Evolution of technetium-99m-HMPAO SPECT and brain mapping in a patient presenting with echolalia and palilalia.

A 78-yr-old woman presented with transient echolalia and palilalia. She had suffered from Parkinson's disease for 2 yr. Routine laboratory examination showed hypotonic hyponatremia, but was otherwise unremarkable. Brain mapping revealed a bifrontal delta focus, more pronounced on the right. Single photon emission computed tomography (SPECT) of the brain with technetium-99m labeled d,l hexamethylpropylene-amine oxime (99mTc-HMPAO), performed during the acute episode showed relative frontoparietal hypoactivity. Brain mapping performed after disappearance of the echolalia and palilalia, which persisted only for 1 day, was normal. By contrast, SPECT findings persisted for more than 3 wk. Features of particular interest in the presented patient are the extensive defects seen on brain SPECT despite the absence of morphologic lesions, the congruent electrophysiologic changes and their temporal relationship with the clinical evolution.

Discriminative use of SPECT in frontal lobe-type dementia versus (senile) dementia of the Alzheimer's type.

UNLABELLED: Dementia of the Alzheimer's type [(S)DAT] and dementia with frontal features (FLD) are nosological entities with different prognoses and presumed pathophysiology. There is a need for noninvasive differential diagnostic tools. To evaluate whether SPECT perfusion imaging could discriminate between these neurodegenerative disorders, we performed a comparative study. METHODS: SPECT scans using 99mTc-hexamethylpropylene amine oxime (99mTc-HMPAO) of 21 patients with FLD were compared with those obtained in a group of 19 age- and severity-matched patients suffering from (S)DAT. Brain SPECT perfusion deficits were scored by visual qualitative analysis with respect to location, lateralization and severity. A total severity score of cerebral hypoperfusion (maximal value = 18) was calculated by adding all severity scores (scored between 0 and 3; 0 = no perfusion deficit; 1 = 13%-30% hypoperfusion; 2 = 30%-50%, hypoperfusion and 3 = > 50% hypoperfusion including breaching of the cortex) for right and left frontal, parietal and temporal lobes. Moreover, bifrontal hypoperfusion (Fa) was scored, yielding a value between 0 and 6 by adding the two frontal severity scores. RESULTS: No significant correlation was found between MMSE scores and total severity scores on SPECT. A statistically significant correlation was found between the Middelheim frontality score and frontal severity score. Statistically more significant bilateral hypoperfusion of the parietal lobes was found in the (S)DAT group. Conversely, bifrontal hypoperfusion was found more in the FLD group. Stepwise logistic regression analysis identified the severity of bifrontal hypoperfusion as the most significant contributing parameter to correctly classifying (S)DAT versus FLD on SPECT. The probability of predicting (S)DAT based on the SPECT scan is calculated with the following formula: [equation: see text] Using this equation, a value above 0.5 was predictive for (S)DAT and a calculated value under 0.5 was predictive for FLD. Using this model, 81% of the FLD group and 74% of the (S)DAT were correctly classified. CONCLUSION: Technetium-99m-HMPAO SPECT may help in discriminating FLD from (S)DAT. Bifrontal hypoperfusion was found to be the most powerful predictor of clinical classification. Further validation of the presented logistic regression model is warranted.

Clinical usefulness of ultrashort-lived iridium-191m from a carbon-based generator system for the evaluation of the left ventricular function.

Ultrashort-lived 191mIr (4.96 sec; 63-74 and 129 keV photons) is potentially advantageous for first-pass radionuclide angiocardiography, offering the opportunity to perform repeat studies with very low absorbed radiation dose to the patient. Left ventricular (LV) first-pass studies were performed in 72 patients with 191mIr from a new bedside 1.3 Ci (48.1 GBq) 191Os/191mIr generator system using an activated carbon support that offers high 191mIr yields (15-18%) and consistent low 191Os breakthrough (2-4 x 10(-4)%/bolus). Using a single crystal digital gamma camera, uncorrected end-diastolic counts in the left ventricular representative cycle ranged from 10 up to 30 k counts. The reproducibility of repeated LV ejection fraction (LVEF) determination at 2-min intervals in 50 patients was r = 0.97, mean diff. = 2.08 +/- 1.55 EF units. Comparison between 191mIr (80-120 mCi; 2,960-4,400 MBq) and 99mTc (20-25 mCi; 750-925 MBq) LV count rates indicates a 3 wk useful shelf life of this new generator system for cardiac studies. Iridium-191m determined LVEF correlated closely with 99mTc determined LVEF in 32 patients (r = 0.96, mean diff. = 1.87 +/- 1.23 EF units). Parametric images for LV wall motion analysis were comparable with both isotopes. We conclude that rapid, repeat, and reproducible high count rate first-pass left ventricular studies can be obtained with 191mIr from this new 191Os/191mIr generator system using a single crystal digital gamma camera.

