[Value of positron emission tomography-computed tomography in the diagnosis of mediastinal lymph node metastasis of non-small cell lung cancer].

OBJECTIVE: To investigate the value of positron emission tomographic-computed tomographic scanning (PET/CT) in the diagnosis of mediastinal lymph node metastasis in patients with non-small cell lung cancer and the application of PET/CT in the clinical staging of NSCLC. METHODS: A hundred and fifty-eight patients with NSCLC undergoing surgical resection and mediastinoscopy received preoperative examinations with PET/CT. All the patients underwent mediastinal lymph node dissection or sampling, and the pathological results were compared with the imaging findings. The diagnostic sensitivity, specificity, positive and negative predictive values, and accuracy of CT and PET/CT were compared. RESULTS: Final histology was available for 937 lymph node samples (N1, N2, and N3) from 158 patients during mediastinoscopy or surgical resection. The sensitivity, specificity, and positive and negative predictive values of CT for identifying mediastinal lymph node involvement were 51.0%, 76.1%, 49.0%, and 77.6%, respectively, with an diagnostic accuracy of 68.4%. The sensitivity, specificity, and positive and negative predictive values of PET/CT were 83.7%, 89.0%, 77.4%, and 92.4%, respectively, with a diagnostic accuracy of 87.3%. CONCLUSION: Mediastinoscopy is essential for patients with positive findings of mediastinal lymph node involvement by PET/CT, but might not be necessary in negative patients.

[Relationship between fluorodeoxyglucose uptake and vascular endothelial growth factor in early-stage nasophygeal carcinoma].

OBJECTIVE: To study the overexpression of vascular endothelial growth factor (VEGF) and fluorine-18 fluorodeoxyglucose (FDG) uptake in early-stage nasopharyngeal carcinoma (NPC) and evaluate their relationship. METHODS: FDG positron emission tomography (PET) was performed in forty patients with stage I and stage II NPC. The maximum and mean standard uptake values (SUVmax and SUVmean, respectively) were measured in each patient, and the expression of VEGF was measured on paraffin sections using immunohistochemistry. RESULTS: The FDG uptake in the patients were 9.45-/+1.87 (SUVmax) and 6.04-/+1.09 (SUVmean), 8.95-/+1.91 (SUVmax) and 6.04-/+1.09 (SUVmean) in stage I patients, and 11.55-/+1.70 (SUVmax) and 7.98-/+1.1 (SUVmean) in stage II patients. The FDG uptake of stage II patients was higher than that of stage I patients. The FDG uptake of non-keratinizing differentiated carcinoma was 9.74-/+1.82 (SUVmax) and 6.82-/+1.23 (SUVmean) and 10.44-/+2.16 (SUVmax) and 6.68-/+1.35 (SUVmean) in non-keratinizing undifferentiated carcinoma, showing no significant differences between them (SUVmax: t=1.230, P>0.05; SUVmean: t=0.346, P>0.05). The VEGF-positive cells were 60.80% in the tumor. A correlation between VEGF expression and FDG uptake in he tumor was noted (r=0.460, P=0.03). CONCLUSION: VEGF overexpression is correlated to FDG uptake in patients with early-stage NPC. The SUV value reflects the glucose metabolism of NPC, and also shows the degree of oxygen insufficiency in the tumor tissue.

[Analysis of standard uptake values of 18F-FDG PET/CT in relation to pathological classification and clinical staging of nasopharyngeal carcinoma].

OBJECTIVE: To explore the relation of the standard uptake values (SUV) of 18F-fluorodexygl-gucose (18F-FDG) PET/CT and the pathological classification and clinical staging of nasopharyngeal carcinoma (NPC). METHOD: Whole body 18F-FDG PET imaging was performed in 32 patients with pathologically confirmed NPC, who received no previous treatment. The regions of interest (ROI) covering the pharyngeal and cervical lesions were defined along the margins of the lesion, and the lesion volume and the SUVs were calculated. RESULTS: The SUVs in stage I, II, III, and IV patients were 4.50-/+0.42, 5.62-/+1.44, 7.33-/+1.50, and 8.24-/+2.16, respectively, showing significant differences between them (P < 0.05). In patients in stage T1, T2, T3, and T4, the SUVs increased significantly in advanced stageds (2.56-/+1.05, 3.72-/+0.60, 6.87-/+1.07, and 9.70-/+0.70, respectively, P < 0.05). The SUVs were not significantly different in patients in stages N1, N2, and N3, differed significantly between lymph nodes > 6 cm in size and those < or = 6 cm (5.92-/+1.51 vs 3.48-/+1.31, P < 0.05). The SUV in poorly differentiated squamous carcinoma was significantly lower than that in undifferentiated carcinoma (5.58-/+1.48 vs 8.41-/+1.71, F = 1.3323, P = 0.01). CONCLUSIONS: The SUV is not associated with the clinical staging of NPC, but is correlated to the T staging of NPC. Though irrelevant to the N staging of NPC, the SUV is correlated to the size of the lymph nodes, and also related to the degree of differentiation of NPC.

