Visualization of pressure-dependent luxury perfusion in a patient with subacute cerebral infarction

Luxury perfusion characterized by depressed metabolism compared with CBF might be changed by decreasing cerebral perfusion pressure during the sitting position. A 77-yr-old man with subacute cerebral infarction was studied with brain X-ray computed tomography (CT), raise-up test with^99mTc-d,1-hexamethylpropyleneamine oxime (HMPAO) brain single photon emission tomography (SPECT) and positron emission tomography (PET). Brain X-ray CT revealed a low-density area in the left middle cerebral artery (MCA) anterior area. Raise-up^99mTc-HMPAO brain SPECT revealed decreased uptake in the left MCA anterior area in the sitting position and subsequent supine^99mTc-HMPAO brain SPECT revealed hot accumulation there. PET study in the supine position demonstrated some differences between CBF and the cerebral metabolic rate for oxygen in the left MCA anterior area, indicating luxury perfusion. CBF in the area of luxury perfusion might be decreased during the sitting or standing position and increased during the supine position by dysautoregulation of the cerebral vessels in the luxury perfusion during the subacute infarct.     

“Luxury perfusion” with99mTc-HMPAO and123I-IMP SPECT imaging during the subacute phase of stroke

To compare the merits of¹²³I-isopropyl-iodoam-phetamine (¹²³I-IMP) and^99mTc-HMPAO in showing abnormal brain uptake distribution during cerebral ischemia, we studied ten patients during the subacute phase of their stroke, a period where metabolism and blood flow are frequently uncoupled. SPECT imaging was performed using both radiopharmaceuticals in the 10 patients from 48 h to 4 weeks after onset of symptoms. Two patients out of the 10 had similar defects with¹²³I-IMP and^99mTc-HMPAO SPECT, the location of the defects corresponding to the area of infarction observed on CT. Six patients had normal^99mTc-HMPAO SPECT and abnormal¹²³I-IMP SPECT with defects in the area of infarction shown by CT. The remaining 2 patients had hyperactive abnormalities on^99mTc-HMPAO in areas corresponding to defects on the¹²³I-IMP images. Two of the patients with SPECT mismatches were studied again more than 1 month after onset. On reexamination,^99mTc-HMPAO SPECT which was previously normal or hyperactive became hypoactive with a focal area of decreased activity corresponding to the defect on¹²³I-IMP. Crossed cerebellar diaschisis was found in 7 patients with^99mTc-HMPAO and was absent for both¹²³I-IMP and^99mTc-HMPAO in 3. We suggest that SPECT with⁹⁹mTc-HMPAO could show transient hyperemia not demonstrated by¹²³I-IMP whereas in some cases cerebral infarction would be more difficult to demonstrate with^99mTc-HMPAO than with¹²³I-IMP. SPECT with both tracers is recommended to follow the evolution of strokes in terms of regional cerebral blood flow and tissue metabolism.     

Required time delay from <Superscript>99m</Superscript>Tc-HMPAO injection to SPECT data acquisition: healthy subjects and patients with rCBF pattern

Purpose  Functional brain ^99mTc-HMPAO single-photon emission computed tomography (SPECT) is a useful diagnostic tool for assessment of regional cerebral blood flow, particularly in dementia, cerebrovascular disease and epilepsy. Currently, the European and American Association of Nuclear Medicine Procedure Guidelines for Brain Perfusion SPET using ^99mTc-labeled Radiopharmaceuticals recommend a time delay of 90 min between injection of ^99mTc-HMPAO and data acquisition. This time delay is difficult to comply within the daily routine and present a problem, particularly with the elderly or demented patients. This study investigates in patients with perfusion deficits and in healthy subjects if the quality of the SPECT image is affected by lowering the time delay between ^99mTc-HMPAO injection and data acquisition to 30 or 60 min. Methods  Thirty-seven healthy subjects (17 females; mean age 65; range 42–84 years) with normal cerebral blood flow distribution and 31 patients (17 females; mean age 67; range 38–84) with reduced rCBF distribution were included. Images were obtained with a three-headed Philips IRIX SPECT scanner with high-resolution collimators. The healthy subjects were scanned 30, 60 and 90 min after ^99mTc-HMPAO injection, and the patients were scanned 30 and 90 or 60 and 90 min after ^99mTc-HMPAO injection. For evaluation of differences between the images obtained at various time points after injection, two different methods were used. The z-map method was used to subtract images from each other prior to visual inspection. In addition, principal component analysis was used as a quantitative analysis of the similarity of the images. Results  Visual inspection of the subtracted images (30 or 60 versus 90 min) revealed that there was no spatial bias. Quantitatively, the average proportion of the total variance explained by the first principal component was 99.5% (range 98.9–99.6) for the healthy subjects and 99.4% (range 98.5–99.8) for the patients. Conclusion  The time delay from injection of ^99mTc-HMPAO to the start of the SPECT data acquisition can be reduced from 90 to 30 min without any significant impact on the quality of the acquired image.     

