current state of PET/MRI, both clinically and as a research tool, and attempted to chart future directions. The meeting addressed the use of PET/MRI and workflows in oncology, neurosciences, infection, inflammation and chronic pain syndromes, as well as deeper discussions about how best to characterise the tumour microenvironment, optimise the complementary information available from PET and MRI, and how advanced data mining and bioinformatics, as well as information from liquid biomarkers (circulating tumour cells and nucleic acids) and pathology, can be integrated to give a more complete characterisation of disease phenotype. Some issues that have dominated previous meetings, such as the accuracy of MR-based attenuation correction (AC) of the PET scan, were finally put to rest as having been adequately addressed for the majority of clinical situations. Likewise, the ability to standardise PET systems for use in multicentre trials was confirmed, thus removing a perceived barrier to larger clinical imaging trials. The meeting openly questioned whether PET/MRI should, in all cases, be used as a whole-body imaging modality or whether in many circumstances it would best be employed to give an in-depth study of previously identified disease in a single organ or region. The meeting concluded that there is still much work to be done in the integration of data from different fields and in developing a common language for all stakeholders involved. In addition, the participants advocated joint training and education for individuals who engage in routine PET/MRI. It was agreed that PET/MRI can enhance our understanding of normal and disrupted biology, and we are in a position to describe the in vivo nature of disease processes, metabolism, evolution of cancer and the monitoring of response to pharmacological interventions and therapies. As such, PET/MRI is a key to advancing medicine and patient care.

Combined PET/MRI: from Status Quo to Status Go. Summary Report of the Fifth International Workshop on PET/MR Imaging; February 15-19, 2016; Tübingen, Germany.

This article provides a collaborative perspective of the discussions and conclusions from the fifth international workshop of combined positron emission tomorgraphy (PET)/magnetic resonance imaging (MRI) that was held in Tübingen, Germany, from February 15 to 19, 2016. Specifically, we summarise the second part of the workshop made up of invited presentations from active researchers in the field of PET/MRI and associated fields augmented by round table discussions and dialogue boards with specific topics. This year, this included practical advice as to possible approaches to moving PET/MRI into clinical routine, the use of PET/MRI in brain receptor imaging, in assessing cardiovascular diseases, cancer, infection, and inflammatory diseases. To address perceived challenges still remaining to innovatively integrate PET and MRI system technologies, a dedicated round table session brought together key representatives from industry and academia who were engaged with either the conceptualisation or early adoption of hybrid PET/MRI systems. Discussions during the workshop highlighted that emerging unique applications of PET/MRI such as the ability to provide multi-parametric quantitative and visual information which will enable not only overall disease detection but also disease characterisation would eventually be regarded as compelling arguments for the adoption of PET/MR. However, as indicated by previous workshops, evidence in favour of this observation is only growing slowly, mainly due to the ongoing inability to pool data cohorts from independent trials as well as different systems and sites. The participants emphasised that moving from status quo to status go entails the need to adopt standardised imaging procedures and the readiness to act together prospectively across multiple PET/MRI sites and vendors.

Development and validation of a hybrid simulation technique for cone beam CT: application to an oral imaging system.

This paper proposes a hybrid technique to simulate the complete chain of an oral cone beam computed tomography (CBCT) system for the study of both radiation dose and image quality. The model was developed around a 3D Accuitomo 170 unit (J Morita, Japan) with a tube potential range of 60-90 kV. The Monte Carlo technique was adopted to simulate the x-ray generation, filtration and collimation. Exact dimensions of the bow-tie filter were estimated iteratively using experimentally acquired flood images. Non-flat radiation fields for different exposure settings were mediated via 'phase spaces'. Primary projection images were obtained by ray tracing at discrete energies and were fused according to the two-dimensional energy modulation templates derived from the phase space. Coarse Monte Carlo simulations were performed for scatter projections and the resulting noisy images were smoothed by Richardson-Lucy fitting. Resolution and noise characteristics of the flat panel detector were included using the measured modulation transfer function (MTF) and the noise power spectrum (NPS), respectively. The Monte Carlo dose calculation was calibrated in terms of kerma free-in-air about the isocenter, using an ionization chamber, and was subsequently validated by comparison against the measured air kerma in water at various positions of a cylindrical water phantom. The resulting dose discrepancies were found <10% for most cases. Intensity profiles of the experimentally acquired and simulated projection images of the water phantom showed comparable fractional increase over the common area as changing from a small to a large field of view, suggesting that the scatter was accurately accounted. Image validation was conducted using two small phantoms and the built-in quality assurance protocol of the system. The reconstructed simulated images showed high resemblance on contrast resolution, noise appearance and artifact pattern in comparison to experimentally acquired images, with <5% difference for voxel values of the aluminum and air insert regions and <3% difference for voxel uniformity across the homogeneous PMMA region. The detector simulation by use of the MTF and NPS data exhibited a big influence on noise and the sharpness of the resulting images. The hybrid simulation technique is flexible and has wide applicability to CBCT systems.

