False positive 18F-FDG PET scan in adrenal oncocytoma.

18F-FDG whole-body positron emulsion tomography (18F-FDG PET) has become an established imaging modality for a variety of cancers. Today, 18F-FDG PET is utilized to differentiate benign from malignant non-functioning adrenal masses. In this report, a 25-year-old woman presented with a 2-month history of left flank pain. Abdominal CT revealed a left 6.5 x 4.5 cm adrenal mass with regular margins and focal calcification. To make a differential diagnosis, 18F-FDG PET was performed. Preoperative laboratory studies showed that the mass was non-functioning. A left adrenalectomy was performed through a left subcostal incision. The final pathologic evaluation revealed adrenal oncocytoma. We present the disassociation between preoperative 18F-FDG PET and pathologic findings of a benign adrenocortical oncocytoma.

Gastric emptying time in renal transplant recipients treated with cyclosporine.

Gastric emptying time (GET) appears to be a rate-limiting factor in the absorption of cyclosporine-A (CsA) and may be responsible for intra- and interpatient variability of CsA bioavailability. Few studies have assessed gastric motility after renal transplantation. The purpose of this study was to evaluate gastric emptying of semi-solid material in stable renal transplant patients with reference to blood CsA levels. The GET of semi-solids (GET t(1/2), half emptying time) was measured in 16 transplant recipients who were taking CsA (Neoral), prednisolone and azathioprine (or mycophenolate mofetil). The GET (t(1/2)) measured by radionuclide methods, was analyzed with reference to the daily CsA doses, levels of CsA (C(0)), and serum creatinine concentrations. The mean GET (t(1/2)) was 89.1 +/- 26.4 minutes. Twelve patients exhibited delayed gastric emptying with a mean CsA level of 171.8 +/- 56 ng/mL and a mean dose of 4.1 +/- 1.1 mg/kg/d. The GET (t(1/2)) was not significantly correlated with the serum creatinine levels, the time since transplantation, or the CsA concentration. In addition, the correlation between the mean daily CsA dose and the GET (t(1/2)) was only weakly positive, (r =.33, P =.2) and therefore, statistically insignificant. In conclusion, it could not be ascertained whether a higher dose of CsA delays gastric emptying or whether patients with delayed emptying require higher doses of CsA. However, it is believed that determining the GET after transplantation helps in the adjustment of immunosuppressant doses.

The role of thrombophilic risk factors in the severity of pulmonary thromboembolism.

High plasma factor-VIIIc concentration, presence of factor-V 1691 G-A (FVL) and prothrombin20210A (PT20210A) mutations were shown to be significant risk factors for venous thromboembolism (VTE) and recurrent VTE. The objective of this study was to investigate the role of these thrombotic risk factors in the severity of pulmonary thromboembolism (PTE). The plasma concentrations of factor VIIIc, presence of FVL and PT20210A mutations were studied in 32 patients with PTE. Eleven of the patients had documented recurrent VTE. Lung perfusion scans were scored according to the percentage of vascular obstruction. Patients who had a pulmonary vascular obstruction score (PVOs) >50% were compared to those with PVOs <50%. There was no significant difference between the patients with PVOs >50% and those with PVOs <50%, with regard to the presence of FVL and PT20210A mutation. However, patients with PVOs >50% had a significantly higher factor-VIIIc concentration than those with PVOs <50% (factor-VIIIc levels were 253.3 +/- 29.1 International Units (IU) x dL(-1) and 138.5 +/- 16.2 IU x dL(-1), respectively; p<0.005). Factor-VIIIc concentrations were significantly correlated with PVOs (r=0.52, p<0.005). Patients with recurrent VTE had significantly higher factor-VIIIc concentrations than those in which it occurred for the first time (factor-VIIIc concentrations were 232.6 +/- 30.9 IU x dL(-1) and 158.3 +/- 20.6 IU x dL(-1), respectively; p<0.05). The authors conclude that in addition to being a risk factor for venous thromboembolism, high factor-VIIIc concentration is an important factor in the severity of pulmonary thromboembolism.

Increased accumulation of Tl-201 in monostotic Paget's disease of the patella: evaluation with quantitative analysis.

Monostotic Paget's disease of the patella was detected with Tc-99m MDP and Tl-201 scans. Diffuse intense uptake of MDP in the left patella was observed on the blood-pool and late phases of the bone scan. Tl-201 imaging was performed to differentiate a malignant process and showed diffuse marked accumulation at the same site. Semiquantitative analysis of the patella region on both Tc-99m MDP and Tl-201 scans did not support a diagnosis of cancer. Radiographs showed the features of Paget's disease of the bone. Findings of a pathologic evaluation were compatible with the diagnosis of osteitis deformans. This case represents the unusual skeletal involvement of monostotic Paget's disease of the bone in the patella. Tl-201 accumulation in the Paget's lesion was suggested to be caused by increased metabolic activity of the lesion but was not indicative of a malignant process.

Low dose dobutamine echocardiography is more predictive of reversible dysfunction after acute myocardial infarction than resting single photon emission computed tomographic thallium-201 scintigraphy.

To directly compare dobutamine echocardiography and resting single photon emission computed tomographic (SPECT) thallium-201 (Tl-201) scintigraphy for the detection of reversible dysfunction, 64 patients underwent dobutomine echocardiography (baseline, low dose 5 and 10 mg/kg/min, and peak dose), rest Tl-201 scintigraphy (3 mCi - 15 minute and 3- to 4-hour SPECT imaging), and coronary angiography during the first week after acute myocardial infarction. Follow-up echocardiography was performed 4 to 8 weeks after discharge. Wall thickening improved at follow-up in 52% (207 of 399) of the dysfunctional segments. By receiver operating characteristic analysis, biphasic responses and sustained improvement during dobutamine echocardiography were more accurate (p < 0.01) than Tl-201 uptake by SPECT scintigraphy for reversible dysfunction. The greater accuracy of dobutamine echocardiography resulted from higher accuracy in akinetic segments, Q wave infarction, and multivessel coronary artery disease. In conclusion, dobutamine echocardiography was more accurate than resting SPECT Tl-201 scintigraphy for reversible dysfunction after acute myocardial infarction.

