Iodine excretion during stimulation with rhTSH in differentiated thyroid carcinoma

AIM

Elevated iodine intake is a serious problem in the diagnostic and therapeutic application of (131)iodine in patients with differentiated thyroid cancer. Therefore, iodine avoidance is necessary 3 months in advance. Additionally, endogenous stimulation requires withdrawal of thyroid hormone substitution for 4 weeks. Exogenous stimulation using recombinant human TSH (rhTSH) enables the continuous substitution of levothyroxine, which contains 65.4% of its molecular weight in iodine. Thus, a substantial source of iodine intake is maintained during exogenous stimulation. Although this amount of stable iodine is comparable to the iodine intake in regions of normal iodine supply, it may reduce the accumulation of radioiodine in thyroid carcinoma tissue. The aim of this study was to assess the iodine excretion depending on different ways of stimulation.

METHODS

Iodine excretion was measured in 146 patients in the long term follow up after differentiated thyroid carcinoma. Patients were separated into 2 groups, those on hormone withdrawal (G I) and rhTSH-stimulated patients on hormone substitution (G II).

RESULTS

Iodine excretion was significantly lower in hypothyroid patients (G I, median 50 micro g/l, range: 25-600 micro g/l) than in those under levothyroxine medication (G II, median 75 micro g/l, 25-600 micro g/l, p <0.027). TSH in G I (median 57.0 micro U/ml, range: 14.4-183 micro U/ml) was significantly lower (p <0.001) than in G II (117 micro U/ml, 32.2-281 micro U/ml).

CONCLUSION

Iodine excretion was higher in patients under rhTSH-stimulation than after hormone withdrawal. This may indicate an increased iodine pool in rhTSH-stimulated patients (deiodination of levothyroxine), thus limiting the sensitivity of radioiodine scanning to the level of endogenous stimulation despite significantly higher TSH levels during rhTSH-stimulation.

Multicenter study differentiated thyroid carcinoma (MSDS). Diminished acceptance of adjuvant external beam radiotherapy

AIM

The Multicenter Study Differentiated Thyroid Carcinoma (MSDS) is an ongoing study in Germany, Austria, and Switzerland on the clinical benefit of adjuvant external beam radiotherapy (RTx) for locally invasive differentiated thyroid carcinoma (DTC) in TNM stages pT4 pN0/1/x M0/x (5th ed. 1997).

METHODS

MSDS was designed as a prospective randomized trial. Patients receive thyroidectomy, radioiodine therapy (RIT) to ablate the thyroid remnant, and TSH-suppressive L-thyroxine therapy with or without RTx after documented elimination of cervical iodine-131 uptake (http://msds-studie.uni-muenster.de).

RESULTS

311 patients were enrolled between January 2000 and March 2003. 279 patients met the trial's inclusion criteria. 45 consented to randomization, of whom 17 were randomized into treatment arm A (RTx) and 18 into arm B (no RTx). Advised by the trial's independent Data Monitoring and Safety Committee, the MSDS steering committee decided to terminate randomization in April 2003 and continue MSDS as a prospective cohort study. 23 of the 234 patients in the observation arm of the trial were prescribed RTx by their physicians. Thus, 14% of the trial cohort were randomized or assigned to receive RTx (in-tention-to-treat analysis). In contrast, at least 44% of all patients with pT4 papillary DTC in Germany in the nation-wide PCES study underwent RTx in 1996 (p <0.001, chi(2)-test).

CONCLUSIONS

Acceptance of external beam RTx as a treatment modality for DTC has receded to a degree that accrual of a sufficient number of patients for a randomized trial has been impossible. Observation of the trial cohort is continued in order to assess clinical event rates with and without RTx and chronic RTx toxicity.