The clinical utility of 99<Superscript>m</Superscript>Tc-HMPAO SPECT in Fahr’s disease

Fahr's disease is a rare neurodegenerative syndrome, characterized by massive symmetrical intracerebral calcifications of the basal ganglia, dentate nuclei of the cerebellum, and the adjacent parenchyma. Computerized tomography (CT) is considerably more sensitive to detect these intracranial calcifications than other imaging modalities. The clinical, CT scan, and 99(m)Tc-D,L-hexamethylpropylene amine oxime (99(m)Tc-HMPAO) brain perfusion single-photon emission computerized tomography (SPECT) findings in a 42-year-old woman with Fahr's disease are reported, and the clinical utility of 99(m)Tc-HMPAO SPECT findings in Fahr's disease is discussed in this article. In conclusion, 99(m)Tc-HMPAO brain perfusion SPECT seems to be useful in the clinical approach to Fahr's disease, and may provide more specific and clinically relevant information when compared with anatomical imaging.     

Postoperative assessment of cerebral blood flow in subarachnoid haemorrhage by means of99mTc-HMPAO tomography

Regional hypoperfusion is a very frequent complication of subarachnoid haemorrhage (SAH), being related to vasospasm in the majority of cases. Twenty-six patients who were admitted for SAH underwent follow-up with technetium-99m hexamethylpropylene amine oxime single photon emission tomography (SPECT) 3 and 8 days after surgery. Fifteen patients of these had one more examination 15 days after surgery. The degree of hypoperfusion was quantified using an index of asymmetry which allow the comparison of two symmetrical regions of interest (ROIs) on the transaxial slice which presented the greatest perfusion defect. Comparison of CT data, transcranial Doppler data and clinical signs with the perfusion as quantified by^99mTc-HMPAO SPECT indicates that a difference in counts of less than 10% between the two symmetrical ROIs is of no diagnostic value. Follow-up of the brain perfusion clearly shows that the most pronounced hypoperfusion was observed just after surgery, with progressive normalization at 8 and 15 days after surgery.^99mTc-HMPAO SPECT performed 8 days after surgery allows prediction of the clinical outcome. For these reasons,^99mTc-HMPAO SPECT, which is the only method for follow-up of cerebral perfusion in routine clinical practice, should be the first examination to be performed after surgery in patients with SAH.     

Perfusion MRI before and after acetazolamide administration for assessment of cerebrovascular reserve capacity in patients with symptomatic internal carotid artery (ICA) occlusion: comparison with <Superscript>99m</Superscript>Tc-ECD SPECT

Introduction Impaired cerebral vascular reserve (CVR) in patients with symptomatic internal carotid artery (ICA) occlusion is regarded as a possible indication for performing extra-/intracranial (EC/IC) bypass surgery. As perfusion MR imaging (MRI) can demonstrate cerebral haemodynamics at capillary level, our hypothesis was that perfusion MRI could be used in these patients for the evaluation of CVR following acetazolamide challenge in a similar way to single photon emission CT (SPECT) and might provide additional information. Methods Enrolled in the study were 12 patients (mean age 61.3 years; 11 male, 1 female) with symptomatic unilateral ICA occlusion proven by angiography. Both perfusion MRI and 99m-technetium-ethyl-cysteinate dimer (^99mTc-ECD) SPECT were performed before and after injection of acetazolamide (Diamox ,1000 mg i.v.). CVR parameters including regional cerebral blood flow (rCBF) and volume (rCBV), and mean transit times (MTT) were measured by perfusion MRI. Results The patients with impaired CVR proven by SPECT (n = 9) had a negative mean rCBF increment (−46.52%), negative rCBV increment (−13.5%) and delayed MTT (mean +2.98 s), respectively, on the occluded side (Student’s t-test all P < 0.05). The patients with sufficient CVR (n = 3) had a mean rCBF increment of 1.2%, a decrement of rCBV of 10.46%, and a mean MTT shortening of 0.27 s following the acetazolamide injection. Conclusions Perfusion MRI before and after acetazolamide administration compares favourably with ^99mTc-ECD SPECT for the detection of impaired CVR. The impact that perfusion MRI studies (before and after acetazolamide administration) might have on the treatment decision in patients with ICA occlusion has yet to be determined by a prospective study. The first and second author contributed equally to this study.     

