E. Klemm

Fluorine-18 fluorodeoxyglucose positron emission tomography in the follow-up of differentiated thyroid cancer

Whole-body fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging was performed during the follow-up of 33 patients suffering from differentiated thyroid cancer. Among them there were 26 patients with papillary and seven with follicular tumours. Primary tumour stage (pT) was pT1 in six cases, pT2 in eight cases, pT3 in three cases and pT4 in 14 cases. FDG PET was normal in 18 patients. In three patients a slightly increased metabolism was observed in the thyroid bed, assumed to be related to remnant tissue. In one case local recurrence, in ten cases lymph node metastases (one false-positive, caused by sarcoidosis) and in three cases distant metastases were found with FDG PET. In comparison with whole-body scintigraphy using iodine-131 (WBS) there were a lot of discrepancies in imaging results. Whereas three patients had distant metastases (proven with131I) and a negative FDG PET, in four cases131I-negative lymph node metastases were detectable with PET. Even in the patients with concordant ‘staging”, differences between131I and FDG were observed as to the exact lesion localization. Therefore, a coexistence of131I-positive/FDG-negative,131I-negative/FDG-positive and131I-positive/FDG-positive malignant tissue can be assumed in these patients. A higher correlation of FDG PET was observed with hexakis (2-methoxyisobutylisonitrile) technetium-99m (I) (MIBI) scintigraphy (performed in 20 cases) than with WBS. In highly differentiated tumours131I scintigraphy had a high sensitivity, whereas in poorly differentiated carcinomas FDG PET was superior. The clinical use of FDG PET can be recommended in all cases of suspected or proven recurrence and/or metastases of differentiated thyroid cancer and is particularly useful in cases with elevated serum thyroglobulin levels and negative WBS.

Pathological Regional Cerebral Blood Flow in Opiate-Dependent Patients during Withdrawal: A HMPAO-SPECT Study

The aims of the present study were to investigate regional cerebral blood flow (rCBF) in heroin-dependent patients during withdrawal and to assess the relation between these changes and duration of heroin consumption and withdrawal data. The rCBF was measured using brain SPECT with 99mTc-HMPAO in 16 heroin-dependent patients during heroin withdrawal. Thirteen patients received levomethadone at the time of the SPECT scans. The images were analyzed both visually and quantitatively. A total of 21 hypoperfused brain regions were observed in 11 of the 16 patients. The temporal lobes were the most affected area, hypoperfusions of the right and left temporal lobe were observed in 5 and 5 patients, respectively. Three of the patients had a hypoperfusion of the right frontal lobe, 2 patients showed perfusion defects in the left frontal lobe, right parietal lobe and left parietal lobe. The results of the quantitative assessments of the rCBF were consistent with the results of the qualitative findings. The stepwise regression analysis showed a significant positive correlation (r = 0.54) between the dose of levomethadone at the time of the SPECT scan and the rCBF of the right parietal lobe. Other significant correlations between clinical data and rCBF were not found. The present results suggest brain perfusion abnormalities during heroin withdrawal in heroin-dependent patients, which are not due to the conditions of withdrawal.

Temporal lobe dysfunction and correlation of regional cerebral blood flow abnormalities with psychopathology in schizophrenia and major depression: A study with single photon emission computed tomography

Studies of regional cerebral blood flow in both schizophrenic and depressed patients have yielded contradictory findings. Single photon emission computed tomography (SPECT) was used to compare brain-perfusion patterns in 17 patients with schizophrenia and 12 patients with major depression and to evaluate the relationship of the findings to psychopathology. The images were analyzed both visually and quantitatively. Twelve of the 17 schizophrenic patients and 8 of the 12 depressed patients showed a pathological blood flow pattern. Hypoperfusion of the left temporal lobe was observed in seven of the schizophrenic and five of the depressed patients. Five of the schizophrenic patients also had a hypoperfusion of the left frontal lobe. Separation of both diagnostic cohorts in two subgroups with pathological and normal cerebral blood flow patterns revealed significantly higher levels of symptomatology in the group with hypoperfusion in the SPECT image. The analysis of different cerebral regions revealed statistically significant temporal hypoperfusion was significantly related to positive symptoms in schizophrenia. Our data suggest that left-sided temporal lobe dysfunction is related both to schizophrenia and major depression. The localization of hypoperfusion seems to be associated with the type of psychopathology (positive vs. negative symptoms in schizophrenia). Thus, the results support the model of paralimbic and prefrontal dysfunction in both diseases.