Design of new beta1-selective adrenoceptor ligands as potential radioligands for in vivo imaging

In general, the failing human heart is characterized by a selective reduction in beta(1)-adrenoceptors (beta(1)-ARs) without change in beta(2)-AR density. Medical imaging techniques, either single photon emission computed tomography (SPECT) or positron emission tomography (PET) with appropriate radioligands, offer the possibility of assessing beta-adrenoceptor density non-invasively in humans. To date, neither a SPECT nor a PET radioligand is available for the selective imaging of cardiac beta(1)-ARs. The aim of this study was to develop potential high affinity beta(1)-selective AR radioligands for the non-invasive in vivo imaging of the beta(1)-AR density in the human heart using SPECT or PET. A variety of racemic N-aryl-N'-[2-[3-aryloxy-2-hydroxy-propylamino]-ethyl]-urea derivatives and chain-elongated analogues, related to the established beta(1)-AR antagonist, ICI 89,406 8i, were synthesized. Competition studies using the non-selective AR ligand, [(125)I]iodocyanopindolol ([(125)I]ICYP), and ventricular membrane preparations of wild-type mice revealed nine ligands with higher beta(1)-AR affinities (up to 76-fold) and beta(1)-AR selectivities (up to 139-fold) than 8i. Mostly, these ligands possess a 2-substituted phenoxy group and a 4-substituted phenyl residue in contrast to the lead compound 8i. The non-radioactive counterparts of the desired SPECT- and PET-radiotracers were synthesized as reference compounds [e.g., 8f, 8g, 8h and 8l as the non-radioactive analogues of the radioiodinated SPECT radioligands, 8e and 8h as the non-radioactive compounds of C-11 labelled PET-tracers (C-11 in the methoxy group)]. The established library of high affinity beta(1)-selective AR antagonists was screened for chemical precursors for the radiosynthesis of the mentioned radioligands. Furthermore, the library consists of some comparison compounds that are unsubstituted, allyl- and alkyl-substituted or chain-elongated (e.g., 8a, 8j, 8o and 8r-t). Future steps will include radiolabelling and pharmacokinetic evaluation of the beta(1)-selective target compounds, which could be applied as sympathetic innervation agents for in vivo investigations and diagnostics in patients suffering from cardiac diseases like heart failure and ventricular arrhythmias.

[High non-specific binding of the beta(1) -selective radioligand 2-(125)I-ICI-H]

AIM

As results of cardiac biopsies suggest, myocardial beta(1) -adrenoceptor density is reduced in patients with chronic heart failure. However, changes in cardiac beta(2)-adrenoceptors vary. With suitable radiopharmaceuticals single photon emission computed tomography (SPECT) and positron emission tomography (PET) offer the opportunity to assess beta-adrenoceptors non-invasively. Among the novel racemic analogues of the established beta(1)-selective adrenoceptor antagonist ICI 89.406 the iodinated 2-I-ICI-H showed high affinity and selectivity to beta(1)-adrenoceptors in murine ventricular membranes. The aim of this study was its evaluation as a putative sub-type selective beta(1)-adrenergic radioligand in cardiac imaging.

METHODS

Competition studies in vitro and in vivo were used to investigate the kinetics of 2-I-ICI-H binding to cardiac beta-adrenoceptors in mice and rats. In addition, the radiosynthesis of 2-(125)I-ICI-H from the silylated precursor 2-SiMe(3)-ICI-H was established. The specific activity was 80 GBq/ micro mol, the radiochemical yield ranged from 70 to 80%.

RESULTS

The unlabelled compound 2-I-ICI-H showed high beta(1)-selectivity and -affinity in the in vitro competition studies. In vivo biodistribution studies apparently showed low affinity to cardiac beta-adrenoceptors. The radiolabelled counterpart 2-(125)I-ICI-H showed a high degree of non-specific binding in vitro and no specific binding to cardiac beta(1)-adrenoceptors in vivo.

CONCLUSION

Because of its high non-specific binding 2-(125)I-ICI-H is no suitable radiotracer for imaging in vivo.

Malignant melanoma and (18)F-FDG-PET: Should the whole body scan include the legs?

AIM

(18)F-FDG-PET (FDG-PET) is established in staging and follow-up of malignant melanoma. The legs are affected in 10-40% at time of diagnosis even if the primary is at the arms and torso. Imaging including the legs may detect distant manifestations but increases duration of the scan by approximately 30 min. We intended to disclose the diagnostic benefit of scanning the legs and to evaluate the therapeutic benefit resulting.