Agreement and disagreement between contrast-enhanced magnetic resonance imaging and nuclear imaging for assessment of myocardial viability

Purpose  The purpose of this study was to compare contrast-enhanced MRI and nuclear imaging with ^99mTc-tetrofosmin and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) single photon emission computed tomography (SPECT) for assessment of myocardial viability. Methods  Included in the study were 60 patients with severe ischaemic left ventricular (LV) dysfunction who underwent contrast-enhanced MRI, ^99mTc-tetrofosmin and ¹⁸F-FDG SPECT. Myocardial segments were assigned a wall motion score from 0 (normokinesia) to 4 (dyskinesia) and a scar score from 0 (no scar) to 4 (76–100% transmural extent). Furthermore, ^99mTc-tetrofosmin and ¹⁸F-FDG segmental tracer uptake was categorized from 0 (tracer activity >75%) to 3 (tracer activity <25%). Dysfunctional segments were classified into viability patterns on SPECT: normal perfusion/¹⁸F-FDG uptake, perfusion/¹⁸F-FDG mismatch, and mild or severe perfusion/¹⁸F-FDG match. Results  Minimal scar tissue was observed on contrast-enhanced MRI (scar score 0.4±0.8) in segments with normal perfusion/¹⁸F-FDG uptake, whereas extensive scar tissue (scar score 3.1±1.0) was noted in segments with severe perfusion/¹⁸F-FDG match (p < 0.001). High agreement (91%) for viability assessment between contrast-enhanced MRI and nuclear imaging was observed in segments without scar tissue on contrast-enhanced MRI as well as in segments with transmural scar tissue (83%). Of interest, disagreement was observed in segments with subendocardial scar tissue on contrast-enhanced MRI. Conclusion  Agreement between contrast-enhanced MRI and nuclear imaging for assessment of viability was high in segments without scar tissue and in segments with transmural scar tissue on contrast-enhanced MRI. However, evident disagreement was observed in segments with subendocardial scar tissue on contrast-enhanced MRI, illustrating that the nonenhanced epicardial rim can contain either normal or ischaemically jeopardized myocardium.     

Brain SPECT imaging in temporal lobe epilepsy

Summary Temporal lobe epilepsy is diagnosed by clinical symptoms and signs and by localization of an epileptogenic focus. A brain SPECT study of two patients with temporal lobe epilepsy, using^99mTc-HMPAO, was used to demonstrate a perfusion abnormality in the temporal lobe, while brain CT and MRI were non-contributory. The electroencephalogram, though abnormal, did not localize the diseased area. The potential role of the SPECT study in diagnosis and localization of temporal lobe epilepsy is discussed.     

Clinical experience with Tc-99m HM-PAO high resolution SPECT of the brain in patients with cerebrovascular accidents

In order to evaluate the diagnostic contribution of brain SPECT imaging with ^99mTc-HMPAO in cerebrovascular disease, we examined 92 stroke cases (144 lesions), 2 hematoma cases and 30 cases with transient neurologic symptoms. Abnormal tracer distribution is visible as zones of either hypoactivity or hyperactivity (border zone hyperemia or luxury perfusion). Remote vascularization changes could also be found (crossed cerebellar diaschisis or ipsilateral cortical perfusion reduction in thalamic or capsula interna lesions). Both X-ray CT and blood flow SPECT have comparable sensitivity in the exploration of cerebral infarction, with detection in, respectively, 89.5% and 87.5% of the lesions. False negative scintitomographic images are frequently recorded in small lacunar infarcts within the basal ganglia and white matter (capsula interna). Some early infarcts and asymmetry of brain perfusion in patients with transient neurologic symptoms are frequently not detected by CT. An additional advantage of blood flow SPECT is its ability to visualize remote blood flow changes and the changing pattern of vascularization of ischemic lesions and their surrounding areas including hyperemia.     

