Coskun F. Bekdik

Assessment of changes in regional cerebral blood flow in patients with major depression using the 99mTc-HMPAO single photon emission tomography method

Regional cerebral blood flow was investigated in 14 patients with major depression diagnosed according to the DSM-III-R criteria (six patients with single and eight patients with recurrent episodes) and in ten healthy volunteers. The mean ages of the patients and the controls were 33.5 ± 2.7 and 31.6 ± 2.6 years, respectively. The severity of the depression was assessed using the 17-item Hamilton Depression Scale (mean: 23.2 ± 1.5). None of the patients was under medication. After administration of 500 MBq technetium-99m hexamethylpropylene amine oxime, a single photon emission tomography study was performed and then transaxial, sagittal and coronal slices were obtained. For the semiquantitative analysis of the data, the ratios of the mean counts/pixel to the whole slice were calculated for 24 regions on three consecutive transaxial slices in the orbitomeatal plane. Additionally, left/right and frontal/occipital ratios were calculated. Both sides of the temporal region had a significantly decreased cerebral blood flow (CBF) when compared to the controls. The left/right ratio of the prefrontal region was also significantly lower in the patients than in the controls. The Hamilton score had a negative correlation with blood flow in the anterofrontal and left prefrontal regions. According to our results, regional CBF seems to be decreased in the left prefrontal and in both temporal regions in major depression. The severity of depression is correlated with the reduction in CBF in the regions of the anterofrontal and left prefrontal cortex.

Comparison of 99mTc(V)-DMSA, 201Tl and 99mTc-MIBI imaging in the follow-up of patients with medullary carcinoma of the thyroid

Radionuclide scanning with tumour-seeking agents such as pentavalent technetium-99m dimercaptosuccinic acid [99mTc(V)-DMSA], thallium-201 and technetium-99m sestamibi (MIBI) has been reported to be useful in the detection of medullary thyroid carcinoma (MTC). We undertook a study in 14 MTC patients to determine the comparative imaging potential of201Tl, MIBI and99mTc(V)-DMSA in the detection of recurrent or metastatic MTC. All patients underwent total thyroidectomy and had persistently elevated serum calcitonin levels after the surgery. Scintigraphic studies were carried out 20 min after the injection of 111 MBq of201Tl or 555 MBq of MIBI and 2 h following the injection of 370 MBq of99mTc(V)-DMSA. All scintigraphic findings were correlated with contemporaneous CT or MRI studies. CT, MRI and bone scans showed 42 (26 bone, 16 soft tissue) metastatic sites in 11 of the 14 patients. In the remaining three patients no lesions were detected during diagnostic evaluation.99mTc(V)-DMSA showed all of the soft tissue metastases but could not show two bone lesions. On the other hand, MIBI imaging was false-negative in 22 (52%) sites and201Tl was false-negative in 34 (80%) sites. Overall, lesion detection sensitivities for99mTc(V)-DMSA, MIBI and201Tl were 95%, 47% and 19% respectively. We conclude that99mTc(V)-DMSA is clearly superior to MIBI and201Tl in the follow-up of MTC patients.

Preoperative localization of parathyroid carcinoma using Tc-99m MIBI

A patient with parathyroid cancer is presented who underwent Tc-99m MIBI scintigraphy. The Tc-99m MIBI image demonstrated increased accumulation of activity at the lower pole of the left thyroid lobe which was later confirmed as a parathyroid cancer. Uptake by parathyroid cancer must be kept in mind as a cause of increased Tc-99m MIBI accumulation when a disease is in question in the thyroid or parathyroid gland.

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.