PATIENTS, METHODS

In this retrospective analyse 213 consecutive PET studies of 153 patients with suspected or recent malignant melanoma were re-evaluated for metastatic spread by a blinded investigator. Histopathological follow-up was assessed for confirmation.

RESULTS

Suspicious findings at the legs were depicted in 53 patients on 76 occasions. 38/53 showed pathologic uptake in the torso as well. In 15/53 patients it was restricted to the legs. One of them had a hitherto unknown, clinically relevant finding that was not apparent in palpation and inspection. In 6 other patients with primary location at the legs a validation of the positive PET findings was not possible up to now.

CONCLUSION

Metastases and local recurrence of malignant melanoma at the legs were found in 41% of women and 27% of men. However, a long scan does not yield relevant additional data. We found isolated new manifestations at the legs in only 1/153 patients. We recommend performing a long scan only in patients with previous melanoma manifestations restricted to the legs. In all other cases a short scan of the torso and proximal thighs is sufficient. This allows a higher number of PET-scans without loss of diagnostic power and a shorter examination time.

[Sentinel lymph node dissection in patients with malignant melanoma. Diagnostic and therapeutic standards]

INTRODUCTION

In patients with cutaneous malignant melanoma, the sentinel lymph node (SLN) reflects the histopathological features of the lymphatic basin with high accuracy.

MATERIAL AND METHODS

Three hundred eighty-one melanoma patients at the Hornheide clinic with an overall follow-up of 36 months (November 1998 to October 2001) underwent sentinel lymph node dissection (SLND).

RESULTS

The SLNs were successfully found in 93% of truncal melanoma ( n=136), 97% of melanoma of the extremities ( n=184), and 86% of melanoma of the head and neck region ( n=61). Of truncal midline melanomas, 84% ( n=43) showed two or more regional basins, in contrast to 18% of nonmidline melanoma ( n=93). Histopathological analysis revealed occult nodal disease in 25% of all patients. Completion lymphadenectomy revealed residual nodal disease in 8% of all patients with low risk melanoma with a tumor thickness of 0-1.5 mm (two of 26 patients with positive SLN) and in 11% of all patients with high risk melanoma with tumor thickness above 1.5 mm (eight of 70 patients with positive SLN). Tumor relapse was noted in 5% of negative SLN patients and 14% of positive SLN patients. The results of the method were false negative in 2% with a sensitivity of 98%.

CONCLUSION

Sentinel lymph node dissection is a reliable and accurate method of staging regional lymph nodes for all primary tumor sites. It can localize occult metastases in unexpected lymphatic basins and provides critical indications for completion lymphadenectomy. It represents an essential method of establishing stratification criteria for future adjuvant trials. Further long-term follow-up is needed to investigate its prognostic relevance to recurrence and overall survival.

[Guideline for in vivo- and in vitro procedures for thyroid diseases (version 2)]

The version 2 of the guideline for diagnostic standards of thyroid disorders is an update of the guideline published in 1999 and describes standards of in vitro and in vivo procedures. The following statements are modified: In vitro procedures: When measurement of the TSH-receptor antibodies is indicated, the guideline recommends the use of a second generation assay (recombinant human TSH-receptor as antigen). The functional assay sensitivity for the measurement of thyroglobulin should reach a value < or =1 ng/ml. Molecular genetic tests (RET proto-oncogene) are indicated in patients with a newly diagnosed medullary thyroid cancer and in the relatives of patients with hereditary medullary thyroid cancer. In vivo procedures: The sonographic examination should use a probe with a frequency of at least 7.5 MHz. Indications for the thyroid scintigraphy: nodule size > or =1 cm in diameter, autonomous goitre/nodule with clinical or subclinical hyperthyroidism, necessity of a differentiation between Graves' disease and chronic lymphocytic thyroiditis, therapy control after a definitive treatment and - in individual cases - the follow-up of untreated autonomous nodules.

