Accuracy of FDG-PET/CT and paraneoplastic antibodies in diagnosing cancer in paraneoplastic neurological syndromes.

OBJECTIVE: There is still no consensus about whether to perform PET/CT to detect carcinoma in paraneoplastic neurological syndromes (PNS) in patients with or without antibodies. The aim of this study is to determine the diagnostic accuracy of PET/CT and antibodies in patients with PNS. MATERIAL AND METHODS: A retrospective study was conducted on patients with clinically suspected PNS between 2008 and 2013. The association between histopathological findings, paraneoplastic antibodies, and PET/CT findings were evaluated. Sensitivity and specificity for the detection of underlying malignancy were calculated for PET/CT and paraneoplastic antibodies. RESULTS: A total of 42 patients were analyzed. Of these 42 patients, 32 (75%) had a classical PNS, 6 (14%) had positive PET/CT findings, and 34 were tested for the presence of antibodies (anti-Hu Ab, anti-Yo Ab, and anti-Ri Ab). Twenty one of 34 patients had positive antibodies. Of the 6 patients with positive PET/CT findings, 6 had positive histopathological results. Among 21 patients with positive biomarkers, carcinoma was confirmed only in 5 patients. One patient with negative antibodies, but positive PET/CT findings, was diagnosed with a tumor. Gastric carcinoma was detected in 1 patient with negative PET/CT findings and antibodies during follow-up. Based on the results, PET/CT was found to have 85.71% sensitivity, 100% specificity, 100% positive and 97.22% negative predictive values in the detection of tumors. CONCLUSION: PET/CT has a certain diagnostic accuracy for detecting underlying malignancy in patients with PNS, regardless of the presence of paraneoplastic antibodies.

Muscle perfusion with technetium-MIBI in lower extremity peripheral arterial diseases.

There have been several methods utilized in the diagnosis or assessment of medical or surgical treatments of peripheral arterial diseases. In this study, the diagnostic value of a new tracer: 99mTc-methoxy-isobutyl-isonitrile (MIBI) has been demonstrated in patients with leg claudication. We successively performed muscle perfusion scans in 6 normals and 18 patients with claudication pain during rest and after exercise on the same day. Muscle perfusion abnormalities in all patients were consistent with the defects in the arteries of the affected limbs. The results show that this is a simple and accurate diagnostic procedure and superior to those that have been previously used.

Unexpected bone marrow uptake of thallium-201 in nonsecretory myeloma.

A 43-yr-old man was referred for any possible parathyroid abnormality that could explain his hypercalcemia and slightly increased parathormone levels. The thallium-technetium scan showed a diffuse abnormal thallium uptake incidentally in the bone marrow, otherwise parathyroid scan appearance was normal. He had an essentially normal bone scan, although subsequent nanocolloid scintigraphy demonstrated bone marrow expansion. Further investigations, including a bone marrow aspiration biopsy, confirmed the diagnosis of nonsecretory myeloma. This finding suggests that 201Tl imaging can be a useful tool to investigate those patients suffering from similar myeloid disorders causing bone marrow hyperplasia.

Technetium-99m-N,N-ethylenedicysteine--a comparative study of renal scintigraphy with technetium-99m-MAG3 and iodine-131-OIH in patients with obstructive renal disease.

UNLABELLED: Technetium-99m-labeled N,N-ethylenedicysteine (99mTc-EC) is a new renal imaging agent introduced as an alternative for 99mTc-labeled mercaptoacetyltriglycine (99mTc-MAG3), with similar renal excretion characteristics. To evaluate the diagnostic characteristics of this agent, a gamma camera study was performed. METHODS: Sixteen patients with obstructive renal disease and six normal controls were injected with 90 to 110 MBq of 99mTc-EC and 7.4 MBq 131I-labeled orthoiodohippurate (OIH). Serial images were obtained during 20 min for 99mTc-EC and 30 min for OIH. The study was repeated using 90 to 110 MBq 99mTc-MAG3 during the same week. RESULTS: Renograms, functional ratios and urinary excretion patterns of all three agents were similar. The mean time to peak activity values for OIH, 99mTc-EC and 99mTc-MAG3 were 4.25 +/- 0.37 min, 4.39 +/- 0.32 min and 4.00 +/- 0.24 min, respectively. The time from peak to 50% activity values for OIH, 99mTc-EC and 99mTc-MAG3 were 5.48 +/- 0.80 min, 6.93 +/- 0.69 min and 7.33 +/- 0.85 min, respectively. CONCLUSION: It is concluded that 99mTc-EC has excellent imaging characteristics and similar excretion properties to OIH. The advantages of 99mTc-EC over 99mTc-MAG3 are lower hepatobiliary uptake and simplicity of preparation.

