The impact of sentinel lymph node mapping with hybrid single photon emission computed tomography/computed tomography in patients with melanoma. Comparison to planar radioisotopic lymphoscintigraphy.

We studied the diagnostic value of 16 slices of single photon emission computed tomography (SPECT)/computed tomography (CT) in the anatomical localization, image interpretation and extra-sentinel lymph nodes (SLNs) detection compared to dynamic and static planar radioisotopic lymphoscintigraphy (PLS) in patients with melanoma. Eighty-two patients with melanoma underwent dynamic PLS, static PLS and SPECT/CT. Data were obtained using a dual head SPECT/CT 16 slices γ-camera. We evaluated the number and localization of SLNs detected with each imaging method. SPECT/CT demonstrated 48 additional SLNs in comparison with PLS in 29 patients. In five truncal and seven head-neck lesions, dynamic and static PLS failed to detect the SLNs found on SPECT/CT (false negative). In one case of truncal and one case of lower limb melanoma, the foci of increased activity interpreted on PLS as possible SLNs were confirmed to be non-nodal sites of uptake on SPECT/CT (false positive). PLS underestimated the number of SLNs detected, whereas SPECT/CT revealed higher agreement compared to the respective number from histological reports. SPECT/CT showed a better prediction of the number of SLNs and higher diagnostic parameters in comparison to planar imaging. SPECT/CT is an important complementary diagnostic modality to PLS, that improves detection, preoperative evaluation, anatomical landmarks of SLNs and surgical management of patients with melanoma.

Does lung perfusion scintigraphy continue to have a role in the clinical management of patients suspected of pulmonary embolism in the CT pulmonary angiography era?

OBJECTIVE: Acute pulmonary embolism (PE) is a life-threatening disorder with high mortality. A prompt diagnosis and treatment is essential for reducing the mortality rate. The purpose of the study is to evaluate if lung perfusion scintigraphy (LPS) continues to have a role in the clinical management of patients suspected of pulmonary embolism in the CT pulmonary angiography (CTPA) era. METHODS: For this study, 1183 patients who had been subjected to LPS were retrospectively evaluated and classified into the following groups: A (positive LPS), B (negative LPS) and C (indeterminate LPS). Patients were further classified into A1 ('PE likely' and LPS-negative), B1 (PE unlikely and LPS-positive) and C1 (PE likely and indeterminate LPS) by combining the LPS findings and the clinical pretest probability (cpp). Subgroups A1, B1 and C1 underwent additional CTPA. RESULTS: Groups A, B, and C included 1086/1183, 69/1183 and 28/1183 patients, respectively. The proportion of patients with inconsistent cpp LPS findings who underwent additional CTPA was 106/1183 patients: subgroup A1 (n = 73), B1 (n = 21), and C1 (n = 12). In subgroup A1, CTPA was negative in 61/73, non-diagnostic in 12/73 and positive in 0/73 patients. In subgroup B1, CTPA excluded PE in 2/21, non-diagnostic in 3/21 and positive in 16/21 patients. In group C1, CTPA was negative in 8/12, positive in 2/12 and non-diagnostic in 2/12 patients. CONCLUSION: In the CTPA era, LPS continues to have a role in the clinical management of patients suspected of PE.

Rare presentation of occult medullary carcinoma of the thyroid as a mediastinal mass.

OBJECTIVE: To describe a rare case of occult (<1 cm in diameter) medullary thyroid carcinoma (MTC) in a 45-year-old woman, presenting as an asymptomatic mediastinal mass. DESIGN: The diagnostic methodology included laboratory measurements of relevant biochemical and hormonal parameters including calcitonin (CT), carcinoembryonic antigen (CEA) and chromogranin A, and imaging techniques including ultrasound (U/S), computed tomography (C/T), magnetic resonance imaging (MRI) and radio labeled somatostatin analog ((111)In-DTPA-octreotide). RESULTS: Chest CT revealed a mediastinal mass measuring 5 cm in diameter abutting the right thyroid lobe. CEA was elevated and an association with thyroid malignancies was considered. CT was found to be markedly elevated, pointing to the diagnosis of MTC metastatic to the mediastinum. The patient underwent total thyroidectomy, lymph node dissection and removal of the mediastinal mass. Histological examination revealed MTC of the right thyroid lobe measuring 0.5 cm, metastatic to regional and superior mediastinal lymph nodes. CONCLUSIONS: Occult MTC can infrequently present as an asymptomatic mediastinal mass. Elevated serum CT and CEA along with imaging techniques leads to the correct diagnosis and surgical management of the disease.