Effect of gallium nitrate therapy on Ga-67 scintigraphic detection of lymphoma: case report.

Ga-67 and abdominal CT scans of a 72-year-old woman who had malignant lymphoma before, during, and after gallium nitrate/hydroxyurea combination therapy are presented. Disappearance of Ga-67 uptake by the tumor during this treatment despite continuing CT evidence of disease and reappearance of Ga-67 scan abnormalities after cessation of therapy suggests that caution should be exercised when interpreting results of Ga-67 scintigraphy for the detection of tumor viability during gallium nitrate/hydroxyurea therapy.

The value of Tc-99m Nanocolloid scintigraphy in the evaluation of infected total hip arthroplasties.

The early diagnosis of loosening is very important, since it provides a chance to protect the bone structure by means of a good postrevision outcome. Although the delayed stage of infected loosenings can easily be detected by clinical presentations, significant laboratory data and plain X-rays, diagnosis becomes a problem in the early stage. In this study the value of Tc-99m Nanocolloid (NCol) scintigraphy in the diagnosis of infected loosenings was evaluated in 28 patients with painful total hip arthroplasty and 10 controls without any complaint after total hip arthroplasty, by comparing this method with laboratory data, plain X-rays and 3-phase Tc-99m methylene diphosphonate (MDP) scintigraphy. Tc-99m NCol scintigraphy was found out to be a very valuable method with 100% sensitivity, 84% specificity in the diagnosis of infected prosthesis and it was superior to laboratory data, plain X-rays and 3-phase Tc-99m MDP scintigraphy, but requires to be evaluated in conjunction with plain X-rays for more information and in order to prevent false positive results.

Intraosseous meningioma: appearance on bone scintigraphy over five years.

While meningiomas are common intradural tumors, such lesions only rarely arise outside of the meninges. All meningiomas, however, may slowly enlarge causing concern for malignancy. We report the appearance of an intraosseous meningioma in the patient with a history of breast carcinoma where the lesion progressively enlarged over a period of 5 yr to reach approximately three times the original size.

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.

Dual radioisotopic study: a technique for the evaluation of vasculogenic impotence.

Arterial and venous systems are the main points for the evaluation of vasculogenic impotence. To evaluate both of these systems in the same study we propose a dual radioisotopic study in which 99mtechnetium (99mTc) and 133xenon (133Xe) were used. The changes in 99mTc and 133Xe radioactivities administered intravenously and intracavernously, respectively, were monitored before and after intracavernous papaverine injection. These changes were determined as time activity curves, which were generated from the region of interest over the penis. A 99mTc penogram index derived from the 99mTc time activity curve was significantly different in the control and arteriogenic impotence groups (131.67 +/- 74.6 versus 62.94 +/- 51.6, p less than 0.01). A meaningful correlation between 99mTc penogram index results and duplex ultrasonographic findings were observed (r = 0.905). 133Xe penogram index, derived from the 133Xe washout curve was significantly different in the control and venogenic impotence groups (-25.65 +/- 24.9 versus -56.09 +/- 13.4, p less than 0.01). Also, a meaningful correlation was obtained between pharmacocavernosometry and 133Xe penogram index results of venogenic impotent patients (r = 0.86). These findings suggest that the dual radioisotopic study will be a useful technique in the evaluation of the entire vascular system of the penis, since it is a noninvasive method.

Increased accumulation of hexakis (2-methoxyisobutylisonitrile)technetium(I) in osteosarcoma and its metastatic lymph nodes.

Scintigraphy using hexakis (2-methoxyisobutylisonitrile) technetium (I) [Tc-MIBI] was performed in a patient with osteosarcoma of the right tibia. Increased accumulation of Tc-MIBI was observed in the primary site of the tumor as well as in metastatic lesion of the right inguinal lymph nodes, which were later confirmed by biopsy.

Evaluation of 99mTc-labelled vitamin K4 as an agent for testicular imaging.

Vitamin K4 was labelled with 99mTc with an efficiency higher than 97%. The compound was stable up to 24 h at room temperature, and its biodistribution in NMRI mice indicated its in vivo stability. Blood radioactivity levels were high over a wide range. 10% of the injected activity remained in blood after 24 h. Excretion was mostly via kidneys. Only the liver and kidneys concentrated appreciable amounts of radioactivity. Testis/soft tissue ratios were 1.4 and 1.57 at 6 and 24 h, respectively. Testis/blood ratios were lower than 1. In vitro studies with mouse blood indicated that 33.9 +/- 9.6% of the radioactivity was associated with RBCs; it was washed out almost completely with saline. Protein binding was 28.7 +/- 6.3% as determined by TCA precipitation. Blood clearance of 99mTc-K4 in normal subjects showed a slow decrease of radioactivity, reaching a plateau after 16 h at 20% of the injected activity. In scintigraphic images in men the testes could be well visualized. The right/left testis ratio was 1.08 +/- 0.13. Testis/soft tissue and testis/blood activity ratios were highest at 3 h. These ratios were higher than those obtained with pertechnetate at 20 min post injection. 99mTc-K4 appears to be a promising radiopharmaceutical for the scintigraphic visualization of testes.