Technetium-99m-MIBI scintigraphy in pulmonary tuberculosis.

UNLABELLED: We investigated the usefulness of 99mTc-methoxyisobutylisonitrile scintigraphy in patients with known or suspected pulmonary tuberculosis (PTB) in comparison with radiological and bacteriological findings. METHODS: Thirty-six patients aged 13-59 yr were scanned 15 and 60 min after intravenous injection of 370 MBq (10 mCi) 99mTc-methoxyisobutylisonitrile. Twenty-four patients had active PTB proven by chest radiograph and sputum examinations, two had miliary tuberculosis and ten were suspected of having relapsed PTB with negative sputum examinations and indeterminate chest radiographs. In 12 patients 99mTc-MIBI imaging was repeated 1-3 mo after chemotherapy. RESULTS: Of 24 patients with active localized PTB, 22 (92%) showed increased focal uptake of 99mTc-MIBI, but two patients with minimal infiltration on chest radiographs had no accumulation of 99mTc-MIBI. Both patients with miliary PTB showed diffuse 99mTc-MIBI uptake in the lungs. Among 10 patients with suspicion of relapse, 99mTc-MIBI scans were true-positive in 4 of 5 patients (80%) with culture-proven tuberculosis and false-positive in 2 of 5 (40%) patients with negative sputum cultures. For repeat imaging, 6 of 10 patients with active localized PTB showed reduced MIBI uptake, which correlated with chest radiograph findings, and one patient had increased MIBI uptake again concordant with clinical and radiological findings which were suggestive of resistance to first line chemotherapy of tuberculosis. The other three patients showed no significant scintigraphic changes despite clinical and partial radiological regression. CONCLUSION: Active PTB granulomas generally present considerable 99mTc-MIBI uptake that is most probably related to disease activity. Therefore, 99mTc-MIBI scanning could be used in the detection and follow-up of active PTB as a complement to routine techniques.

Comparison of 99mTc-methoxyisobutyl isonitrile and 201T1 scintigraphy in visualization of suppressed thyroid tissue.