Critical evaluation of lung scintigraphy in cystic fibrosis: study of 113 patients.

A long-term study has been performed on 285 lung perfusion scintigrams obtained from 113 patients with cystic fibrosis. Transverse and longitudinal comparisons with clinical and radiological scores, as well as retrospective analysis of the deceased patients, were the methods used in order to evaluate the importance of the scintigraphic images. It appears that lung scintigraphy is the best index of the regional lung impairment, and contributes, as does a chest radiograph, to the early detection of lung lesions, the two methods being complementary. The survival rate of CF patients reached 0.80 at 9 yr when initial scintigraphy was normal or only moderately impaired, but fell to 0.18 when severe lesions were seen on the first scintigrams.

Single photon emission computed tomography using perfusion tracers in seizure disorders.

Single photon emission computed tomography (SPECT) using perfusion tracers makes it possible to estimate regional cerebral blood flow (rCBF) and, indirectly, local brain metabolism. It may be possible to detect and follow physiopathological alterations, such as may be seen in seizure disorders. The authors review the principles of and some data on perfusion SPECT in seizure disorders, stress advantages as well as major drawbacks and add their initial experience with Tc-99m hexamethylpropyleneamine oxime (HMPAO) SPECT in febrile convulsions.

Effect of mild mental stress on solid phase gastric emptying in healthy subjects.

Radionuclide gastric emptying studies are performed in clinical routine but the possible influence of the mental state of the patient is never taken into account. We wanted to evaluate the effect of a mild psychological stress on solid phase gastric emptying in healthy young male volunteers. The standard meal consisted of a pancake (500 kJ) without additional liquid. Simultaneous dynamic acquisitions of gastric activity in anterior and posterior projection were taken during 90 min starting from the onset of the meal. Gastric emptying was evaluated three times in basal conditions and once under mental stress. Stress was induced by means of a dichotomous listening test, lasting for 30 min, starting at the end of the meal. The results of rest and stress studies were compared. Mild mental stress has a significant influence on gastric emptying. The lag phase increased from 11 +/- 3 min to 36 +/- 10 min (mean +/- S.D.) (p less than 0.005) and the gastric emptying rate from 79 +/- 13%/hour to 100 +/- 31%/hour (mean +/- S.D.) (not significant). During a stress period gastric emptying as a whole is delayed but this is mainly due to the prolongation of the lag phase. Our data also suggest that during the stress period gastric emptying is interrupted and reactivated once the stress period has ended.

Assessment of vertebral mineral content by means of a single-crystal scintillation camera.

Increasing interest in bone mass has led to dedicated commercial dual photon absorptiometry (DPA) instruments. We describe a method for the measurement of the mineral content of the lumbar spine using a scintillation camera. The most appropriate source(s) and collimator were investigated. An especially constructed arm placed the sources in the focal point of a converging collimator. Two single-peak sources, 99Tcm and 241Am, were used instead of dual-peak 153Gd source. Phantom studies showed no degradation of the results in water depths of up to 26 cm. Acquiring 10 Mcounts per image over a 300 cm2 field, a coefficient of variation (c.v.) of 1.7% was obtained. Reducing the total counts per image to 1 Mcount gave rise to a c.v. of 6.2%. Long-term measurements showed a c.v. of 1.1% for density, with a mean value of 0.98 gHa cm-2 compared to 0.90 for a commercial DPA instrument. Repeated measurements of the lumbar spine on 10 patients with a 2 week interval showed a c.v. of 5%. Comparative measurements were made between the scintillation camera and a commercial DPA instrument on six volunteers. Systematic higher results, similar to those observed with the phantom, were obtained with the scintillation camera. The reproducibility on a phantom and in patients is in the same range as commercial DPA instruments. The low cost related to the use of standard nuclear medicine equipment and to inexpensive radioactive sources represent definite advantages.