The role of scintigraphy in the evaluation of brain malignancies.

The gold standard for diagnosis of primary brain tumors is histopathological evaluation of the obtained tissue samples. Nevertheless, anatomical and functional imaging modalities have a determinative role in the precise localization and characterization of these lesions. In this review we focus on the clinical applications and future potentials of nuclear medicine procedures. Several single photon emission tomography (SPET) tracers such as thallium-201 chloride ((201)TlCl(2)), technetium-99m ((99m)Tc) methoxyisobutylisonitrile (MIBI), (99m)Tc-tetrofosmin (TF) and 3-[iodine-123] iodo-α- methyl-L-tyrosine ((123)I-IMT) have been utilized in the diagnosis of brain tumors. Positron emission tomography (PET) alone or fused with computed tomography (CT), are widely acceptable methods in oncology, at present and for the future.

Role of scintigraphy in inflammatory bowel disease.

The diagnosis of inflammatory bowel disease (IBD) depends on direct endoscopic visualization of the colonic and ileal mucosa and the histological study of the obtained samples. Radiological and scintigraphic methods are mainly used as an adjunct to endoscopy. In this review, we focus on the diagnostic potential of nuclear medicine procedures. The value of all radiotracers is described with special reference to those with greater experience and more satisfactory results. Tc-99m hexamethylpropylene amine oxime white blood cells remain a widely acceptable scintigraphic method for the diagnosis of IBD, as well as for the evaluation of disease extension and severity. Recently, pentavalent Tc-99m dimercaptosuccinic acid has been recommended as an accurate variant and a complementary technique to endoscopy for the follow-up and assessment of disease activity. Positron emission tomography alone or with computed tomography using fluorine-18 fluorodeoxyglucose appears to be a promising method of measuring inflammation in IBD patients.

Is there a role for Tc-99m (V) DMSA scintigraphy in ischemic colitis?

AIM: To evaluate the role of pentavalent Tc-99m dimercaptosuccinic acid [Tc-99m (V) DMSA] in the diagnosis of ischemic colitis. METHODS: Fourteen patients with endoscopically and histologically confirmed ischemic colitis were included in the study. Tc-99m (V) DMSA scintigraphy was performed within 2 d after colonoscopy. Images were considered positive when an area of increased activity was observed in the region of interest and negative when no abnormal tracer uptake was detected. RESULTS: In 3 out of the 14 patients, Tc-99m (V) DMSA images showed moderate activity in the bowel. The scintigraphic results corresponded with the endoscopic findings. In the other 11 patients, no abnormal tracer uptake was detected in the abdomen. CONCLUSION: Besides the limited number of patients, Tc-99m (V) DMSA could not be considered as a useful imaging modality for the evaluation of ischemic colitis.

Myocardial sympathetic innervation in patients with impaired glucose tolerance: relationship to subclinical inflammation.