Regional differences between <Superscript>99m</Superscript>Tc-ECD and <Superscript>99m</Superscript>Tc-HMPAO SPET in perfusion changes with age and gender in healthy adults

A number of studies using single-photon emission tomography (SPET) have shown perfusion changes with age in several cortical and subcortical areas, which might distort the results of perfusion imaging studies of neuropsychiatric disorders. Technetium-99m labelled ethyl cysteinate dimer (ECD) and hexamethylpropylene amine oxime (HMPAO) are both used as markers of cerebral perfusion, but have different pharmacokinetics and retention patterns. The aim of this study was to determine whether age and gender effects on perfusion SPET differ depending on whether ^99mTc-HMPAO or ^99mTc-ECD is used. Forty-five subjects (20 male and 25 female, mean age 52.8±6.6 years) were assigned to ^99mTc-HMPAO SPET (HMPAO group), and 39 subjects (24 male and 15 female, mean age 52.6±6.7 years) to ^99mTc-ECD SPET (ECD group). SPET images were obtained about 10 min after intravenous injection of approximately 800 MBq ^99mTc-HMPAO or ^99mTc-ECD using the same SPET scanner. Three-dimensional volumetric magnetic resonance imaging was performed to as7sess morphological changes in the grey matter. All image processing and statistical analyses were performed using SPM99 software. An area in the right anterior frontal lobe showed an increase in perfusion with age only in the HMPAO group, whereas areas in the bilateral retrosplenial cortex showed decreases in perfusion with age only in the ECD group; neither group showed corresponding changes in the grey matter. The present study shows that different effects of age on perfusion are observed depending on whether ^99mTc-HMPAO and ^99mTc-ECD is used. This suggests that the results of perfusion SPET are differently confounded depending on the tracer used, and that perfusion SPET with these tracers has limitations when used in research on subtle perfusion changes.     

Regional cerebral blood flow in patients with carbon monoxide intoxication

Rationale and objectives

Early detection of regional cerebral anomalies in acute carbon monoxide (CO) poisoning by ^99mTc-hexamethylprophylene amine oxime (HMPAO) brain single photon emission computed tomography (SPECT) imaging has been reported previously. However, SPECT findings varied in these studies because of their small population sizes. In this study, we included 96 patients with acute CO intoxication and analyzed the regional perfusion changes in these patients by means of HMPAO brain SPECT.

Materials and methods

Ninety-six patients, aged 4?C80?years (mean age 32?years) with acute CO intoxication diagnosed by our emergency department were included in this study. Exclusion criteria included previous cerebrovascular diseases, brain injury, brain surgery and any known neurological and psychological disorders. All patients underwent a brain scan using a dual-head camera and fan-beam collimator 90?C120?min after injection of ^99mTc-HMPAO. Brain SPECT images were obtained for interpretation.

Results

Our data suggested that 79 of the 96 patients (82.3?%) had abnormal HMPAO brain images. The predominant site of disease was basal ganglia (52/96?=?54.2?%), followed by temporal lobe (48/96?=?50.0?%), parietal lobe (44/96?=?45.8?%), frontal lobe (30/96?=?31.2?%), occipital lobe (21/96?=?21.9?%) and thalamus (8/96?=?8.3?%). No patients with acute CO intoxication had perfusion abnormalities in the cerebellum. In addition, there was no significant difference in serum COHb levels between patients with abnormal and normal HMPAO brain images.

Conclusion

^99mTc-HMPAO SPECT imaging is a useful tool to detect functional brain injury in acute CO intoxication.     

Parametric Cerebrovascular Reserve Images Using Acetazolamide 99mTc-HMPAO SPECT: A Feasibility Study of Quantitative Assessment

Purpose

Basal/acetazolamide stress ^99mTc-HMPAO single-photon emission computed tomography (SPECT) has been widely used for evaluation of hemodynamics; however, qualitative and subjective visual assessment of cerebrovascular reserve (CVR) has been performed in clinical settings. The aim of this study was to generate parametric CVR images and evaluate its feasibility of quantification.