The transsylvian approach is "minimally invasive" but not "atraumatic"

OBJECTIVE In light of the competition between microneurosurgery and alternative methods such as stereotactic radiosurgery, we tested the hypothesis that changes in the cerebral circulation after microneurosurgery are common among patients without evidence of cerebrovascular or neoplastic disease. METHODS Blood flow velocities (BFVs) were recorded with transcranial Doppler ultrasonography, before surgery and every other day after surgery, for a group of 50 patients who underwent transsylvian selective amygdalohippocampectomies for treatment of hippocampal sclerosis. Hexamethylpropylene amine oxime-single-photon emission computed tomographic testing, including acetazolamide testing of cerebrovascular reactivity, was performed during the second postoperative week for 20 of the 50 patients. RESULTS BFVs in basal arteries ipsilateral to the surgical approach increased significantly (P < 0.001) from preoperative baseline values of approximately 52 ± 13 cm/s (mean ± standard deviation) to values of approximately 86 ± 27 cm/s on postoperative Day 3 and reached their maximal values of approximately 115 ± 37 cm/s after a median of 7 days. BFVs in contralateral vessels exhibited a similar but somewhat attenuated pattern. Hexamethylpropylene amine oxime-single-photon emission computed tomography demonstrated ipsilateral regions of hypoperfusion in 100.0% of the cases and contralateral hypoperfusion in 80.0%. Cerebrovascular reactivity was impaired in 83.3% of the cases ipsilaterally and in 33.3% contralaterally. CONCLUSION A significant proportion of patients who undergo microneurosurgical procedures develop bilateral alterations of their cerebral circulation. The elevations in mean BFV values represent cerebral vasospasm. Because these changes remain asymptomatic for the majority of patients, the transsylvian approach can be considered “minimally invasive” but not “atraumatic.” Alternative surgical routes and alternative treatment modalities should be investigated in a similar manner.

Posterior cerebral artery Wada test: sodium amytal distribution and functional deficits.

Abstract Inadequate sodium amytal delivery to the posterior hippocampus during the intracarotid Wada test has led to development of selective tests. Our purpose was to show the sodium amytal distribution in the posterior cerebral artery (PCA) Wada test and to relate it to functional deficits during the test. We simultaneously injected 80 mg sodium amytal and 14.8 MBq 99 mTc-hexamethylpropyleneamine oxime (HMPAO) into the P2-segment of the PCA in 14 patients with temporal lobe epilepsy. To show the skull, we injected 116 MBq 99 mTc-HDP intravenously. Sodium amytal distribution was determined by high-resolution single-photon emission computed tomography (SPECT). In all patients, HMPAO was distributed throughout the parahippocampal gyrus and hippocampus; it was also seen in the occipital lobe in all cases and in the thalamus in 11. Eleven patients were awake and cooperative; one was slightly uncooperative due to speech comprehension difficulties and perseveration. All patients showed contralateral hemianopia during the test. Four patients had nominal dysphasia for 1–3 min. None developed motor deficits or had permanent neurological deficits. Neurological deficits due to inactivation of extrahippocampal areas thus do not grossly interfere with neuropsychological testing during the test.

Selective Middle Cerebral Artery Wada Tests as a Part of Presurgical Evaluation in Patients with Drug-resistant Epilepsies

Summary:  Purpose: To analyze the role of selective middle cerebral artery (MCA) Wada tests in the presurgical workup of patients with drug‐resistant focal epilepsies.

SATSCOM—Selective Amobarbital Test Intraarterial SPECT Coregistered to MRI: Description of a Method Assessing Selective Perfusion

For evaluation of potential functional deficits, an intraarterial amobarbital test is performed prior to neurosurgical or neuroradiological interventions. To visualize individual amobarbital perfusion patterns, simultaneous injection of (99m)Tc-HMPAO was performed previously. The present study describes for the first time a method of coregistration of intraarterial SPECT during selective amobarbital test to MRI. Three patients undergoing selective amobarbital test of the posterior cerebral artery were included. SATSCOM (Selective amobarbital test intraarterial SPECT coregistered to MRI) was performed by skull extraction in SPECT and MRI followed by surface matching. In all three patients, SATSCOM revealed accurate matching results. With this functional-anatomical mapping, suppression of higher cortical functions can be correlated to anatomical regions. Furthermore, a more precise mapping of amobarbital effect improves planning invasive interventions, particularly those close to eloquent areas.