Assessment of therapy response by FDG PET in pediatric patients

Little is known about the clinical value of FDG PET for assessing treatment response in pediatric oncology. After systematic review of literature, the very few publications concerning response control in pediatric oncology using FDG PET are summarized. There were only 4 studies concerning FDG PET in the assessment of therapy response in pediatric patients. None of the publications fulfilled the requirements for high quality studies because of the small number of patients studied. The clinical value of FDG PET in the assessment of therapy response in pediatric oncology is likely in osseous sarcomas and possibly in high-grade brain tumors. In other pediatric tumor entities such as lymphomas, soft-tissue sarcomas, germ cell tumors, or neuroblastomas, the clinical usefulness of FDG PET can either be assumed analogous to adults, or can be assumed from staging studies, or is still unknown. There is a need for large, systematic studies evaluating FDG PET in therapy monitoring, but also in grading, staging, and in the diagnosis of recurrences in pediatric malignancies.

Radioligands for imaging myocardial alpha- and beta-adrenoceptors

Alpha- and beta-adrenoceptors play an important role in the control of heart function. According to their molecular, biological, and pharmacological characteristics, they are subdivided into alpha(1)-, alpha(2)- and beta(1)-, beta(2)-, beta(3)-, beta(4)-adrenoceptors. In cardiac disease, there is often a selective downregulation of beta(1)-adrenoceptors associated with a relative increase in beta(2)- and alpha(1)-adrenoceptors. Functional imaging techniques like single-photon emission tomography (SPECT) and positron emission tomography (PET) provide the unique capability for non-invasive assessment of cardiac adrenoceptors. Radioligands with high specific binding to cardiac alpha- and beta-adrenoceptors suitable for radiolabelling are required for clinical studies. The non-selective beta-adrenoceptor antagonist [(11)C]CGP-12177 was used to quantify beta-adrenoceptor density using PET in patients with heart disease. New non-selective ligands (e. g. [(11)C]CGP-12388, [(18)F]CGP-12388, [(11)C]carazolol and [(18)F]fluorocarazolol) are currently evaluated; beta(1)-selective radioligands (e. g. [(11)C]CGP-26505, [(11)C]bisoprolol, [(11)C]HX-CH 44) and beta(2)-selective radioligands (e. g. [(11)C]formoterol, [(11)C]ICI-118551) were assessed in animals. None of them turned out as suitable for cardiac PET. Potential radioligands for imaging cardiac alpha(1)-adrenoceptors are based on prazosin. Whereas [(11)C]prazosin shows low specific binding to myocardium, its derivative [(11)C]GB67 looks more promising. The putative alpha(2)-adrenoceptor radioligand [(11)C]MK-912 shows high uptake in rodent myocardium but has not yet been evaluated in man. A number of radioligands were evaluated for assessing cardiac adrenoceptors using PET. New radioligands are needed to provide more insight into cardiac pathophysiology which may influence the therapeutic management of patients with cardiovascular disease.

Biochemical mechanisms of hibernation and stunning in the human heart

BACKGROUND

Myocardial hibernation and stunning are characterized by depressed cardiac function in the presence of reduced or normal coronary blood flow. The underlying biochemical mechanisms are widely unknown and only limited data are available in human hearts.

METHODS AND RESULTS

Left ventricular transmural myocardial biopsies were obtained from normal and dysfunctional segments of patients undergoing coronary bypass surgery. Segments were classified as hibernating (n=10) or stunned (n=9) using contrast ventriculography and echocardiography, single photon emission computed tomography (SPECT), and positron emission tomography (PET). In each patient, biopsies from normal myocardial segments were used as controls (n=19). Compared to control myocardium, levels of cAMP (3'-5'cyclic adenosine monophosphate, in fmol/mg wet weight, means+/-S.E.M.) were higher in hibernating (673+/-76 versus 518+/-47, P<0.05) but unchanged in stunned myocardium (513+/-73 versus 466+/-97, P>0.05). Protein expression of phospholamban, sarcoendoplasmic Ca(2+)-ATPase 2a, calsequestrin, the inhibitory subunit of troponin, as well as the activation of p38 MAP kinase were not different when compared to controls. However, heat shock protein 72 (Hsp72) was increased 55% in stunned (2.89+/-0.58 versus 1.86+/-0.32, P<0.05) but not in hibernating myocardium (1.68+/-0.34 versus 1.67+/-0.29, P>0.05).