Methods

Basal/acetazolamide stress ^99mTc-HMPAO SPECT data from 17 patients who underwent bypass surgery or percutaneous transluminal angioplasty were used. Spatial normalization was performed and parametric CVR images were generated using relative CVR (rCVR) of each voxel proportional to CVR of the whole brain. Binary parametric maps to show area of relatively reduced CVR were generated also using threshold of rCVR < 90 %. We calculated rCVR of internal carotid artery (ICA) using the parametric CVR images and probabilistic maps for ICA territory. Pre- and postprocedural parametric CVR images were obtained and quantitative rCVRs were compared. The rCVRs were evaluated according to visual grades for regional decreased CVR.

Results

Postprocedural rCVR obtained from parametric CVR images increased significantly from preprocedural rCVR. The rCVR was significantly correlated with visual grades of reduced CVR for each side of ICA territories.

Conclusions

We generated parametric CVR images for basal/acetazolamide stress ^99mTc-HMPAO SPECT. As a quantitative measurement, rCVR obtained from the parametric image was feasibly assessed hemodynamic abnormalities with preserved anatomical information.     

An evaluation of99mTc-HMPAO uptake in cerebral gliomas —a comparison with X-ray CT

Nineteen patients with biopsy-proven cerebral gliomas were studied with^99mTc-HMPAO single photon emission tomography (SPELT) imaging and X-ray computed tomography (CT). The uptake of^99mTc-HMPAO was correlated with tumour size and morphology as shown by X-ray CT, and overall patient survival. It appears that uptake of^99mTc-HMPAO is associated with larger, ill-defined tumours and was an adverse factor in patient survival. In those tumours with normal or increased uptake,^99mTc-HMPAO imaging is useful in distinguishing the tumour margin from surrounding oedema.     

<Superscript>99m</Superscript>Tc-ECD brain perfusion SPECT in hyperalgesic fibromyalgia

Purpose Neuro-imaging studies with ^99mTc-HMPAO SPECT in fibromyalgia (FM) patients have reported only limited subcortical hypoperfusion. ^99mTc-ECD SPECT is known to provide better evaluation of areas of high cerebral blood flow and regional metabolic rate. We evaluated a homogeneous group of hyperalgesic patients with FM using ^99mTc-ECD SPECT. The aim of this study was to investigate brain processing associated with spontaneous pain in FM patients. Methods Eighteen hyperalgesic FM women (mean age 49 years, range 25–63 years; American College of Rheumatology criteria) and ten healthy women matched for age were enrolled in the study. A voxel-by-voxel group analysis was performed using SPM2 (p<0.05, corrected for multiple comparisons). Visual Analogue Scale score for pain was 82±4 at the time of the SPECT study. Results Compared with control subjects, we observed individual brain SPECT abnormalities in FM patients, confirmed by SPM2 analysis, with hyperperfusion of the somatosensory cortex and hypoperfusion of the frontal, cingulate, medial temporal and cerebellar cortices. Conclusion In the present study, performed without noxious stimuli in hyperalgesic FM patients, we found significant hyperperfusion in regions of the brain known to be involved in the sensory dimension of pain processing and significant hypoperfusion in areas assumed to be associated with the affective-attentional dimension. As current pharmacological and non-pharmacological therapies act differently on the two components of pain, we hypothesise that SPECT could be a valuable and readily available tool to guide individual therapeutic strategy and provide objective follow-up of pain processing recovery under treatment.     

A technetium-99m hexamethylpropylene amine oxime brain single-photon emission tomography study in adolescent patients with major depressive disorder