240 degrees: why not?

Single photon emission tomographic imaging of myocardial perfusion with 99Tcm-labelled agents is usually performed with single-detector gamma camera systems and 180 degrees anterior data collection. With multi-detector systems, reconstruction over 180 degrees and 360 degrees has been reported. We used a data set of normal subjects to compare both reconstruction methods. In addition, we tested an alternative approach, reconstructing data from 240 degrees acquisitions, excluding the right posterior views, which provide little myocardial information and which are responsible for a reduced signal-to-noise ratio. On the transverse slices, the known apical distortion with the 180 degrees reconstruction was not noted with the 360 degrees or 240 degrees reconstructions. Using semi-quantitative analysis of apical, mid-ventricular and basal short-axis slices, almost complete overlap was observed between the 240 degrees and 360 degrees circumferential profiles of our 20 normal volunteers, except in the inferior wall where a reduction in activity was noted. However, this finding was less pronounced with the 240 degrees than with the 180 degrees reconstruction. The frequent reduction in activity in the anterior wall was more prominent with the 180 degrees than with the 240 degrees and 360 degrees reconstructions. A 240 degrees acquisition represents a useful compromise between 180 degrees and 360 degrees imaging protocols when a single-detector device is used, allowing more homogeneous tracer distribution and a reduction in the apical distortion without material change of contrast or doubling of the acquisition time.

Performance of a single crystal digital gamma camera for first pass cardiac studies.

First pass radionuclide angiocardiography (FPRNA) has gained increasing interest because of the development of new 99Tcm-labelled perfusion agents and of new 191Os/191Irm generator systems. The aim of the study was to evaluate the performance capacities of a small field of view single crystal digital gamma camera for 99Tcm and 191Irm at high count rates. The camera dead time for 99Tcm (window 30%) was well corrected up to 300 kcps in fast acquisition mode using the relative decrease of a small shielded reference source. Using the decaying activity method for 191Irm the non-linearity response of the gamma camera was corrected by an 191Os reference soruce up to 210 kcps at 70 keV, 75 kcps at 129 keV and 320 kcps including both peaks. Saturation count rates were respectively 270 kcps, 150 kcps and 420 kcps and high count rate resolution (FWHM) 9.0, 7.3 and 10.3 mm. Since the accuracy of first pass measurements is more sensitive to count rate than to spatial resolution the 50-150 keV window was chosen for clinical studies. In data obtained from 32 ECG gated FPRNA patient studies, the whole field of view count rate during the left ventricular phase ranged from 100 to 250 kcps with 80 to 120 mCi (2960-4400 MBq) of 191Irm and 100 to 180 kcps with 20 to 25 mCi (750-925 MBq) of 99Tcm red blood cells permitting for both tracers accurate non-linearity correction.

Bone marrow content measured in radioimmune bone marrow scintigraphy: intra- and inter-observer variability.

The aim of this study was to assess the possible quantification of vertebral residual bone marrow content relative to the bone marrow content of a non-irradiated vertebra. This method is based on the vertebral count activity, measured using radioimmune bone marrow scintigraphy. First, however, we had to evaluate intra- and inter-observer variability. In three patients who underwent radioimmune bone marrow scintigraphy, two independent observers measured the count density in 51 (15 lumbar and 36 thoracic) vertebrae using a manually drawn region of interest. To evaluate intra- and inter-observer variability, we calculated the means and standard deviations of the differences between measurements. Bland-Altman plots were drawn for all vertebrae as well as for three subgroups of vertebrae (the upper thoracic spine, D1-D6; the lower thoracic spine, D7-D12; and the lumber spine, L1-L5). For all vertebrae, the mean (+/- S.D.) difference, expressed as a percentage of the overall mean, was -0.44 +/- 3.3% for observer 1 and -0.3 +/- 2.1% for observer 2 for intra-observer variability; inter-observer variability varied from 0.55 +/- 3.9% to 1.28 +/- 3.7%. On the Bland-Altman plots, the data points were evenly distributed above and below the 0-line and the linear regression equations matched the line of equality almost perfectly. This pattern was observed for all the vertebrae as well as for the subgroups of vertebrae. In conclusion, our results show that the intra- and inter-observer variabilities are not great, confirming that this technique is simple and robust and can be used for further quantification of bone marrow content in the axial skeleton.