CONCLUSIONS

The data from the present study suggest different pathophysiological mechanisms for myocardial hibernation and stunning. Alterations in the homeostasis of cAMP might be a compensatory mechanism in myocardial hibernation, whereas expression of Hsp72 appears to be cardioprotective in human myocardial stunning. Future studies should further elucidate these mechanisms and their potential impact on future therapeutic interventions.

Noninvasive grading of untreated gliomas: a comparative study of MR imaging and 3-(iodine 123)-L-alpha-methyltyrosine SPECT

PURPOSE

To compare the accuracy of magnetic resonance (MR) imaging scores with that of 3-(iodine 123)-L-alpha-methyltyrosine ((123)I-IMT) single photon emission computed tomography (SPECT) in the noninvasive grading of untreated gliomas.

MATERIALS AND METHODS

The study comprised 15 patients with low-grade gliomas (grades I-II, according to World Health Organization criteria) and 33 patients with high-grade gliomas (grades III-IV). The lesions were evaluated by using an MR imaging score based on nine criteria. The (123)I-IMT uptake was quantified as the ratio between the amino acid uptake in the tumor and that in the contralateral hemisphere. To test for potentially significant differences in diagnostic performance between contrast material-enhanced MR imaging and (123)I-IMT SPECT, binormal receiver operating characteristic curves were fitted to the data and compared by using the area test.

RESULTS

The accuracy of MR imaging in the noninvasive grading of untreated gliomas was higher than that of (123)I-IMT SPECT (88% vs 79%). However, the difference in diagnostic performance was not significant on the basis of findings at receiver operating characteristic analysis (P >.2). Neither MR imaging nor (123)I-IMT SPECT allowed differentiation between high-grade gliomas (grades III and IV).

CONCLUSION

Although (123)I-IMT uptake is significantly higher in high-grade gliomas than in low-grade gliomas, the performance of (123)I-IMT SPECT adds little to the accuracy of determining tumor grade when MR imaging is performed.

I-123-lodo-alpha-methyl tyrosine SPECT in non-parenchymal brain tumours

PURPOSE

Scintigraphy using I-123-iodo-alpha-methyl tyrosine (IMT) is useful in the preoperative characterization of gliomas, in detecting recurrent glioma and in the biological re-evaluation of residual or recurrent tumours. A systematic evaluation of non-parenchymal brain tumours has not yet been performed. The aim of the present study was to evaluate IMT SPECT in the management of intracerebral metastases and lymphomas.

PATIENTS AND METHODS

IMT uptake was analyzed in 31 patients with 28 metastases of extracerebral solid tumours and 7 cerebral lymphomas. Histology revealed high grade lymphomas, melanomas, and carcinomas of the following origin: lung, unknown primary, breast, colon, renal cell, ovary, vagina, frontal sinus. IMT uptake was quantified as ratio between maximal tumour accumulation and average uptake in the contralateral hemisphere.

RESULTS

All tumours except two renal cell and one small cell lung carcinoma metastases accumulated IMT (91%). The highest IMT uptake was found in a metastasis of lung carcinoma. IMT uptake was highly variable and was similar in primary and in recurrent tumours.

CONCLUSION

Significant accumulation of IMT is seen in the majority of tumours, so that this technique might be helpful for the management of cerebral metastases and lymphomas.

Prognostic significance of (18)F-FDG and (99m)Tc-methylene diphosphonate uptake in primary osteosarcoma

The purpose of this retrospective analysis was to evaluate the prognostic significance of both initial glucose metabolism as measured by (18)F-FDG PET and osteoblastic activity as measured by (99m)Tc-methylene diphosphonate (MDP) bone scintigraphy in osteosarcoma.