UNLABELLED: Both (201)TI and (99m)Tc-methoxyisobutyl isonitrile (MIBI) have been used in the visualization of suppressed thyroid tissue in patients with autonomously functioning thyroid nodules (AFTNs). It has been suggested that thyroid-stimulating hormone (TSH) control is not a major determinant of both tracers. However, the mechanism of thyroid uptake of these agents is controversial. In this study, we compared (201)TI and MIBI in the visualization of suppressed thyroid tissue in patients with a solitary toxic AFTN. METHODS: Thirty-two patients (13 triiodothyronine [T3] and 19 T3 + levorotatory thyroxine [T4] hyperthyroid patients) with toxic AFTNs visualized on (99m)Tc-pertechnetate scanning were included in the study. All patients underwent MIBI and (201)TI thyroid scintigraphy within a 3-d interval. The scintigrams were analyzed both visually and semiquantitatively. For the semiquantitative analysis, regions of interest (ROIs) were generated over the nodule (N) and contralateral normal lobe (E), and the mean counts in each ROI were calculated. RESULTS: The N/E uptakes (mean +/- SD) for pertechnetate, MIBI, and (201)TI were 11.37 +/- 4.53, 4.76 +/- 1.38, and 1.63 +/- 0.15, respectively, in T3 + T4 hyperthyroid patients and 9.46 +/- 3.64, 2.73 +/- 0.63, and 1.57 +/- 0.23, respectively, in T3 hyperthyroid patients. Our results showed that (201)TI uptake of suppressed thyroid tissue compared with AFTN was more prominent and significantly higher than that of MIBI for both groups of patients (P = 1.08E-05 for T3 and 6.15E-09 for T3 + T4 hyperthyroidism). There was no significant difference for either pertechnetate or (201)TI (P > 0.05) when the N/E uptakes of both groups of patients were compared. However, the N/E uptake of MIBI in T3 + T4 hyperthyroid patients was significantly higher than that in T3 hyperthyroid patients (P = 6.69E-06). CONCLUSION: Clear visualization of suppressed thyroid tissue with both (201)TI and MIBI in patients with low serum concentrations of TSH suggests that TSH is not a major factor in the thyroid uptake of either agent. (201)TI is superior to MIBI in the visualization of suppressed thyroid tissue in patients with a toxic thyroid nodule. An increased rate of metabolism in the follicular cells of AFTNs in T3 + T4 hyperthyroid patients compared with that in T3 hyperthyroid patients might be responsible for the higher N/E for MIBI compared with that for (201)TI.

Prospective validation of single plasma sample 99mTc-ethylenedicysteine clearance in adults.

UNLABELLED: 99mTc-L,L-ethylene, L, dicysteine (EC) clearance shows strong correlation with orthoiodohippurate clearance, and it is possible to estimate effective renal plasma flow from 99mTc-EC clearance. In routine clinical studies, it is practical to use the one or two plasma sample method instead of multiple plasma samples for clearance determination. A single-sample technique was developed for 99mTc-EC, and a regression formula was generated. A prospective study tested the validity of this regression formula. METHODS: The study population was composed of 26 patients with a wide range of renal function. Multiple plasma sample 99mTc-EC clearances were calculated from all patients using the open two-compartment model. Single plasma sample clearances were also determined from the 54-min plasma sample using the regression formula published previously. RESULTS: The multiple-sample plasma clearance of 99mTc-EC ranged from 46 to 668 mL/min with a mean of 300.76 +/- 150.73 mL/min. The clearances obtained from the 54-min plasma sample ranged from 49 to 699 mL/min, with a mean of 297.39 +/- 152.23 mL/min. There was an excellent correlation between the clearances obtained by the two techniques (r = 0.99, slope = 0.9911). The standard error of estimation was found to be 25.9 mL/min. CONCLUSION: This study suggests that 99mTc-EC clearance can be estimated from 54-min plasma samples with an acceptable error of estimation for most routine clinical studies.

A method to evaluate microcirculatory vascular patency of full thickness burn in an animal model.

BACKGROUND: In cases of thermal injuries it is always difficult to predict the extent of necrosis to the peripheral ischemic zone. Practically, full-thickness skin burn also affects the underlying muscle, panniculus carnosus, which adheres tightly to the skin. In this proposed model, the muscle which was always partly damaged also covers the ischemic zone of full-thickness burn injury. To evaluate the deeper levels of injury, the status of the micro circulation of thermally affected muscle was evaluated by counting the accumulated radioactive agent, 99mTc methoxyisobutylisonitril (MIBI) in the muscle cells. METHODS: 370 MBq/kg (10 mCi/kg) MIBI was administered intravenously to the animals having burn injuries by a comb device as described in previous literature. Then, 20 minutes after injection, whole burned areas were excised and placed under a gamma camera. Each thermally injured area showed four rectangular defects with lower tracer uptakes than the three adjacent interspaces. The tracer uptake of the burned sites and interspaces was analyzed from the acquired images on a computer, and the degree of injury could be assessed quantitatively. Additionally, specimen counts were obtained from selected burned stripes, interspaces and normal tissue for comparison. RESULTS: Burned sites were evident with lower tracer uptakes whereas interspaces with higher uptakes. Captured activity in interspaces indicated that capillary patency mostly maintained and it permitted the arrival of the radiopharmaceutical to the muscle cells. CONCLUSIONS: Muscle layer, where just below the burn area and tightly attached to the skin, could be assessed as a representative of the extension of the injury.