Primary cerebral lymphoma visualised by means of In-111-pentetreotide scintigraphy.

Primary lymphoma of the central nervous system, until recently representing about 1% of all brain tumours, shows a dramatically increased incidence in the general population as well as in high-risk groups (immunocompromised, AIDS), and may rise up to 6% in a population of AIDS patients. The clinical presentation is variable and cannot reliably be distinguished from other intracerebral tumours. At present, CT and MRI are the methods of choice for diagnosing cerebral lymphomas. However, their characteristics are not specific. The radiological picture may suggest glioma, meningioma, metastatic carcinoma or even a cerebrovascular accident. A labelled somatostatin analogue (pentetreotide) has been proposed as a new tracer for the imaging of somatostatin receptors, which have been identified by immunocytochemical or radioimmunoassay techniques in several organ systems. Somatostatin receptors were also identified in surgical biopsy samples from patients with Hodgkin and non-Hodgkin lymphoma and extracerebral lymphoma has already been visualised in vivo by means of In-111-labelled pentetreotide. While CT images of the brain showed a regression of the tumour after radiotherapeutic treatment, the scintigraphic images showed persistence of the tumoural tissue, corresponding with the clinical evolution and outcome. Furthermore, the absence of extra-cerebral lymphoma tissue, seen on the whole body images, was confirmed by post-mortem examination. To our knowledge, this is the first report of a primary intracerebral lymphoma visualised by means In-111-pentetreotide.

Hemodynamic effects of nebivolol in men: comparison of radionuclide angiocardiography with systolic time intervals.

In a subacute experiment the authors studied the effects of a fourteen -day treatment with nebivolol, 5 mg once a day, in 10 healthy male volunteers with a mean age of thirty-one, twenty-five to thirty-nine years, by comparing the results of the resting ratio of the preejection period (PEP) to the left ventricular ejection time (LVET), as measured by systolic time intervals (STI), with the results obtained by equilibrium radionuclide angiocardiography (ERNA), using technetium 99m-labeled autologous red blood cells as a marker. A submaximal treadmill exercise test performed before and during treatment demonstrated that nebivolol significantly (p less than 0.01) reduced peak exercise heart rate and systolic blood pressure from a mean value of 158 +/- 5.4 bpm to 131 +/- 4.3 bpm and from 171 +/- 4.9 mmHg to 144 +/- 4.5 mmHg respectively. The data from the STI and ERNA were calculated and analyzed independently by two observers. A highly significant (r = 0.8182, p = 0.0038) correlation was found between the changes of stroke volume (SV) and PEPc/LVETc during treatment with nebivolol. Furthermore end-diastolic volume significantly(p = 0.03) increased from a mean value of 177 +/- 10.1 ml to 198 +/- 6 ml and stroke volume significantly (p = 0.01) increased from 120 +/- 6.8 ml to 136 +/- 6.3 ml. Systemic vascular resistance tended to decrease from a mean value of 11.4 +/- 1.28 units to 10.6 +/- 1.10 units. No changes could be observed either in ejection fraction or in cardiac output.(ABSTRACT TRUNCATED AT 250 WORDS)

Workflow in nuclear medicine.

This paper discusses a workflow management system for nuclear medicine. It augments the more conventional PACS with automatic transfer of studies along the chain of activities making up an examination in nuclear medicine. A prototype system has been designed, built, and installed in a department of nuclear medicine, active in a network of hospitals.

Nuclear cardiology, Part II: Scintigraphic evaluation of cardiac function.