Case Report: Regional Cerebral Hypoperfusion Induced by Ventricular Tachycardia – Short-term Hippocampal Hypoperfusion and its Potential Relationship to Selective Neuronal Damage

AbstractBackground: Focussing on regional cerebral hypoperfusion during hemodynamically stable, but borderline hypotensive, sustained ventricular tachycardia (VT) experimental studies show (1) a reduction of cerebral blood flow (CBF) during tachyarrhythmias in contrast to the concept of CBF autoregulation, (2) a mediation of hypoperfusion by neuronal and humoral mechanisms, and (3) an involvment of microcirculation due to an ischemic stress response of the cerebral tissue. The clinical relevance of these observations remains still unclear. Case reports: Two patients with coronary artery disease, left ventricular dysfunction and sustained monomorphic VT underwent electrophysiological study. VT was induced and the tracer 99mTc-HMPAO was injected after 3 minutes of ongoing VT. Regional CBF during this life threatening arrhythmia was determined with brain SPECT. A scanning protocol was performed after termination of VT. The measurements were repeated at baseline during normofrequent sinus rhythm (SR) one week later. CBF during SR was significantly reduced in the temporal lobe in comparison to the conditions during stable VT, particularly in the left hippocampus. Conclusion: The reduction of hippocampal CBF due to cerebrovascular vasoconstriction and neuronal reflex mechanism previously observed in experiments during stable, sustained VT can be confirmed in a clinical scenario by high resolution 99mTc-HMPAO brain SPECT. This supports the hypothesis that repetitive stable VT can play a role in the pathophysiology of cerebrovascular insufficiency. Further clinical studies are needed to analyze the impact of tachyarrhythmias on cognitive and mnemic function.

Interventional brain SPECT—A review

Brain SPECT with HMPAO or ECD has—due to its short accumulation period—a rather high time resolution of approx. 60 sec. Compared to isopropyl amphetamine (I-123) and FDG-PET, shortlasting interventions may be evaluated by SPECT. Usually, a two-step approach is used, injecting one third of the dose under baseline conditions and two thirds during intervention. The first study is then subtracted from the second study, resulting in a “difference” image which allows to calculate the effect of the intervention. These interventional procedures may include drug, mechanical, and mental intervention as well as ictal, blood pressure and receptor intervention. Moreover, the difference of pCO2 after hyperventilation or hypoventilation may also be used as a stimulus. The above mentioned procedures are described in detail.

Funktionelle Inaktivierung des Hippokampus im intrakarotidalen Wada-Test

ZusammenfassungIn einer prospektiven Studie untersuchten wir die Amobarbitalverteilung im Hippokampus während des intrakarotidalen Wada-Tests. Hierzu wurden 200 mg Amobarbital zusammen mit 37 MBq Tc-99m-HMPAO selektiv in die Arteria carotis interna bei 45 Hemisphären von 27 Patienten injiziert.Im anschließend angefertigten hochauflösenden Einzelphotonen-Emissionstomogramm (SPECT) war der Hippokampus abgrenzbar. Alle Anteile des Hippokampus zeigten eine Traceranreicherung, wenn im Angiogramm ein fetaler Ursprung der Arteria cerebri posterior aus der Arteria carotis interna vorlag. Unkus und Hippokampuskopf wurden in 39/45 Hemisphären zumindest teilweise im SPECT dargestellt.Die Ergebnisse bestätigen in vivo eine überwiegende Blutversorgung des Hippokampus über Äste der Arteria cerebri posterior. Zur präoperativen Abschätzung der Risikos von Gedächtnisstörungen bei selektiver Amygdalohippokampektomie erscheint daher ein selektiver Wada-Test der Arteria cerebri posterior sinnvoll.AbstractIn this prospective study we evaluated the distribution of amobarbital sodium in the hippocampus during the intracarotidal Wada-Test. 200 mg amobarbital and 37 MBq Tc-99m-HMPAO were injected simultaneously into the internal carotid artery of 45 hemispheres of 27 patients.The hippocampus could be delineated with high resolution SPECT. In patients with a fetal origin of the posterior cerebral artery from the internal carotid artery all parts of the hippocampus showed tracer accumulation. Perfusion of at least parts of the uncus and the hippocampal head were demonstrated in 39/45 hemisphers by SPECT.The results confirm in vivo that the hippocampus is predominantly supplied by branches of the posterior cerebral artery. To evaluate the risk of memory deficits after selective amygdalohippocampectomy a selective posterior cerebral artery Wada-Test is suggested.