18FDG-Positron emission tomography for the early prediction of response in advanced soft tissue sarcoma treated with imatinib mesylate (Glivec).

Imatinib mesylate (Glivec, formerly STI571) is the first effective systemic treatment for gastrointestinal stromal tumours (GISTs). Major changes in tumour volume, however, tend to occur late after the start of treatment. The aim of this study was to evaluate if [18F]-fluorodeoxyglucose-positron emission tomography (FDG-PET) can be used for the early evaluation of response to imatinib mesylate treatment in soft-tissue sarcomas (STS). 21 patients (17 GIST, 4 other STS) underwent FDG-PET imaging prior to and 8 days after the start of treatment. PET response (European Organization for Research and Treatment (EORTC) guidelines) was observed in 13 GISTs (11 Complete Responders, 2 partial responders. Subsequent computerised tomography (CT) response Response Evaluation Criteria in Solid Tumours (RECIST) was observed in 10 of these patients after a median follow up of 8 weeks. Stable or progressive disease was observed on PET in 8 patients and none of them achieved a response on CT. PET response was also associated with a longer progression-free survival (PFS) (92% versus 12% at 1 year, P=0.00107). We conclude that FDG-PET is an early and sensitive method to evaluate an early response to imatinib treatment.

Epignathus teratoma: report of three cases with a review of the literature.

Three cases of epignathus teratoma associated with other midline anomalies are reported. The first case involved Pierre Robin sequence and a bifid tongue. The second case was characterized by two teratomas, a meningoencephalocele, and a cleft lip and nose. The third case had Pierre Robin sequence associated with duplication of the pituitary gland and hypoplasia of the corpus callosum.

FDG-PET scan in potentially operable non-small cell lung cancer: do anatometabolic PET-CT fusion images improve the localisation of regional lymph node metastases? The Leuven Lung Cancer Group.

Exact localisation of thoracic lymph nodes (LNs) on fluorine-18 fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) can be hampered by the paucity of anatomical landmarks. In non-small cell lung cancer (NSCLC) patients referred for locoregional LN staging, we prospectively examined to what extent localisation of LNs at PET reading could be improved by visual correlation with computed tomography (CT), or by anatometabolic PET+CT fusion images. Fifty-six patients with potentially operable NSCLC underwent CT, PET and surgical staging. Prospective reading was performed for CT, PET without CT, PET+CT visual correlation and PET+CT fusion. Reading was blinded to surgical pathology data and noted on a standard LN map. Surgical staging was available for 493 LN stations. In the evaluation per individual LN station, CT was accurate in 87%, PET in 91% and visual correlation and fusion in 93%. In the identification of the nodal stage, CT was correct in 28/56 patients (50%), PET in 37/56 (66%), visual correlation in 40/56 (71%), and fusion in 41/56 (73%). It is concluded that in the exact localisation of metastatic thoracic LNs, the accuracy of reading of PET is increased if the PET images can be visually correlated with CT images. PET+CT anatometabolic fusion images add only a marginal benefit compared with visual correlation.

[Acute respiratory insufficiency revealing myasthenia gravis: apropos of 3 cases]. / Insuffisance respiratoire aiguë révélatrice d'une myasthénie juvénile: à propos de trois cas.

BACKGROUND: Myasthenia gravis is usually revealed by a ptosis or a diplopia. A respiratory muscle weakness often occurs during the course but an acute respiratory failure as initial feature is unusual. CASE REPORTS: Three girls, aged 8, 10 and 14 years, were hospitalised in an intensive care unit, along a 15 year-period, for an acute respiratory distress. The first two children suffered from skeletal and bulbar muscle weakness. The third, admitted with the diagnosis of unexplained pneumonia, was complaining of skeletal and bulbar muscle weakness for the last 18 months. Myasthenia gravis was confirmed with electromyography, and detection of the acetylcholine-receptors antibodies in all three cases. CONCLUSION: Any unexplained acute respiratory distress must lead to search for skeletal and bulbar muscle weakness, specially after muscular exercise or at the end of day, manifestations which characterize myasthenia gravis.

