We present the case of a young woman with classical nodular sclerosing Hodgkin's lymphoma (clinical stage IIB). During staging work-up, intense gallium-67 ((67)Ga) accumulation in a left breast lump raised the suspicion of an extranodal deposit, but biopsy favoured a benign histology. A post-treatment (67)Ga scan showed complete remission of the disease with normal tracer uptake in the left breast. However, a few months after treatment, a faint left mammary concentration of (67)Ga was observed. The breast mass was excised and histopathology was consistent with fibroadenoma. This unusual presentation is a new addition to the literature on false-positive (67)Ga findings and chemotherapy-associated tracer changes.

Asymmetric I-123 MIBG uptake in salivary glands in children with cervical neuroblastoma has been reported previously, in association with Horner syndrome. We present the case of a 9-month-old male infant with a surgically excised right-sided cervical neuroblastoma, no manifestations of oculosympathetic paresis, and no visualization of the right-sided salivary glands in postoperative I-123 MIBG imaging. Six months later faint I-123 MIBG uptake was observed in the right parotid and submandibular salivary glands and this became more intense in subsequent scans. These findings are consistent with sympathetic denervation and reinnervation of the salivary glands and illustrate the plasticity of the sympathetic nervous system.

The lipophilic cationic radiotracer (99m)Tc-sestamibi, known to be concentrated within mitochondria, is widely used for myocardial perfusion and to a lesser extent for muscle metabolism imaging. However, the exact distribution pattern in skeletal muscle has not been yet studied in detail. The present study aims at investigating the (99m)Tc-sestamibi uptake in rat skeletal muscle and myocardium in relation to their metabolic characteristics.(99m)Tc-sestamibi was i.v. administered in twenty adult male Wistar rats and uptake, as percent of injected dose per tissue gram (% ID/g), in the myocardium, soleus, extensor digitorum longus and gastrocnemius muscles was assessed 2 hours post injection. Muscle uptake was also correlated with myocardial uptake, muscle weight and body weight. Skeletal muscle (99m)Tc-sestamibi uptake was a small (9-16 %) fraction of that found in myocardium (1.71+/-0.63 % ID/g). Among the three hindlimb muscles considered, the slow-oxidative soleus muscle showed the highest uptake (0.28+/-0.16 % ID/g). Metabolically diverse parts of the gastrocnemius muscle showed different uptake. Skeletal muscle uptake was positively correlated with myocardial uptake and both were negatively correlated with tissue and body weight. Evidence of matching exists between myocardial and muscle uptake, and both are size-dependent.

In radiolabeled leukocyte imaging, Tc-99m HMPAO has a significantly higher selectivity for eosinophils than neutrophils, but this may be clinically meaningful in disorders with eosinophilic infiltration. We present the case of a 2-year-old boy with infection who also developed drug-induced eosinophilic lung disease, as established later by bronchoalveolar lavage and discontinuation of the responsible antistaphylococcal agent. In the investigation of sepsis, diffusely increased pulmonary accumulation of Tc-99m HMPAO labeled leukocytes was observed. These findings were consistent with eosinophilic lung infiltration and underline the importance of clinical and laboratory data in the comprehensive interpretation of Tc-99m HMPAO labeled leukocytes scans.

Surgical ureteric injury is rare and often unsuspected for a long time. We present a child in whom an abdominal neuroblastoma was completely excised, but during surgery the left ureter was transected and anastomosed. One month later, during postoperative disease staging, abnormal (123)I-MIBG accumulation was observed in the left renal cortex and the left side of the abdomen. These findings were consistent with acute total obstruction and urinoma formation and were subsequently confirmed by renography and MRI. Despite treatment efforts, a significant amount of left renal mass and function were lost over the following months. These unusual findings are new additions to the literature regarding potential false-positive interpretations of (123)I-MIBG scans.