We have not encountered any brain single-photon emission tomography (SPET) study performed in adolescent depressed patients in the literature. Therefore, we used technetium-99m hexamethylpropylene amine oxime (^99mTc-HMPAO) brain SPET in adolescent patients with major depressive disorder (MDD) to examine the possible changes in cerebral perfusion and the possible association between perfusion indices and clinical variables. Fourteen adolescent out-patients (nine females, five males; mean±SD age: 13.11±1.43 years; range: 11–15 years) fulfilling the DSM-IV criteria for MDD and 11 age-matched healthy control subjects (six females, five males; mean±SD age: 13.80±1.60 years; range: 12–15 years) were included in the study. ⁹⁹Tc-HMPAO brain SPET was performed twice in the patient group and once in the control group. The first SPET investigation was performed under non-medicated conditions and the second was performed after depressive symptoms had subsided. A relative perfusion index (PI) was calculated as the ratio of regional cortical activity to the whole brain activity. We found significant differences between the PI values of the untreated depressed patients and those of the controls, indicating relatively reduced perfusion in the left anterofrontal and left temporal cortical areas. No significant differences in regional PI values were found between the remitted depressed patients and the controls. Our study suggests that adolescent patients with MDD may have regional cerebral blood flow deficits in frontal regions and a greater anterofrontal right-left perfusion asymmetry compared with normal subjects. The fact that these abnormalities in perfusion indices have a trend toward normal values with symptomatic improvement suggests that they may be state-dependent markers for adolescent MDD. Received 11 January and in revised form 11 February 1998     

Combined study of99mTc-HMPAO SPECT and computerized electroencephalographic topography (CET) in patients with medically refractory complex partial epilepsy

For successful surgery for drug-resistant partial epilepsy the site of the seizure focus needs to be known exactly. The purpose of this study was to compare the evaluation of the regional cerebral blood flow (rCBF) (localization and degree of disturbances) by^99mTc-hexamethylpropylene-amineoxime (HMPAO) single photon emission computed tomography (SPECT) with computerized electroencephalographic topography (CET) and transmission computed X-ray tomography (CT) in partial epilepsy. The study included 20 patients with medically refractory complex partial seizures. Of the 20 patients included, 15 were studied interictally, four ictally and one in both states, interictally and ictally. ^99mTc-HMPAO SPECT detected rCBF changes in 95% of the patients. Interictal studies demonstrated focal areas of hypoperfusion in 93% of the patients. Ictal studies demonstrated an area of hyperperfusion in all patients. Blood flow disturbances in deeper structures of the brain, such as basal ganglia, could be detected. The areas with abnormal^99mTc-HMPAO uptake were concordant, in localization, with CET in 85% of the patients. Abnormal data with CT scans were found in only 45% of the patients. Focal lesions were found in 20% of the patients by CT scans. ^99mTc-HMPAO SPECT combined with CET may be a useful screening procedure prior to referral for invasive diagnostic procedures in future management of patients with medically refractory complex partial seizures.     

Neuroradiological findings in primary progressive aphasia: CT,MRI and cerebral perfusion SPECT

Primary progressive aphasia (PPA) is defined as progressive decline in language for 2 or more years with preservation of activities of daily living and general cognitive functions. Whereas the clinical features of this syndrome have been well documented, the neuroradiological findings have not been studied systematically. We studied 13 patients with PPA retrospectively: 10 underwent CT, 12 MRI and 12 cerebral perfusion studies using^99mTc-HMPAO SPECT. CT and MR images were scored for focal atrophy by two independent assessors. Initial qualitative assessment of SPECT images was confirmed by quantitative analysis. CT was normal in 5 patients. Focal atrophy, affecting predominantly the left temporal lobe, was seen in 4 of 10 patients on CT, and 10 of 12 on MRI. Atrophy was localised primarily to the superior and middle temporal gyri on MRI. All 12 patients who underwent SPECT had unilateral temporal lobe perfusion defects, in 2 patients of whom MRI was normal. CT is relatively insensitive to focal abnormalities in PPA; MRI and SPECT are the imaging modalities of choice. MRI allows accurate, specific localisation of atrophy within the temporal neocortex. SPECT may reveal a functional decrease in cerebral perfusion prior to establishment of structural change.     

RCBF-quantification with 99mTc-HMPAO-SPECT: Theory and first results

The activity concentrations of ^99mTc-HMPAO in brain after intravenous injection were evaluated in 25 patients using SPECT. With additional first pass studies of heart and brain with the short lived isotope ^195mAu, the cardiac output and the mean cerebral transit times of the patients were measured a short time before the HMPAO injection. The time dependence of ^99mTc-HMPAO activity in the brain was registered during the first 5 min after injection over both hemispheres. Using a simplified three compartment model it was possible to calculate the mean retention fraction of HMPAO in brain from the time activity curves. It could be shown that the regional cerebral blood flow in ml/min per 100 g can be calculated from the activity concentration of HMPAO in the brain, the cardiac output and the retention fraction. In 15 of the 25 cases the rCBF was measured using the planar ¹³³Xe inhalation method as a reference. We found a significant correlation between the mean hemisphere CBF from our method and the mean hemisphere grey matter CBF from the Xenon method with a correlation coefficient of 0.73.     