[PET/CT-based classification of delayed radiation encephalopathy following radiotherapy for nasopharyngeal carcinoma].

OBJECTIVE: To investigate positron-emission tomography-computed tomography (PET/CT) findings of radiation encephalopathy (RE) following radiotherapy for nasopharyngeal carcinoma (NPC), observe the metabolic changes of the compromised brain tissues, and postulate the clinical classification of RE to provide reference for its diagnosis. METHODS: This study included 53 pathologically confirmed NPC patients who received previous radical radiotherapy, and the diagnosis of RE was established according to the clinical manifestations and CT/PET findings. All the patients underwent PET/CT whole-body and head scans, and the image data were evaluated along with the clinical data of the patients. RESULTS: RE most frequently involved the lateral or bilateral inferior temporal lobes. PET identified hypometabolic changes in the bilateral temporal lobes of 35 patients (70 lobes) and in the lateral temporal lobe of 18 patients (18 lobes). According to the PET/CT findings, the lesions were classified into 3 types, namely the oedema type (56 temporal lobes), liquefactive necrosis type (10 temporal lobes), and atrophic calcification type (22 temporal lobes). One patient with oedema type lesion received neurotrophic treatment and recovered completely with normal brain tissue density and metabolism, but the oedema type lesions in 2 patients progressed into to atrophic calcification type; the liquefactive necrotic lesions in another 2 patients also progressed into atrophic calcification type. CONCLUSION: RE patients exhibit significant hypometabolic changes in the inferior temporal lobe on PET. According to the findings by PET/CT, RE can be classified into the oedema type, liquefactive necrosis type, and atrophic calcification type, and lesions of the former two types may progress into the third type.

Resting Chest Pain, Negative Treadmill Exercise Electrocardiogram, and Reverse Redistribution in Dipyridamole Myocardial Perfusion Scintigraphy Might be the Features of Coronary Artery Spasm.

BACKGROUND: Coronary artery spasm usually attacks while at rest and the diagnosis depends on provoking tests which mostly are invasive, expensive and not practical. Previous investigations demonstrated that in most patients with coronary artery spasm, treadmill exercise electrocardiography (TEEC) did not induce any ischemic changes, and myocardial perfusion scintigraphy (MPS) showed reverse redistribution (RR). HYPOTHESIS: Combination of resting chest pain, negative TEEC and RR might be a rational noninvasive set to predict coronary artery spasm. METHODS: Patients with chest pain at rest, no significant coronary artery stenosis, and willing to undergo acetylcholine test were included. TEEC, dipyridamole and rest thallium-201 MPS were performed before or after coronary angiography. The patients were divided into spasm and nonspasm groups by acetylcholine test. The clinical features and results of TEEC and MPS were compared between the spasm and nonspasm groups. RESULTS: Acetylcholine test was performed in 92 patients and coronary artery spasm was successfully provoked in 68 patients. Positive TEEC was induced in only 4 patients in the spasm group. RR was present in totally 77 patients and 68 of them were from the spasm group. By a combination of resting chest pain, negative TEEC and RR to diagnose coronary artery spasm, the sensitivity and specificity were 94% and 96% respectively. CONCLUSION: Combination of resting chest pain, negative TEE and RR appears to be a rational noninvasive set to predict coronary artery spasm.

[The differential diagnostic value and significance of combined heart stress tests in patients with atypical chest pain].

OBJECTIVE: To investigate the value of stress electrocardiography (S-ECG) and stress myocardial perfusion scintigraphy (S-MPS) in the differential diagnosis of patients with atypical chest pain. METHODS: Patients with atypical chest pain were undergone S-ECG, S-MPS, coronary angiography and coronary artery spastic provocation with intracoronary acetylcholine test. The final diagnoses of those patients were coronary heart disease, coronary spasm, coronary artery muscular bridge, microvascular angina pectoris and chest pain with non-coronary heart disease. Those patients were grouped by final diagnoses to retrospectively compare the results of S-ECG and S-MPS between groups. RESULTS: Totally 186 patients with integrated data were included. The final diagnoses were coronary artery stenosis (above 50% stenosis in diameter) in 20%, coronary artery spasm in 27%, coronary artery muscular bridge in 14%, microvascular angina pectoris in 5%, and chest pain with non-coronary artery disease in 34%. The sensitivity and specificity to diagnose ischemic coronary artery disease (including coronary stenosis, coronary artery muscular bridge and syndrome X but not coronary artery spasm) were 92% and 65% in S-ECG, 62% and 79% in S-MPS, respectively. Combination of atypical chest pain, negative S-ECG and reversal redistribution of S-MPS was an accurate non-invasive method to diagnose coronary artery spasm with sensitivity of 94% and specificity of 96%. CONCLUSIONS: Most of patients with atypical chest pain have organic or functional ischemic coronary artery disease. Combination of heart stress tests are helpful to differentiate the etiology of atypical chest pain.

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.