METHODS

In 29 patients (18 male, 11 female; age range, 5-41 y) with primary osteosarcoma, (18)F-FDG uptake and (99m)Tc-MDP uptake were measured semiquantitatively (average and maximum tumor-to-nontumor ratios [T/NT(av) and T/NT(max), respectively]) using PET and bone scintigraphy at the time of diagnosis. After chemotherapy, the patients underwent surgery for their primary tumor, and the response was determined histologically. Cumulative overall survival and event-free survival were determined by clinical and imaging follow-up of 7-72 mo (median, 28 mo).

RESULTS

Clinical and imaging follow-up revealed that the disease relapsed or failed to achieve complete remission in 9 patients and that 6 patients died of the disease. Both overall and event-free survival were significantly better in patients with a low (18)F-FDG T/NT(max) (less than the median) than in patients with a high (18)F-FDG T/NT(max) (at least the median). The negative relationship of (18)F-FDG T/NT(av), (99m)Tc-MDP T/NT(max), and (99m)Tc-MDP T/NT(av) with overall and event-free survival did not reach a level of significance. (18)F-FDG uptake values correlated moderately and positively with (99m)Tc-MDP uptake values, but a level of significance was reached only between (18)F-FDG T/NT(max) and (99m)Tc-MDP T/NT(av).

CONCLUSION

The initial glucose metabolism of primary osteosarcoma as measured by (18)F-FDG PET using T/NT(max) provides prognostic information. High (18)F-FDG uptake correlates with poor outcome. Thus, (18)F-FDG uptake may be complementary to other well-known factors in judging the prognosis in osteosarcoma.

Prognostic significance of amino acid transport imaging in patients with brain tumors

OBJECTIVE

To evaluate the prognostic significance of presence, intensity, and extent of amino acid uptake in patients with suspected primary or recurrent brain tumors.

METHODS

We retrospectively analyzed 181 consecutive studies of amino acid uptake using single-photon emission computed tomography and the amino acid l-[3-(123)I]iodo-alpha-methyltyrosine (IMT). In a blinded analysis, all studies were evaluated for presence, maximal uptake (IMT(max)), and extent (IMT(ext)) of focal tracer uptake.

RESULTS

The most frequent tumors were 53 astrocytomas (World Health Organization Grade I-III), 41 glioblastomas, 16 metastases, 13 oligodendrogliomas (Grade II-III), and 10 medulloblastomas. The other patients exhibited various parenchymal tumors or nonneoplastic lesions. IMT uptake was present in 69% of the patients with IMT(max) ranging from 1.4 to 6.2. IMT(max) and IMT(ext) were significant predictors of survival in the whole group. When the group was divided according to primary versus recurrent tumor, only the primary tumors achieved a high level of significance (P < 0.01). When patients without any IMT uptake were excluded from the analysis, statistical significance for both IMT(max) and IMT(ext) was lost. Multiple regression analysis, including IMT(max), IMT(ext), age, and tumor grade, revealed only extent of IMT uptake as an independent predictor of prognosis.

CONCLUSION

Absence of IMT uptake is a significant predictor of long-term survival in patients with suspected primary or recurrent brain tumors. Only the extent of a given lesion provided minor supplementary prognostic information as compared with histopathology and age. These findings suggest caution in relating high amino acid uptake values to poor prognosis, despite the capability of amino acid imaging to help determine the presence and extent of gliomas.

3-[123I]Iodo-L-alpha-methyl tyrosine transport into human fibroblasts and comparison with Ewing's sarcoma cells

The cellular transport systems and the transport kinetics of [123I]IMT uptake into non-malignant extracranial cells were characterized for the first time. Human fibroblasts were chosen as non-malignant extracranial cells as they are found ubiquitous in the body. [123I]IMT is exclusively transported into fibroblasts via the sodium independent system L. An apparent Michaelis constant K(m) = 116.2 +/- 18.9 microM and a maximum transport velocity V(max) = 191.6 +/- 13.9 pmol x (10(6) cells)(-1) x min(-1) were calculated for the sodium-independent transport. These results were compared with those determined in two malignantly transformed extracranial cell lines, the human Ewing's sarcoma cell lines VH-64 and CADO-ES-1.