Prognostic significance of nm23 protein expression in malignant melanoma. An immunohistochemical study.

The NM23 genes, encoding for the red blood cell nucleoside diphosphate kinases A and B, have been found to serve as metastasis-suppressor genes in experimental animal models of tumour progression, and in some, but not all cancers in man. To investigate the role of NM23 in the progression of human malignant melanoma, we studied the expression and distribution of the nm23 protein with a sensitive immunohistochemical technique and a well-characterized monoclonal antibody in 41 benign pigment cell lesions and 71 uniformly treated malignant melanomas with a long follow up-up. In benign naevi, the junctional nests frequently expressed nm23 protein, whereas the immunoreactivity tended to decrease when the lesions matured. All malignant melanomas expressed nm23 protein in their vertical and/or radial growth phases, and the immunoreactivity tended to increase towards the deeper parts of the lesion. No relation was found between nm23 expression and patient outcome. In addition, nm23 was found in activated lymphoid cells, and this feature was significantly associated with a brisk lymphocytic stroma response in malignant melanomas. Our data are at variance with previous mRNA studies on malignant melanoma, and indicate that routine immunohistochemical analysis for nm23 protein on paraffin-embedded tumour tissue cannot reliably be used as a prognostic marker for patients suffering from malignant melanoma. In contrast, our findings suggest that the nm23 protein in pigment cell lesions is related to the proliferative or activated state of pigment cells, rather than to their metastatic potential.

Assessment of myocardial viability in chronic coronary artery disease using technetium-99m sestamibi SPECT. Correlation with histologic and positron emission tomographic studies and functional follow-up.

OBJECTIVES: The value of 99mTc-sestamibi (2-methoxy-isobutyl isonitrile [MIBI]) as a viability tracer was investigated in patients undergoing coronary artery bypass graft surgery. BACKGROUND: Initial studies claim that rest MIBI single-photon emission computed tomographic (SPECT) studies can be used to assess myocardial viability. METHODS: Thirty patients with a severely stenosed left anterior descending coronary artery and wall motion abnormalities were prospectively included. The patients underwent a MIBI rest study, a positron emission tomographic (PET) flow (13NH3) and metabolism (18F-deoxyglucose) study and nuclear angiography before undergoing bypass surgery. A preoperative transmural biopsy specimen was taken from the left ventricular anterior wall. Morphometry was performed to assess percent fibrosis. After 3 months, radionuclide angiography was repeated. RESULTS: Statistically significant higher MIBI values were found in the group with myocardial viability as assessed by PET than in the group with PET-assessed nonviability (p < 0.01). Significantly higher MIBI values were found in the group with enhanced contractility at 3 months (76 +/- 13% vs. 53 +/- 22%, p < 0.01). A linear relation was found between MIBI uptake and percent fibrosis in the biopsy specimen (r = 0.78, p < 0.00001). When maximizing the threshold for assessment of viability with MIBI by using functional improvement as the reference standard, a cutoff value of 50% was found, with positive and negative predictive values of 82% and 78%, respectively. CONCLUSIONS: 99mTc MIBI uptake was significantly higher in PET-assessed viable areas and in regions with enhanced contractility at 3 months. A linear relation was found between percent fibrosis and MIBI uptake. An optimal threshold of 50% was found for prediction of functional recovery.

[Hibernating myocardium and the 'no reflow' phenomenon: a study of absolute regional myocardial perfusion and glucose metabolism using positron emission tomography in chronic and acute heart disorders]. / Hibernerend myocard en het 'no reflow' fenomeen: een studie van absolute regionale myocardiale doorbloeding en glucosemetabolisme met positron emissie tomografie in chronisch en acuut hartlijden.