PURPOSE: To compare Tc-depreotide and Tl chloride SPET in the characterization of pulmonary lesions. METHODS: Fifty-seven pulmonary lesions from 33 patients suspected of malignancy in computed tomography, were assessed by Tc-depreotide and Tl early and delayed SPET imaging. Images were visually assessed and the tumour-to-normal (T/N) lung activity ratio for early (ER) and delayed (DR) scans and the retention index (RI), were calculated in every lesion. A final diagnosis was reached for all lesions, based either on histology or prolonged clinical and radiological follow-up. RESULTS: Twenty-three lesions were characterized as malignant and 34 benign. In visual analysis, all malignant lesions accumulated both tracers resulting in sensitivity and negative predictive values of 100%. However, false positive interpretations resulted in a specificity of 64.7% and 67.6% for Tc-depreotide and Tl, respectively. ER and DR of both agents and the RI of Tc-depreotide were significantly higher in malignant, compared to benign lesions. In defining thresholds of abnormality from ROC analysis, a significant increase in specificity was observed for both tracers in both scan phases (91.2% for all), as compared to visual analysis (P<0.01). There was no significant difference in the diagnostic performance between Tc-depreotide DR and Tl DR, although the former provided the highest T/N ratio. CONCLUSION: This study demonstrates that Tc-depreotide and Tl SPET are equally effective and may be useful in the non-invasive determination of lung malignancy. The specificity of both techniques is significantly improved by quantifying radiopharmaceutical accumulation in pulmonary lesions.

The solitary pulmonary nodule (SPN) is a relatively common imaging finding, often representing a diagnostic challenge. Radiological appearance, growth rate calculation during follow up and probability of malignancy assessment by the Bayes' theorem are widely used for identifying the nature of a SPN. Molecular imaging by fluoro-18 deoxy glucose positron emission tomography has revolutionised non-invasive diagnosis of lung cancer, but the low-cost, widely available conventional nuclear imaging modalities still remain valid in the field. We present a case of a growing SPN in a middle-aged male smoker. Growth rate assessment by sequential computed tomography scans, over a follow up period of five years, was suggestive of benign histology, while Bayesian analysis warranted histological confirmation of the nodule's nature. Imaging by both labelled somatostatin analogue technetium 99m-depreotide ((99m)Tc-depreotide) and thallium 201-chloride was almost exclusive of malignancy. The nodule was excised and histology showed a pulmonary hamartoma. We briefly discuss the relative role of invasive and non-invasive methods, with emphasis in conventional radionuclide molecular imaging, for the identification of the nature of SPN.

Brown adipose tissue (BAT) physiology and imaging have recently attracted considerable attention. BAT is characterized by both enhanced perfusion and increased mitochondrial activity;(99m)Tc-sestamibi is a lipophilic cationic tracer that concentrates in mitochondria. Data on the accumulation of (99m)Tc-sestamibi in BAT are currently lacking. This study investigates the in vivo (99m)Tc-sestamibi uptake in rat BAT.(99m)Tc-Sestamibi was administered in male Wistar rats of various age and body size and (99m)Tc-sestamibi uptake was in vitro measured in BAT and white fat (WF) along with cytochrome c oxidase (CCO) activity. Both (99m)Tc-Sestamibi uptake and CCO activity were higher in BAT than in WF (P < 0.05).(99m)Tc-Sestamibi uptake in both BAT and WF was negatively related to body weight (r =-0.96 and -0.89 respectively) as was the BAT / WF uptake ratio (r =-0.85). These data show a higher (99m)Tc-sestamibi uptake in BAT compared to WF, in agreement with the high mitochondrial content and respiratory activity of the former. The strong negative correlation between (99m)Tc-sestamibi uptake in BAT and body weight (negative allometry), is in accordance to increased needs of thermogenesis in smaller animals. Implications of increased (99m)Tc-sestamibi uptake in BAT in radionuclide imaging are also discussed.

Left ventricular diastolic filling is a fundamental constituent of cardiac performance. Diastolic function in both adults and children can be routinely assessed by radionuclide ventriculography (RNV). It has previously been shown that factors such as heart rate (HR) and age can significantly modify diastolic performance in adults, thus limiting the clinical applicability of RNV diastolic indices. The aim of this study was to investigate various factors that may affect diastolic function in childhood. Seventy-nine children, aged 40 days to 15 years, were enrolled in the study; their HR ranged from 45 to 160 beats per minute (bpm). All had intact cardiac function and were submitted to baseline RNV prior to chemotherapy initiation for malignancies. Using stepwise linear regression analysis, HR was identified as the major factor affecting RNV diastolic indices during growth. Applying univariate regression models, diastolic indices were corrected for a referrence HR of 100 bpm; this substantially reduced variability of RNV diastolic indices along age increments, allowing for the establishment of reference ranges. In conclusion, HR was shown to be the major determinant of RNV diastolic indices during growth. Adjustment for this variable alone can offer reference ranges for the assessment of left ventricular filling in childhood.