Effect of lamotrigine on cerebral blood flow in patients with idiopathic generalised epilepsy

Purpose The purpose of this study was to investigate the effects of the new anti-epileptic drug, lamotrigine, on cerebral blood flow by performing ^99mTc-ethylcysteinate dimer (ECD) single-photon emission computed tomography (SPECT) before and after medication in patients with drug-naive idiopathic generalised epilepsy.Methods Interictal ^99mTc-ECD brain SPECT was performed before drug treatment started and then repeated after lamotrigine medication for 4–5 months in 30 patients with generalised epilepsy (M/F=14/16, 19.3±3.4 years). Seizure types were generalised tonic-clonic seizure in 23 patients and myoclonic seizures in seven. The mean lamotrigine dose used was 214.1±29.1 mg/day. For SPM analysis, all SPECT images were spatially normalised to the standard SPECT template and then smoothed using a 12-mm full-width at half-maximum Gaussian kernel. The paired t test was used to compare pre- and post-lamotrigine SPECT images.Results SPM analysis of pre- and post-lamotrigine brain SPECT images showed decreased perfusion in bilateral dorsomedial nuclei of thalami, bilateral uncus, right amygdala, left subcallosal gyrus, right superior and inferior frontal gyri, right precentral gyrus, bilateral superior and inferior temporal gyri and brainstem (pons, medulla) after lamotrigine medication at a false discovery rate-corrected p<0.05. No brain region showed increased perfusion after lamotrigine administration.Conclusion Our study demonstrates for the first time the effect of lamotrigine on interictal cerebral perfusion in drug-naive idiopathic generalised epilepsy patients. In summary, lamotrigine medication was found to reduce perfusion in cortico-thalamo-limbic areas, the orbitofrontal cortex, and brainstem.     

Brain MRI and SPECT in the diagnosis of early neurological involvement in Wilson’s disease

Purpose To evaluate the impact of brain MRI and single-photon emission computed tomography (SPECT) in early detection of central nervous system abnormalities in patients affected by Wilson’s disease (WD) with or without neurological involvement. Methods Out of 25 consecutive WD patients, 13 showed hepatic involvement, ten hepatic and neurological manifestations, and twp hepatic, neurological, and psychiatric symptoms, including mainly movement disorders, major depression, and psychosis. Twenty-four healthy, age–gender matched subjects served as controls. All patients underwent brain MRI and ^99mTc-ethyl-cysteinate dimer (ECD) SPECT before starting specific therapy. Voxel-by-voxel analyses were performed using statistical parametric mapping to compare differences in ^99mTc-ECD brain uptake between the two groups. Results Brain MRI showed T2-weighted hyperintensities in seven patients (28%), six of whom were affected by hepatic and neurological forms. Brain perfusion SPECT showed pathological data in 19 patients (76%), revealing diffuse or focal hypoperfusion in superior frontal (Brodmann area (BA) 6), prefrontal (BA 9), parietal (BA 40), and occipital (BA 18, BA 39) cortices in temporal gyri (BA 37, BA 21) and in caudatus and putamen. Moreover, hepatic involvement was detected in nine subjects; eight presented both hepatic and neurological signs, while two exhibited WD-correlated hepatic, neurological, and psychiatric alterations. All but one patient with abnormal MRI matched with abnormal ECD SPECT. Pathologic MRI findings were obtained in six out of ten patients with hepatic and neurological involvement while abnormal ECD SPECT was revealed in eight patients. Both patients with hepatic, neurological, and psychiatric involvement displayed abnormal ECD SPECT and one displayed an altered MRI. Discussion These findings suggest that ECD SPECT might be useful in detecting early brain damage in WD, not only in the perspective of assessing and treating motor impairment but also in evaluating better the less investigated disorders in the cognitive domain.