Positron emission tomography (PET) is a powerful tool for in vivo measurements of physiologic processes such as regional myocardial blood flow and metabolism. Myocardial blood flow is often studied using radioactive labeled ammonia (13NH3) while myocardial metabolism can be investigated using 18F-fluorodeoxyglucose (FDG). Moreover, the use of appropriate kinetic models allows quantification of these processes. In this study, myocardial viability in both chronic and acute heart disease was investigated by the use of positron emission tomography. In this context, viable refers to dysfunctioning areas of the myocardium in which functional recovery is observed after revascularization. In patients suffering chronic coronary artery disease, PET findings of flow and metabolism were correlated with myocardial ultrastructure. In dysfunctional myocardial segments, normal 13NH3 uptake or decreased 13NH3 uptake with relatively increased FDG uptake (PET mismatch) indicates the possibility for functional recovery after bypass surgery. Since absence of scar tissue in these segments is likely to be required for functional recovery, it was not surprising that little fibrosis was found in myocardial biopsies taken in PET mismatch areas. The biopsies also revealed the presence of viable myocardial cells showing a variable loss of contractile material. The contractile material was replaced by glycogen. One could wonder about the time course needed for functional recovery after restoration of blood flow in the presence of a considerable amount of cells lacking a normal contractile apparatus. It would therefore be interesting to study functional recovery at different time points in patients with variable amounts of these myolytic cells. Probably, recovery of contractility would be slower in myocardial areas with a larger amount of abnormal cells. Another question that arises is the meaning of the increased FDG signal in dysfunctional, though viable myocardium. At first sight, glycogen storage in myolytic cells seems an excellent candidate to explain the increased intake of FDG in PET mismatch areas. However, in this study, in areas considered nonviable by PET, similar amounts of myolytic cells were found. Histologically altered cells might represent a structural and protective adaptation to long term hypoperfusion or to repetitive episodes of ischemia. Another possibility for the increased FDG uptake is an enhancement of glucose utilization in the mismatch areas not only in the myolytic cells, but also in the morphologically normal cell fractions. In patients with a PET mismatch pattern, significant recovery of flow and function was observed after surgery with a significant decrease in glucose utilization. Although it would have been interesting to histologically study the fate of myolytic cells in these recovered areas, this was not possible for obvious ethical reasons. In areas considered non viable by PET expressing a concordant decrease of 13NH3 and FDG uptake (PET match), no recovery of function, flow or metabolism was noted at follow-up. Another study was conducted in our department in infarct patients in which regional myocardial blood was measured within 24 hours after successful thrombolysis. The aim was to investigate the presence of impaired tissue perfusion in the acute stage and to evaluate its effect on recovery of flow, metabolism and function. In about 30% of patients with a TIMI 3 patent vessel, seriously impaired tissue flow was observed in the acute stage. Whether this impairment was due to irreversible damage to capillaries or myocytes, to reperfusion injury or to the presence of multiple distal thrombi remains unknown. Most patients showing severely impaired regional myocardial blood flow in the acute stage revealed absence of viable myocardium on follow-up PET NH3/FDG scans.

[Perforating milia-like idiopathic calcinosis of the extremities in Down syndrome]. / Calcinose miliaire idiopathique perforante des extrêmités chez une malade trisomique 21.

INTRODUCTION: Several skin diseases can be seen in patients with trisomy 21. We report a case of miliary calcinosis of the extremities. CASE REPORT: A 15-year old adolescent with Down's syndrome presented small papular miliary lesions which had developed over 18 months and tended to discharge a chalk-like substance via the epidermis. Approximately 15 lesions were present on the hands and feet. Histologically, there was a well-delimited calcium deposit in the superficial dermis. There was no alteration in phosphorus/calcium metabolism. Brain CT-scan and cardiac echography did not reveal any calcifications. DISCUSSION: Miliary calcinosis cutis may not be exceptional in Down's syndrome, although only 9 observations have been reported. Preferential localizations include the hands, wrists and feet. Association with syringoma has been noted but would appear to be fortuitous. Transepidermal elimination of the calcium deposits is frequent. Pathogenic hypotheses include precipitation of calcium salts in sudation products and/or increased synthesis by fibroblasts. The association with trisomy 21 appears to be significant since only three cases have been reported in patients with normal karyotypes. This entity should be individualized as perforating milia-like idiopathic calcinosis cutis of the extremities.

PET scan predicts recovery of left ventricular function after coronary artery bypass operation.