AIM: This study was designed to assess cardiac adrenergic nerve activity, using iodine (I)-123-labeled metaiodobenzylguanidine (MIBG), in patients with impaired glucose tolerance (IGT) and to investigate its relation to circulating levels of proinflammatory cytokines. METHODS: We studied 22 patients with IGT (aged 34-68 years) and 18 age-matched healthy controls, using I-123 MIBG cardiac imaging. The early (10 min) and late (4 h) heart to mediastinum MIBG uptake (H/M) ratio and washout were calculated. Levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-a), and its soluble receptor [soluble TNF receptor II (sTNFRII)] were measured by immunoassay of blood samples from patients and controls. RESULTS: The early and late MIBG uptake was lower (both P<.001) and the WR was higher (P<.001) in patients than in controls. The analysis showed innervation defects in 20 of the 22 patients. Nearly half (45.4%) showed severe adrenergic innervation defects in both the inferior wall and the apex. Regarding cytokines, patients showed significantly elevated TNF-a (P=.005), sTNFRII (P<.001), and IL-6 (P<.001) levels compared to controls. IL-6 and sTNFRII were found to correlate with the WR (r=0.468, P=.028 and r=0.455, P=.034, respectively). CONCLUSION: Patients with IGT show reduced MIBG cardiac uptake with a segmental pattern. The reduced cardiac sympathetic innervation was related to the elevated proinflammatory cytokine levels and could be considered an index of early atherosclerotic process in these patients.

Active inflammatory bowel disease: head-to-head comparison between 99mTc-hexamethylpropylene amine oxime white blood cells and 99mTc(V)-dimercaptosuccinic acid scintigraphy.

PURPOSE: Evaluation and comparison between pentavalent 99mTc dimercaptosuccinic acid (99mTc(V)-DMSA) and 99mTc-hexamethylpropylene amine oxime white blood cell (99mTc-HMPAO WBC) scintigraphy in the detection and assessment of disease activity in patients with active inflammatory bowel disease (IBD). MATERIALS AND METHODS: 99mTc(V)-DMSA scintigraphy was performed in 23 patients with active IBD and true positive 99mTc-HMPAO WBC scintigraphy. Images were considered positive when an area of increased uptake was observed. To assess severity of IBD, semi-quantitative analysis was included with reference to the uptake in the iliac crest. Comparison with endoscopic, radiological and clinical data was performed. RESULTS: The diagnostic accuracy of 99mTc-HMPAO WBC and 99mTc(V)-DMSA was 91% and 84%, respectively. A significant correlation between the findings of both radioisotopic methods and scintigraphy score was demonstrated. Endoscopic findings were significantly correlated with scintigraphic results. Kappa statistics showed a moderate to good agreement between the two scintigraphic methods. Two patients (8.8%) had negative findings with 99mTc(V)-DMSA scintigraphy (false negative results). CONCLUSION: 99mTc(V)-DMSA compared to 99mTc-HMPAO WBC could provide a simple, non-invasive alternative method for the assessment of disease activity, although it is slightly inferior to 99mTc-HMPAO WBC scintigraphy especially in the evaluation of disease localization in IBD patients.

[Nuclear Medicine in the diagnosis of lower gastrointestinal bleeding].

Lower gastrointestinal bleeding appears to be a frequent problem in the every day practice. The exact localisation of the bleeding site plays a major role in treatment planning. Nuclear Medicine imaging techniques allow the diagnosis of ectopic gastric mucosa-Meckel's diverticulum (MD) and the extravasation of red blood cells. Meckel's diverticulum is the most frequent congenital anomaly of the gastrointestinal system moreover bleeding seems to be the most important clinical symptom during childhood. Scintigraphy using technetium-99m pertechnetate ((99m)TcO(4)(-)) is the method of choice for the diagnosis of ectopic gastric mucosa in MD. The use of this test in children is of high diagnostic accuracy, with a sensitivity of 85%-95% and specificity of 90%-95%. In adults, lower gastrointestinal bleeding is commonly caused by tumors, colitis, dysplasias or polyps, while MD is rare. Scintigraphic demonstration of active lower gastrointestinal bleeding contributes to risk-stratification, to prognosis, appropriate timing for angiography and to planning of surgical intervention. (99m)Tc labelled erythrocytes and (99m)Tc sulphur colloid are commonly used radiopharmaceuticals each having its own indications and used for the diagnosis of active bleeding. Moreover delayed imaging is possible using (99m)Tc labelled erythrocytes, enabling the diagnosis of intermittent bleeding. Careful interpretation of the scintiscan images is essential to avoid numerous pitfalls. The indications for using the specific nuclear medicine technique as above, for the diagnosis of lower gastroinstestinal bleeding and the indications for using other methods besides those of nuclear medicine are described.