Gunaydin Erbengi

Regional cerebral blood flow changes in chronic alcoholism using Tc-99m HMPAO SPECT. Comparison with CT parameters.

Twenty-eight patients were studied for regional cerebral blood flow changes as a result of chronic alcoholism. After the administration of 550 to 600 MBq Tc-99m HMPAO, tomographic slices were obtained using a SPECT camera. Eight regions per hemisphere were drawn on each transaxial section, and tracer redistribution was calculated for each region. Region-to-whole slice ratios were determined for each patient. Patients had significantly decreased frontal/whole slice (1 ± 0.02) ratios in comparison with a normal group (p< 0.01). Twenty-four out of 26 patients (85.7%) demonstrated abnormal rCBF. Eighteen out of 28 (64.3%) showed activity lower in the left hemisphere than in the right. Using CT parameters, 60% of the patients had either sulcal widening and/or ventricular enlargement. The frontal region and the left hemisphere were more affected by alcohol than other regions. More cerebral blood flow changes than morphologic changes were found caused by alcoholism.

Tc-99m HMPAO/SPECT determination of regional cerebral blood flow changes in schizophrenics.

Hypofrontality (hypometabolism and hypoperfusion) has been demonstrated in patients with schizophrenia by the use of several imaging methods, such as positron emission tomography (PET). In this study, Tc-99m hexamethylpropylene amineoxime (HMPAO) and SPECT were used to investigate regional blood flow changes in 20 schizophrenic patients (12 males and 8 females, aged 15—50 years) experiencing acoustic hallucinations. Tc-99m HMPAO (15-20 mCi) was injected intravenously, eight regions/hemisphere were drawn on transaxial sections, and tracer redistribution was calculated for each region. Frontal/occipital ratios (0.917 ± 0.045) and frontal/wholeslice ratios (0.984 ± 0.036) were determined for each patient. The patients had significantly lower frontal/occipital ratios (P < 0.0005) and lower frontal/wholeslice ratios (P < 0.01) in comparison to a normal group (11 cases).

Increased accumulation of Tc-99m MIBI in undifferentiated mesenchymal tumor and its metastatic lung lesions

The authors report a case of undifferentiated mesenchymal tumor in which a Tc-99m MIBI scan demonstrated increased accumulation in the primary site but not in the necrotic areas. Metastatic lung lesions of the tumor were also clearly demonstrated. Thus, they conclude that Tc-99m MIBI can be used to detect and locate a mesenchymal tumor and to assess its viability.

Scintigraphic evaluation of healing response after heterograft usage for alveolar extraction cavity

OBJECTIVE Reconstruction of bone defects remains an important problem in oral and maxillofacial surgery. Restoration of defect sites with various grafting materials is a valuable approach to the solution of this problem. The aim of this study was to evaluate the effects of the use of heterografts on osteoblastic activity by means of a radionuclide technique. STUDY DESIGN The postextraction alveolar cavities of impacted mandibular third molars on 22 patients were used as a healing model for this study. Granulated freeze-dried heterograft material of bovine origin was used on 11 patients; the other 11 patients constituted a control group. On each patient, three-phase bone scans were performed on postoperative days 7 and 28. RESULTS Although dynamic and blood pool studies showed similar patterns with respect to the mean values of asymmetry ratios of operation sites to the contralateral sides for the 7th- and 28th-day scans, static-phase bone scans revealed that healing response through osteoinduction was more prominent in the study group than in the control group. A significant increase in the mean value of the ratio from the first scan to the second was observed on static images in the study group (first scan, 1.6 +/- 0.2; second scan, 2.0 +/- 0.5; p < 0.05). However, the same ratio failed to show any significant change in the control group (first scan, 1.5 +/- 0.2; second scan, 1.5 +/- 0.3; p > 0.05). CONCLUSION Static-phase bone scintigraphy showed that when freeze-dried heterograft material is used to fill alveolar extraction cavities, it stimulates osteoblastic activity, which in turn leads to acceleration of the healing process and helps to maintain the linearity of bony structure. Moreover, radionuclide study can be used to evaluate the viability of freeze-dried heterografts in the 4th postoperative week, at which time no additional increase in perfusion resulting from surgical trauma was found in our series.

Brain death: determination with brain stem evoked potentials and radionuclide isotope studies.

SummaryThirty-three patients fulfilling the clinical criteria for brain death were tested by Brainstem Auditory Evoked Potentials (BAEP) and Radionuclide Cerebral Angiography and Brain Perfusion Studies. There was a significant correlation between the BAEP and radionuclide study outcomes. All patients with absence of BAEP showed no cerebral perfusion. These findings, added to the clinical findings, resulted in a final diagnosis of brain death in all patients. It is concluded that BAEP and Radionuclide Cerebral Perfusion studies are useful adjuncts for proving that brain death has really occurred.

Tl-201 uptake in brown tumors of hyperparathyroidism.

TI-201 chloride bone scans were performed on nine patients with primary hyperparathyroidism just after TI-201 and Tc-99m parathyroid subtraction scintigraphy. Bone lesions accumulate TI-201, especially in sites of brown tumor formation. This was proven by the histopathologic examination of two patients. Eight patients had bone scans with Tc-99m MDP. The lesion-to-background ratio was quantified in seven patients for TI-201 and in four patients for Tc-99m MDP. TI-201 uptake of the lesions were quantified in two patients. The lesion-to-background ratio was 1.63 ± 0.21 and 2.51 ± 0.88 for TI-201 and Tc-99m MDP, respectively. A Ga-67 citrate scan was performed on one patient, and the lesion-to-background ratio was 1.49 ± 0.06. The accumulation of TI-201 in brown tumors of bone might be due to increased blood flow and local metabolic activity. TI-201 chloride was inferior to Tc-99m MDP in lesion detection. It is concluded that bone imaging with TI-201 can easily be performed following parathyroid subtraction scintigraphy to delineate the sites of brown tumor formation.