BACKGROUND: Viable but hypocontractile myocardium can show functional improvement after revascularization (hibernation). It is sometimes difficult, however, to predict viability and recovery in patients with severe left ventricular function. This study sought to identify possible predictive factors of recovery of cardiac function after revascularization in patients with three-vessel disease. METHODS: Positron emission tomography (fluoro-18-deoxyglucose uptake for metabolism; nitrogen 13-labeled ammonia for flow) and equilibrium-gated nuclear angiography (for the global ejection fraction) were performed in 59 patients with three-vessel disease before and after undergoing coronary artery bypass grafting. The positron emission tomographic data were expressed as match normal (flow and metabolism normal), mismatch (low flow, high metabolism), match viable (moderate decrease in flow and metabolism), and match necrosis (low flow and metabolism). RESULTS: Stepwise logistic regression analysis showed that only mismatch regions played a significant role in predicting postoperative improvement in function (p = 0.019). There were 1.7 +/- 1.5 mismatch regions in 31 patients who showed an improvement in their ejection fraction (0.47 +/- 0.14 versus 0.58 +/- 0.11; mean +/- standard deviation) versus 0.8 +/- 1.0 mismatch regions (p = 0.017) in patients who did not show recovery. There was more pronounced functional improvement with increasing numbers of mismatch regions, and patients with at least one mismatch region had a high likelihood of recovery (p < 0.001). In patients with a very low preoperative ejection fraction and two or more mismatch regions, there was early significant recovery (0.27 +/- 0.08 versus 0.46 +/- 0.06; p = 0.009). CONCLUSIONS: At least one mismatch region must be present for there to be a postoperative functional benefit. When a low left ventricular ejection fraction is associated with mismatch, early recovery is substantial.

CD40 is a prognostic marker in primary cutaneous malignant melanoma.

CD40 is a receptor at the surface of B lymphocytes with important functions in the immune response. CD40 has also been found on a variety of carcinoma and melanoma cell lines where it has been suggested to serve as a possible receptor for mitogenic signals. We studied the expression and distribution of CD40 in paraffin sections of 71 uniformly treated malignant melanomas (MMs) with a long clinical follow-up using well known monoclonal antibodies. For comparison, 71 benign nevi were also studied. Common acquired nevi occasionally expressed CD40 in nests or single cells at the dermo-epidermal junction; no immunoreactivity was observed in the dermal part of acquired nevi, and all Spitz' nevi were entirely negative. One-third of large congenital nevi expressed CD40 in small clusters of heavily pigmented, epithelioid cells, corresponding to so-called proliferative nodules. In 41 of 71 MMs, CD40 was expressed in single or clustered neoplastic melanocytes; 9 cases showed CD40 expression only in the radial growth phase, and in 32 cases, the vertical growth phase showed CD40 expression. The same staining pattern was obtained with other anti-CD40 monoclonal antibodies, directed to different epitopes of the CD40 molecule. In 29 of 32 MMs showing CD40 in the vertical growth phase, expression of the CD40 ligand (CD40L) was studied; in 13 of these 29, CD40L was found in the same tumor areas that expressed CD40. Analysis of 28 metastases from 24 MM patients showed in the majority of cases a similar, scattered or nodular staining pattern as observed in the primary tumor. Patients expressing CD40 in the vertical growth phase of their MM did not differ significantly from CD40-negative patients with respect to any of the known prognostic parameters but showed a significantly shorter tumor-free survival. Patients with CD40+ CD40L+ MM tended to have a shorter tumor-free survival than those lacking CD40L. We conclude that CD40 represents a novel prognostic parameter in primary cutaneous MM. The co-localization of CD40 and CD40L suggests an autocrine growth loop in the vertical growth phase of MM.

[Celiac disease, cerebral calcifications and epilepsy syndrome]. / Le syndrome maladie coeliaque, calcifications cérébrales et épilepsie.

The syndrome of coeliac disease, epilepsy and cerebral calcifications is a rare complication of coeliac disease. The pathological changes consist in a patchy pial angiomatosis and resemble those of Sturge-Weber syndrome, whose variant without port-wine angioma must be ruled out. Typical course includes three stages leading to a severe encephalopathy. However, the mental impairment is extremely variable. The pathogenetic process is so for unknown; main clues involve a chronic folic acid deficiency or a HLA-related autoimmune disorder. Treatment requires early gluten-free diet and anti-epileptic drug.

Only hibernating myocardium invariably shows early recovery after coronary revascularization.

