[Diagnostic value of (18)F-FDG PET/CT for solitary nodular-type bronchoalveolar carcinoma].

OBJECTIVE: To assess the value of (18)F-FDG PET/CT in the diagnosis of solitary nodular-type bronchoalveolar carcinoma (BAC). METHODS: The clinical and radiographic data were analyzed retrospectively in 30 patients with pathologically confirmed solitary nodular-type BAC who underwent (18)F-FDG PET/CT examinations between August, 2005 and December, 2006. The morphological and radioactive findings of the lesions were reviewed, and the maximum standard uptake values (SUVmax) were measured. The diagnostic accuracy of PET, PET/CT, and HRCT were analyzed. RESULTS: The (18)F-FDG SUV was markedly lower in BAC than in other well differentiated adenocarcinoma. In 19 of the BAC cases, PET showed a SUVmax of no less than 2.5, demonstrating positive changes. Of the total of 30 cases, 5 had ground glass opacity (GGO) changes, 3 exhibited mixed nodules with GGO changes around the lesions, and 22 cases presented with solid nodules. HRCT showed that BAC located often in the superior lobes of the bilateral lungs, mostly below the pleura in the surrounding lung field; the lesions were patchy or nodular with irregular shapes, showing lobulation in 22 cases, spiculation in 15 cases, pleural indentation in 21 cases, and vacuolar changes in 4 cases. The diagnostic accuracy of PET, PET/CT and HRCT for solitary nodular-type BAC was 36.67%, 93.33%, and 93.33%, respectively. CONCLUSION: The SUVmax of BAC provides only limited value for defining the nature of the lesions, but can serve as a general reference for assessing the disease activity. PET/CT, which allows both functional and imaging assessment, can be a valuable modality to reduce the misdiagnosis rate of BAC.

PET/CT imaging of delayed radiation encephalopathy following radiotherapy for nasopharyngeal carcinoma.

BACKGROUND: With the significant improvement in the survival of patients with nasopharyngeal carcinoma (NPC) undergoing radiotherapy and the growing availability of the sophisticated imaging modalities, the number of radiation encephalopathy (RE) cases relating to NPC radiotherapy is increasing. In this study, we investigated the metabolic and density changes of the compromised brain tissues during delayed RE using a positron-emission tomography-computed tomography (PET/CT) to provide clinical evidences for the diagnosis of delayed RE following radiotherapy for NPC. METHODS: The PET/CT manifestations and the clinical data of 53 pathologically confirmed NPC patients with delayed RE following radical radiotherapy and 15 healthy volunteers were investigated. The standardized uptake values (SUV) of the bilateral temporal lobes, the occipital lobe and the brain stem were measured respectively; and then the metabolic reduction rate of 88 temporal lobes and 13 brain stems were calculated for a statistical comparison between the two groups. RESULTS: The earliest case of delayed RE in the investigated patients occurred 1.5 years after radiotherapy. Delayed RE frequently involved the inferior temporal lobe. For patients with delayed RE confirmed by clinical symptoms and imaging findings, PET maintained a 100% coincidence rate with CT; however, in the 25 temporal lobes of the 35 delayed RE patients, PET revealed obvious hypometabolic changes whereas CT displayed normal density. The incidence of brain stem metabolic reductions was 24.5% (13/53) in the investigated patients, including 4 patients with hypometabolic changes shown by PET and negative finding shown by CT. The incidence of granuloma adjacent to the hypometabolic region in the temporal lobe was 12.5% (11/88). CONCLUSION: Delayed RE patients exhibit significant hypometabolic changes in the inferior temporal lobe, captured by PET much earlier than by CT. PET/CT offers a valuable means for the diagnosis of delayed RE in subacute stages and granuloma formation.

[Effects of lead acetate on expression of brain-derived neurotropic factor and P75NTR in rat brain].

OBJECTIVE: To study the effects of lead acetate on the expression of brain-derived neurotropic factor (BDNF) and its receptor P75NTR in rat brain. METHODS: Lead acetate was given to SD rats by intraperitoneal injection (ip) for 5 days at the dosage of 25, 50 and 100mg/kg body weight respectively. The contents of lead in serum, cerebral cortex and hippocampus were measured by atomic absorption spectrophotochemistry. The levels of BDNF mRNA and protein expression in cerebral cortex and hippocampus were observed by RT-PCR and immunohistochemistry, respectively. The levels of P75NTR protein expression in rat brain were measured by immunohistochemistry. RESULTS: Compared with the control, the contents of lead were significantly increased in serum, cerebral cortex and hippocampus in the treatment groups respectively (P < 0.01, P < 0.05). The BDNF mRNA expression in the cerebral cortex (0.52 +/- 0.05, 0.33 +/- 0.03) and hippocampus (0.77 +/- 0.10, 0.92 +/- 0.08) of 50, 100 mg/kg treated groups was significantly higher than that of the control group (0.52 +/- 0.05, 0.33 +/- 0.03), respectively (P < 0.05). The results of immunohistochemistry showed that the area density of BDNF protein in cerebral cortex of every treatment group (0.040 +/- 0.027, 0.048 +/- 0.027, 0.086 +/- 0.040) was significantly increased whereas the average gray value (187.11 +/- 11.15, 180.53 +/- 5.82, 180.15 +/- 8.01) was significantly lower than that of the control (0.026 +/- 0.005, 204.98 +/- 3.45) (P < 0.05, P < 0.01). The area density of BDNF protein in hippocampus of every treatment group was 0.040 +/- 0.027, 0.048 +/- 0.027, 0.086 +/- 0.040, respectively, which was significantly increased compared with the control (0.045 +/- 0.019, P < 0.05). The average gray value of BDNF protein in hippocampus (181.03 +/- 5.16, 171.25 +/- 12.65) of 50, 100 mg/kg were significantly lower than that of the control (198.98 +/- 6.40, P < 0.01). There was no positive expression of P75NTR protein in the control and 25 mg/kg body weight groups. The positive expression of P75NTR protein was detected in 50 and 100 mg/kg body weight groups. CONCLUSION: Lead can increase the BDNF and P75NTR expression in rat brain which might play an important role in the neural damage and repair.