Scintigraphic Evaluation of the Short- and Long-Term Renal Effects of Oral Felodipine Using Technetium-99m-Mercaptoacetyl Triglycine

The short- and long-term effect of felodipine on renal perfusion and tubular function was investigated using a new renal tubular imaging agent, 99mTc-mercaptoacetyl triglycine (99mTc-MAG3). Twelve patients with essential hypertension (mean age = 49 +/- 8 years) were studied. Renal scintigraphies with 180 MBq 99mTc-MAG3 were performed at baseline, at the 2nd hour following oral administration of 5 mg felodipine and 4 weeks later on 5-10 mg daily felodipine therapy. The time-activity curves of each kidney were obtained following background subtraction. The 99mTc-MAG3 clearance value was measured for each kidney. In addition, perfusion index (PI), reno index, time to maximum, half-maximum and two thirds of maximum activity values of each kidney were calculated. Systolic and diastolic blood pressures were significantly lowered with long-term administration of felodipine (from 159 +/- 12/105 +/- 5 to 141 +/- 11/87 +/- 7 mm Hg, p = 0.01 and p = 0.002, respectively). Heart rate did not change significantly. Initially, a decrease in PI indicating an increase in renal blood flow (from 246 +/- 96 to 194 +/- 54, p = 0.01) was observed, whereas no change was noted during the chronic administration (to 230 +/- 69, p = NS). Total clearance of 99mTc-MAG3 was decreased nonsignificantly following the initial dose of felodipine (from 361 +/- 93 to 351 +/- 91 ml/min, p = NS). During long-term therapy, felodipine did not alter the perfusion and tubular function of the kidneys. Our results indicated that felodipine causes a significant increase in renal blood flow initially, even with a nonsignificant change in systemic blood pressure.

Scintigraphic evaluation of reduced-size liver transplant from living related donor in Byler's disease

Bylers syndrome is a rare form of autosomal recessive intrahepatic cholestasis that is fatal in children. A 10-year-old girl diagnosed with Bylers syndrome underwent reduced-size liver transplantation using lateral segments of her living mothers liver. The donors and the recipients liver functions after transplantation were evaluated using Tc-99m disofenin and Tc-99m SC to investigate morphology, liver perfusion, and hepatobiliary function.

SCINTIGRAPHIC EVALUATION OF RENAL FUNCTION IN HEART-BEATING BRAIN DEATH PATIENTS USING TECHNETIUM-99M DIETHYLENETRIAMINE PENTAACETIC ACID

Assoc. Prof. Belkis Erbas, MD, Klinikum rechts der Isar der TUM, Nuklearmedizinische Klinik, Ismaninger Strasse 22, D-W8000 München 80 (FRG) Dear Sir, There is a need to define brain death as soon as it occurs, in order to be able to salvage organs for possible transplantation. The ra-dionuclide and radiographic procedures infer brain death on the basis of demonstrated cessation of cerebral blood now [1]. However, radiographic studies cannot be performed at the bedside, are more costly and involve administration of contrast material, with its attendant risks for the patient, an in the case of potential renal transplant donors, for the viability of the transplanted kidney. Radionuclide techniques provide a non-invasive and reliable method for the diagnosis of brain death with no risk for the patients [2, 3]. Radionuclide cerebral angiography, one of the tests used to confirm brain death, can demonstrate the absence of cerebral blood flow during the firstpass study [4]. Several technetium (Tc) compounds, such as 99mTc pertnechnetate, 99mTc diethylenetriamine pentaacetic acid (DTPA) and 99mTc gluco-heptonate, can be used for this purpose. 99mTc-DTPA, used for both cerebral angiography and static brain scintigraphy, has an advantage over the other radionuclide compounds because of its ability to demostrate renal perfusion and glomerular filtration functions at the same time. During the scintigraphic evaluation of cerebral blood flow, we investigated the renal function of 19 patients with brain death confirmed using the clinical findings and brain-stem-evoked auditory potential. Following intravenous administration of 370 mBq (10 mCi) 99mTc-DTPA, cerebral angiography was performed in the first 2 min. Immediately, a gamma camera was placed under the patient to image the renal regions. Renal uptake of 99mTcDTPA was recorded in a matrix size of 256 × 256 with a total count of 500.000 per image during 20 min with 5-min intervals. The symmetry and homogenity of renal accumulation of radiotracer, visualization time of the renal pelvis, patency of the ureters and bladder were examined. Following renal imaging, anterior, posterior and lateral views of the head were recorded in order to complete the brain scan. Fifteen patients had a good function of both kidneys. Three patients showed a significant decrease in renal function bilaterally, and 1 patient had a single kidney. The kidneys of 3 patients with normal renal function who fulfilled the other criteria for renal transplantation were used for

Tc-99m HMPAO labeled donor leukocyte scan in liver transplant.

Tc-99m HMPAO labeled donor leukocytes were used to image the focus of an hepatic infection in a 32-year-old liver transplant patient. Six hours after the administration of labeled leukocytes, radioactivity accumulation was detected in the liver suggesting an intrahepatic infection focus. Diagnosis of infection was confirmed at surgery.