Cardiac autonomic dysfunction in Brugada syndrome

BACKGROUND

Patients with Brugada syndrome present with characteristic ECG abnormalities (atypical right bundle-branch block and ST-segment elevation) and life-threatening ventricular tachyarrhythmias despite structurally normal hearts. Involvement of the autonomic nervous system is suggested by the occurrence of ventricular tachyarrhythmias and sudden death at rest or during sleep and by changes of typical ECG signs under pharmacological modulation of the myocardial autonomic tone.

METHODS AND RESULTS

This study investigated the presynaptic cardiac neuronal reuptake of norepinephrine (uptake 1) in 17 patients with Brugada syndrome and 10 age-matched control subjects with the use of the norepinephrine analogue [123I]m-iodobenzylguanidine (123I-MIBG), single-photon emission CT (SPECT), and quantitative 33-segment bull's-eye analysis. Regionally reduced 123I-MIBG uptake was present in 8 (47%) of 17 patients with Brugada syndrome but in none of the control subjects. Quantitative analysis showed segmental reduction of 123I-MIBG uptake in the inferior and septal left ventricular wall in patients with Brugada syndrome compared with control subjects (P<0.05). No correlation was found between the findings of 123I-MIBG-SPECT and clinical characteristics of the study patients.

CONCLUSIONS

The present study demonstrated an abnormal 123I-MIBG uptake in patients with Brugada syndrome, indicating presynaptic sympathetic dysfunction of the heart. These findings may have potential impact on the pathophysiology and arrhythmogenesis in patients with Brugada syndrome. Future quantitative investigations of the presynaptic and postsynaptic sympathetic and parasympathetic branches of the cardiac autonomic nervous system may clarify whether these observations represent a primary adrenergic dysfunction or an imbalance between sympathetic and parasympathetic innervation of the heart.

Moyamoya syndrome: impaired hemodynamics on ECD SPECT after EEG controlled hyperventilation

BACKGROUND AND PURPOSE

Ischemic symptoms in children with Moyamoya syndrome are typically provoked by hyperventilation (HV) and are accompanied by the "re-build-up" phenomenon in EEG. The value of scintigraphic detection of HV-provoked perfusion deficits remains to be elucidated.

PATIENTS AND METHODS

In seven children with Moyamoya syndrome regional cerebral blood flow was assessed by 99mTc-ethyl-cysteine-dimer (ECD) single photon emission computed tomography (SPECT) after HV and under baseline conditions to identify ischemia prone regions.

RESULTS

Regional marked hypoperfusion after HV was found in all patients. Predominant perfusion deficits were detected in the frontal lobes.

CONCLUSION

ECD SPECT is a potential tool for the preoperative evaluation of cerebral hemodynamics and for monitoring angiosurgical therapies in Moyamoya disease.

FDG-PET for detection of recurrences from malignant primary bone tumors: comparison with conventional imaging

BACKGROUND

The aim of this study was to assess the diagnostic ability of positron emission tomography using 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG-PET) in the detection of recurrences from malignant primary bone tumors compared with conventional imaging.

PATIENTS AND METHODS

In 27 patients (6 osteosarcomas, 21 Ewing's sarcomas), 41 FDG-PET examinations performed for diagnosis or exclusion of recurrent disease were evaluated. Conventional imaging techniques consisted of magnetic resonance imaging of the primary tumor site, thoracic computed tomography, and Tc-99m methylene diphosphonate bone scintigraphy. The reference methods were the histopathological analysis and/or the clinical and imaging follow-up.

RESULTS

In 25 examinations reference methods revealed 52 sites of recurrent disease (local n = 7; distant: osseous n = 22, pulmonary n = 13, soft tissue n = 10). On an examination-based analysis FDG-PET had a sensitivity of 0.96, a specificity of 0.81 and an accuracy of 0.90. Corresponding values for conventional imaging were 1.0, 0.56 and 0.82.

CONCLUSIONS

The sensitivity, specificity and accuracy of FDG-PET in the detection of recurrences from osseous sarcomas are high. On an examination-based analysis, FDG-PET had a not significantly lower sensitivity in comparison with conventional imaging. However, FDG-PET showed a small advantage in the detection of osseous and soft-tissue recurrences compared with conventional imaging.