OBJECTIVE: Different methods are currently available to assess cardiac function, especially left ventricular ejection fraction, using either planar or tomographic imaging, first-pass or equilibrium techniques, and blood-pool or myocardial perfusion agents. This is the second article of a four-part series on nuclear cardiology. In this article the authors review the most widely used radiopharmaceuticals and methodologies.

Repeat thallium-201 SPECT in cerebral lymphoma.

The authors report on the contribution of Thallium-201 brain SPECT in the diagnosis and follow-up of a non-immunosuppressed patient, presenting with primary cerebral lymphoma. The tumoral process was at first not diagnosed on CT-scan, but Thallium-201 SPECT suggested a tumoral invasion. During corticosteroid treatment the tumor volume on CT-scan decreased, while on Thallium-201 SPECT there was an enhancement of the accumulation and an increasing tumor to non-tumor ratio. These scintigraphical findings more closely reflected the clinical course and the postmortem results.

Visualization of brainstem perfusion using a high spatial resolution SPECT system.

The authors explored the high spatial resolution of a three-head rotating SPECT system, equipped with lead super-fine fanbeam collimator. The brainstem was high-lighted in a three-dimensional reconstruction, showing perfusion small structures such as mesencephalon, pons, and medulla oblongata. The visualization of brainstem perfusion sets new landmarks in functional neuroimaging and, moreover, was obtained with a commercially available three-head SPECT system.

A porcelain gallbladder affecting the assessment of bone mineral content.

Dual-photon absorptiometry is a reliable method for the assessment of bone mineral content (BMC). The presence of focal bone disease, degenerative joint disease, or aortic calcifications may complicate the evaluation of BMC and may lead to erroneous findings. The misleading effect of a porcelain gallbladder is described.

Continuous anterior acquisitions in gastric emptying: comparison with the mean.

Depth correction is necessary when gastric emptying is studied by means of a labeled meal. In this study continuous anterior images were acquired from the onset of the food ingestion. Differences in depth were measured using a left lateral view. A minimal and crude depth correction was performed. The results obtained with this correction method were compared with those obtained using the depth correction technique of the mean. The results obtained in the anterior projection without any depth correction were also compared with those obtained using the method of the mean. The results obtained with both correction techniques were identical in 18 gastric emptying studies. This approach also permits the creation of a time-activity curve over the duodenum in the anterior projection. In this way the lag phase can easily be assessed.

Diagnostic value of Tc-99m sestamibi gated SPECT to assess viability in a patient after acute myocardial infarction.

The case of a 56-year-old woman who was admitted with an acute anteroseptal myocardial infarction showed severely decreased left ventricular function and regional wall motion abnormalities on planar Tc-99m gated blood pool imaging. Tc-99m sestamibi stress SPECT imaging demonstrated residual peri-infarct ischemia. At angiography, a solitary severe proximal left anterior descending stenosis was successfully dilated. Later, because of recurrent chest pain, a second Tc-99m sestamibi stress-rest SPECT was performed to exclude restenosis. Because the question of viability within the infarct region had also been asked, a gated protocol was applied and compared to TI-201 rest-redistribution SPECT. Both tests pointed to the existence of tissue viability in the septal region, without evidence for stress ischemia. The patient was then medically treated. One year later, because of angina, Tc-99m gated SPECT blood pool imaging showed a spectacular increase in left ventricular function and a dramatic improvement in regional wall motion. Angiographic data confirmed these findings and there was no significant restenosis. Thus, Tc-99m sestamibi gated SPECT may be helpful in predicting viability and recovery of function in patients with severely impaired left ventricular regional wall motion after acute myocardial infarction.

Radionuclide venography using continuous Kr-18 m infusion: preliminary note.

Continuous infusion of Kr-81m presents important advantages compared to the commonly used radionuclides for venography. High count rates can be accumulated, and a high resolution collimator can be employed to ensure good quality images. The study can be repeated immediately and multiple views can be performed until a satisfactory result is obtained. The production of radionuclide from a Rb-81--Kr-81m generator suitable for intravenous infusion is almost the same as that which is suitable for ventilation. The same generator can first be used for venography and then for ventilation imaging to complete the work-up patients suspected of having thromboembolic disease.