BACKGROUND: The aims of this study were to identify hibernating myocardium (hypocontractile, hypoperfused viable myocardium that regains contractility after revascularization) in the clinical setting and to predict functional outcome in patients with coronary artery disease after coronary revascularization. METHODS AND RESULTS: Preoperative data related to the anterior free wall of the left ventricle were collected in 50 coronary bypass surgery candidates (positron emission tomography [PET], [13N]NH3 for flow, and [18F]FDG for metabolism [MET]; equilibrium-gated nuclear angiography [EGNA] for regional ejection fraction [REF]; and histological data from myocardial biopsies for percentage fibrosis and viable myocytes). Three months after surgery, the patients had follow-up PET and EGNA investigations. A principal-components analysis identified four patient clusters. Cluster 1 (n = 9) had normal viable myocardium. Cluster 2 (n = 18) had viable hypocontractile myocardium (REF, 39 +/- 12%) showing a PET mismatch pattern. Cluster 3 (n = 16) had viable hypocontractile myocardium associated with morphological myocyte injury showing a matched moderate decrease in flow (66 +/- 11%) and MET (70 +/- 11%). Cluster 4 (n = 7) had hypocontractile myocardium with mainly scar tissue (fibrosis, 74 +/- 12%). After surgery, only cluster 2, with hibernating myocardium, showed significant improvement in REF (from 39 +/- 12% to 50 +/- 13%, P < .05). Cluster 3, with sites of morphological myocyte injury, showed no recovery. The stepwise logistic regression showed a combination of low preoperative REF and high MET to be the best predictor of functional recovery (P < .008). CONCLUSIONS: Multivariate analysis identifies hibernating myocardium showing early postrevascularization recovery, as opposed to viable but myolytic myocardium with no early recovery. Postrevascularization recovery can be predicted (combination of low REF and high MET) by noninvasive techniques.

Prognostic significance of bone marrow trephine and peripheral blood smears in 55 patients with mantle cell lymphoma.

Bone marrow trephine and peripheral blood smears taken at diagnosis of 55 cases of well-documented mantle cell lymphomas were reviewed in order to analyse the leukaemic involvement in this non-Hodgkin's lymphoma: its incidence, morphological characteristics and prognostic significance. A median survival of 36 months was found. The median age was 61 and the male to female ratio was 4:1. Morphologically 7 cases presented with a mantle zone pattern, all the others had a diffuse pattern. Involvement of the bone marrow was found in 58% and a trend for prolonged survival in patients with a negative trephine was seen. An absolute lymphocytosis above 10,000 mu l was found at diagnosis in 5 cases (10%) and had a statistically significant impact on survival. An additional 5 cases developed frank leukaemia during the course of the disease and died within 1 to 6 months of this evolution, suggesting that marked lymphocytosis is more a terminal event associated with an extremely poor prognosis than a presenting symptom. Finally we identified an additional parameter with statistically prognostic significance, namely, the presence of atypical cells in the peripheral blood even in the absence of an increased lymphocytosis.

Regional myocardial blood flow, glucose utilization and contractile function before and after revascularization and ultrastructural findings in patients with chronic coronary artery disease.

In patients with chronic coronary artery disease, follow-up measurements of myocardial blood flow, metabolism and function were correlated with histology. In 41 patients with chronic coronary artery disease and a severely stenosed left anterior descending coronary artery, a positron emission tomographic (PET) flow/metabolism study and nuclear angiography were performed immediately before and 3 months after bypass surgery. Biopsies were taken from the left ventricular anterior wall at the time of surgery. Control biopsies were taken from donor hearts for cardiac transplantation and from hearts of patients with a defect of the atrial septum. A significant improvement of flow (P<0.01) and regional contractile function (P<0.01) was observed in the mismatch group. Glucose utilization was significantly lower (P<0.001) as compared to preoperative values. The group with preserved flow and the PET match group revealed no significant changes in flow, metabolism or function. Control biopsies revealed significantly less myolytic cells as compared to biopsies taken from both match and mismatch groups (P<0.01) and less fibrosis as compared to biopsies taken from the match group (P<0.01). Postoperatively, linear relationships were found between flow and both % fibrosis (r = 0.71, P<0.001) and regional anterior ejection fraction (r = 0.7, P<0.001). Only mismatch areas revealed significant recovery of both flow and function after revascularization with a disappearance of enhanced glucose uptake. The better linear correlation between flow and % fibrosis after surgery as compared to preoperatively was probably due to improvement of flow values in the mismatch group.

Metabolism of nitrogen-13 labelled ammonia in different conditions in dogs, human volunteers and transplant patients.