Bleomycin lung toxicity detected by technetium-99m diethylene triamine penta-acetic acid aerosol scintigraphy

In this study we investigated bleomycin-induced pulmonary toxicity in patients with germ-cell tumour by means of technetium-99m diethylene triamine penta-acetic acid aerosol scintigraphy. Twenty untreated patients who had no clinical or radiological evidence of pulmonary disease received four courses of etoposide, cisplatin and bleomycin chemotherapy. Aerosol lung scintigraphy and pulmonary function tests were performed in all patients before bleomycin treatment and after administration of 180 and 360 mg bleomycin. On the basis of the scintigrams the percentage decline in activity per minute (Kep) was evaluated, which represented an accurate parameter of lung membrane permeability. Pretreatment Kep values (0.891 ±0.286) were significantly lower than those obtained following 180 and 360 mg bleomycin treatment (1.176±0.336 and 1.389±0.477, respectively; P<0.0005). The Kep values obtained with 180 and 360 mg bleomycin treatments were also significantly different (P<0.005). In contrast, no significant change was observed in the results of pulmonary function tests. Our results demonstrate that evaluation of the pulmonary clearance of 99mTc-DTPA represents a useful means of monitoring the functional status of the lung epithelial membrane during bleomycin treatment. Further prospective studies are needed to assess the relationship between increase in permeability and development of lung toxicity in order to decide which patients should discontinue bleomycin therapy.

Measurement of pancreatic blood flow in dog by133Xe clearance technique

SummaryThe water/gas, plasma/gas, erythrocyte/gas and pancreas/gas partition coefficients of133Xe were measured at 37° C using dog tissues. The pancreas/blood partition coefficients were calculated from these figures and plotted as a function of hematocrit. The133Xe pancreas/blood partition coefficient in the normal range was 1.2 ml/g.Pancreatic blood flow was determined in each case by injecting the tracer into the pancreaticoduodenal artery (mean 106.8±30.4 ml/100 g/min). Pancreatic blood flows were also determined by injecting the tracer into the tissue of head, body and the tail of pancreas. The means of the results were 62.4±22.2, 85.7±35.6 and 67.1±26.4 ml/100 g/min respectively. The mean pancreatic blood flow obtained by intra-arterial injection was significantly different (P<0.05) from the results obtained by injecting133Xe into the head or tail, but was not statistically different from that of the body of pancreas. The results of the head, body and tail of pancreas were not significantly different from each other (P>0.05).

Scintigraphic evaluation of left ventricular function and correlation with autonomic cardiac neuropathy in diabetic patients

Left ventricular function of 20 diabetic patients was investigated at rest and during hand-grip test using radionuclide ventriculography. The aim of the study was to discuss the correlation of cardiac function with autonomic cardiac neuropathy (ACN) in diabetic subjects. ACN was tested using heart rate response to valsalva maneuver, standing up, deep breathing; blood pressure response to standing up, sustained hand-grip, and additionally corrected QT (QTc) measurements. Plasma glucose regulation was screened with fructosamine levels. Ejection fraction (EF), peak ejection (PER) and filling rates (PFR), times to peak ejection (TPE) and filling (TPF), time to endsystole (TES), TES/T, TPE/T, TPF/T, 1/3 PER, 1/3 PFR, 1/3 EF, 1/3 FF (filling fraction) we calculated. Thirteen patients had ACN. Six patients (30%) had a low EF at rest. As a response to hand-grip, 14 patients (70%) showed a decrease in EF (9 ACN). PFR was low in 10 patients (50%) at rest and in 12 (60%) during hand-grip. The mean rest PER value of ACN+ patients (4.4 +/- 1.3) was significantly higher than that of controls (2.9 +/- 0.5) and patients without ACN (3.4 +/- 0.4; p < 0.05) as well as the mean 1/3 PER value (1.7 +/- 0.5 vs. 1.3 +/- 0.5; p < 0.05). Fourteen patients (70%) had a fall in PER 10 ACN) as a response to hand-grip. The mean TES/T value of patients with ACN (0.44 +/- 0.05) was significantly higher than of those without ACN (0.38 +/- 0.05; p < 0.05). In conclusion, diastolic dysfunction was detected frequently at rest. Systolic parameters were markedly impaired as a response to hand-grip in patients with ACN. Sympathetic overactivity was noted in ACN+ group at rest. Our results indicated that the patients with diabetes and ACN have subclinical left ventricular diastolic dysfunction and symphatic overactivity.

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.