The role of 99Tcm-tetrofosmin in the evaluation of thyroid nodules.

Various radionuclides, including 67Ga, 201Tl and 99Tcm-sestamibi, have been used to differentiate benign from malignant thyroid nodules. 99Tcm-tetrofosmin, a lipophilic cationic radiotracer, and 99Tcm-sestamibi have also been reported to accumulate in thyroid tumours. In this study, we evaluated the role of 99Tcm-tetrofosmin in the differentiation of malignant from benign thyroid nodules. Seventy-nine patients with solitary non-functioning thyroid nodules were included in the study. Fine-needle aspiration biopsy was performed in all patients. Sixty patients were subsequently operated on and 19 patients refused surgery. After the injection of 370 MBq 99Tcm-tetrofosmin, static images at 5, 30, 60, 120 and 180 min were acquired. Both visual and semi-quantitative analysis was performed. On visual interpretation, the nodules with late retention were classified as positive for malignancy and nodules without late retention were classified as negative for malignancy. In the semi-quantitative analysis, regions of interests were drawn over the nodule and contralateral normal thyroid tissue. The average number of counts was recorded and tumour-to-normal thyroid tissue ratios calculated. Post-operative histology revealed 19 malignant and 41 benign nodules. Of the benign nodules, adenomas behaved similarly to the malignant nodules with late retention of tracer, while adenomatous nodules revealed no late retention on delayed images and could be differentiated from malignant tumours. In the semi-quantitative analysis, there was a significant difference in tumour-to-normal tissue ratios for adenomatous nodules and malignant tumours as well as adenomas. We conclude that it is not possible to differentiate between malignant and benign thyroid nodules with 99Tcm-tetrofosmin. However, 99Tcm-tetrofosmin scintigraphy is helpful in selecting nodules that can be cured by surgical intervention.

Effects of allopurinol, ibuprofen and cyclosporin A on local microcirculatory disturbance due to burn injuries.

This experiment was designed to study the reactions in the surrounding area of burn injury that may lead to further necrosis in 24 h. To prevent extension of burn size into the tissue adjacent to burn injury, it was attempted to reduce progressive microvascular damage by different drugs (ibuprofen, allopurinol or cyclosporin A (CyA)) in a rat model. The burn model consisted of a row of four 10 x 20 mm burn areas separated by three unburned 5 x 20 mm skin bridges (interspaces). To evaluate microcirculation and perfusion of panniculus carnosus muscle which is beneath the burned area of skin, the radioactive agent, technetium-99m methoxyisobutylisonitrile (99Tc01-MIBI) was used 24 h after the burn. Capillary permeability of injured tissue was assessed by the wet and dry weight technique. In all study groups, interspaces showed higher uptakes of 99Tc01-MIBI between 40 and 95 per cent, in comparison with burn sites in the first 24 h following burn. Among the treated rats better results were obtained by allopurinol and CyA treatment that commenced before burn than ibuprofen. Wet and dry ratios were found to be significantly lower in interspaces in rats pretreated with allopurinol and CyA. Results of this experiment showed that neutrophils and free radical-mediated injury may be involved in the pathogenesis of local response to thermal injury, and allopurinol and CyA have some effects to prevent progressive ischemia, capillary compromise and oedema.

Prediction of muscle viability after electrical burn necrosis.

In this preliminary study, Tc-99m MIBI, a muscle perfusion agent, was used to assess the viability of tissues in two patients with extensive high-tension electrical burns. This proved to be an easy and definitive diagnostic procedure and a practical solution to determining the level of amputation before surgery.

Evaluation of the effects of functional orthopaedic treatment on temporomandibular joints with single-photon emission computerized tomography.