To investigate the rate of metabolism of nitrogen-13 labelled ammonia (13NH3) in different conditions, we have determined the relative amount of unchanged 13NH3 in the blood of dogs, volunteers and transplant patients at different times following injection. In dogs, the determinations were made under basal conditions, during adenosine administration and after coronary occlusion. The results show that adenosine administration increases the metabolic rate whereas coronary occlusion does not affect 13NH3 metabolism. For both human volunteers and transplant patients the metabolic rate of 13NH3 was assessed under basal conditions and during adenosine administration. 13NH3 metabolism proceeds faster in transplant patients than in volunteers under both conditions. Adenosine administration causes a faster 13NH3 turnover in volunteers but not in transplant patients. Application of individual metabolite correction resulted in a 16% decrease in the calculated blood flow compared to uncorrected values. A smaller difference (5%) was observed between correction with mean metabolite values and individually acquired metabolite values.

Histological alterations in chronically hypoperfused myocardium. Correlation with PET findings.

BACKGROUND: In patients with chronic coronary artery disease (CAD) and left ventricular dysfunction, flow/metabolic studies of the myocardium with positron emission tomography (PET) are able to distinguish viable but dysfunctional myocardium from irreversible ischemic injury and scar tissue. In this study, PET findings of blood flow and metabolism in chronically hypoperfused myocardium were correlated with histology. METHODS AND RESULTS: We studied 33 patients suffering from CAD. In each patient, myocardial blood flow and metabolism were measured with PET 1 or 2 days before revascularization. During surgery, transmural biopsies were taken from the left ventricular anterior wall and planimetrically scored for the degree of myolysis (sarcomere loss). The amount of connective tissue was calculated using morphometric techniques. Contrast ventriculography demonstrated abnormal wall motion in 23 patients. Fourteen patients with a mismatch pattern (decreased flow with preserved metabolism) in the biopsy region after quantitative analysis of the PET data showed 11 +/- 6 vol% fibrosis and 25 +/- 13% cells with sarcomere loss. The space formerly occupied by sarcomeres was mainly replaced by glycogen and mitochondria. A significant wall motion improvement was noted 3 months after surgery. Nine patients showed a match pattern (concordant flow/metabolism defects). The biopsies revealed 35 +/- 25% fibrosis and 24 +/- 15% glycogen-storing cells. The biopsies of the 10 patients with normal anterior wall motion showed 8 +/- 4% fibrosis and 12 +/- 8% glycogen-accumulating cells. CONCLUSIONS: It can be concluded that areas with impaired wall motion and a PET match pattern show extensive fibrosis. Regions with reduced flow and preserved FDG metabolism, however, contain predominantly viable cells. In these regions, significant recovery of wall motion is found after revascularization. Regions with normal wall motion contain predominantly viable cells. Cells with reduced contractile material and increased glycogen content are mainly found in areas with wall motion impairment but are also present in areas with normal wall motion and a severe stenosis of the coronary vessel.

[Brain abscess complicating dental caries in children]. / Abcès cérébraux de l'enfant compliquant des caries dentaires.

Brain abscess following dental or periapical infection is rare in childhood. This report describes brain abscesses found in two children with dental caries. Case 1.--A 12 year-old boy was admitted because he had suffered from acute meningitis for 3 days. Clinical examination showed symptoms of meningitis plus palsy of the right third and fourth cranial nerves and of the left facial nerve, and a defect in the left temporal field. Funduscopic examination showed papilledema; CT scan and MRI showed a ring-shaped lesion in the right occipital area. The patient was given cefotaxime and thiamphenicol. The abscess was drained; bacteriological examination showed Actinomyces viscosus and Peptostreptococcus magnus. The neurological condition and the CT scan lesion improved, but intracranial pressure increased again on the 17th day after the onset, requiring replacement of the antibiotics by rifampicin and ampicillin plus clavulanic acid for 2 months. This brain abscess appeared to be metastatic, derived from the infection of a large dental cyst due to a dental infection that had been treated 6 months earlier. Case 2.--A 8 1/2 year-old girl was admitted because she was suffering from palsy of the left facial nerve and left arm. She had had headaches and fever for a few days. Clinical examination showed the palsies and drowsiness. CT scan showed two brain abscesses. The patient was given ceftriaxone, fosfocin and metronidazole. She had been treated for a gingival abscess 1 month earlier, and had two infected teeth extracted. Improvement of the intracranial pressure was transient and the antibiotics were changed on the 12th day of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)