The aims of this investigation were to evaluate the temporomandibular joints (TMJs) with single-photon emission computerized tomography (SPECT) in subjects treated with a mandibular advancement repositioning splint (MARS), and to compare the results with the total effect on dento-facial morphology. The study was undertaken on 17 Class II division 1 malocclusion subjects (nine males, eight females) with mandibular retrusion. Ten patients (five males, five females) formed the treatment group and seven (four males, three females) were used as the control. SPECT was performed only in the treatment group. Cephalometric evaluation showed significant increases in NAPog (P < 0.001) and SNB (P < 0.05) angles. Increased bone formation in theTMJs was analysed with the aid of pre- and post-treatment scintigraphic studies. The results indicate that new bone formation in the mandibular condyles seems to contribute to the increase in mandibular prognathism resulting from functional jaw orthopaedics.

Functional evaluation of renal transplants with scintigraphy.

A variety of techniques have been employed to assess renal function and its evolution after transplant surgery. Since initial perfusion studies are easy to perform, one may be tempted to rely on 99mTc-diethylenetriaminepentaacetic acid (DTPA) scanning alone. Some discrepancies have been observed between perfusion studies and clinical outcome of the renal transplant patients however. We therefore decided to evaluate both 99mTc-DTPA and 131I-hippuran renal scanning in 28 renal transplant patients. Sixty 99mTc-DTPA perfusion and 131I hippuran scintigraphies were performed using a same-day protocol. The examinations were repeated in 14 patients at weekly or monthly intervals to monitor the clinical trend of these patients. The results of this study indicate that, for early detection of the kidney problems, 131I-hippuran scintigraphy was superior to 99mTc-DTPA perfusion scans, but for the proper clinical management of renal transplant patients, both procedures should be utilized.

Registration and display of the combined bone scan and radiograph in the diagnosis and management of wrist injuries.

A system has been developed for the registration and combined display of the X-ray image and isotope bone scan. This system has been evaluated by prospectively studying 23 patients who were referred for suspected injury of the wrist. The registration system has an inherent precision for registration of about 1 mm. When patient positioning errors are included, this increases to about 4 mm. Two observers evaluated the sets of images prior to registration and after registration and combined display. They judged that in 16 out of 17 cases judged abnormal (observer 1) and 12 out of 18 cases judged abnormal (observer 2), the registration technique improved localization of a lesion. One case was rejected as registration was not possible due to incorrect positioning of the hand.

Evaluation of renal function in low-dose cyclosporine-treated patients using technetium-99m diaminocyclohexane: a cationic tubular excretion agent.

Technetium-99m diaminocyclohexane (DACH) is a new tubular agent excreted via a cationic transport mechanism, like cyclosporine-A (CsA). It is expected that 99mTc-DACH will permit effective assessment of tubular function in CsA-treated patients. To establish the pharmacokinetic characteristics of 99mTc-DACH and to ascertain whether this new agent is useful in CsA-treated patients, 11 healthy volunteers and 15 CsA-treated patients underwent renal imaging and clearance studies using 99mTc-DACH and chromium-51 ethylene diamine tetra-acetic acid (EDTA). 99mTc-DACH yielded satisfactory dynamic renal images in all participants. The mean plasma clearance of 99mTc-DACH was significantly greater than that of 51Cr-EDTA in volunteers (109.4¿19.7 ml/min versus 86.6 +/- 13.7 ml/min, P<0.05). However, the urinary excretion of 99mTc-DACH at 90 min was significantly lower than that of 51Cr-EDTA (46.1% +/- 9.3% versus 53.1% +/- 8.6%, P<0.05), most probably due to its partial parenchymal retention. The elimination half-life of 99mTc-DACH was significantly increased in CsA-treated patients in comparison to volunteers, and consequently the plasma clearance values were significantly suppressed in these patients, in contrast to 51Cr-EDTA and endogenous creatinine clearance values. In conclusion, our findings indicate that 99mTc-DACH, as a sensitive marker of cationic tubular function, could be used to monitor renal haemodynamics in patients receiving CsA treatment.