Improving accuracy of 18F-fluorodeoxyglucose PET computed tomography to diagnose nodal involvement in non-small cell lung cancer: utility of using various predictive models.

PURPOSE: To determine predictive models (PM) that could improve the accuracy for identifying metastatic regional nodes in non-small cell lung cancer based on both PET and CT findings seen on 18F-FDG PET CT. METHODS: Three hundred thirty-nine biopsy-proven NSCLC patients who underwent surgical resection and had a staging 18F-FDG PET CT were enrolled. PET parameters obtained were (1) presence of visual PET positive nodes, (2) SUVmax of nodes (NSUV), (3) ratio of node to aorta SUVmax (N/A ratio) and (4) ratio of node to primary tumour SUVmax (N/T ratio). CT parameters obtained were (1) short-axis diameter and (2) Hounsfield units (HU) of PET-positive nodes. PET and CT parameters were correlated with nodal histopathology to find out the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and overall accuracy. Different PM combining these parameters were devised and the incremental improvement in accuracy was determined. RESULTS: Visual PET positivity showed sensitivity, specificity, PPV, NPV and accuracy of 72.4, 76.1, 30.1, 95.1 and 75.6, respectively. PM2 which combined visual PET positivity, NSUV and HU appears more clinically relevant and showed sensitivity, specificity, PPV, NPV and accuracy of 53.5, 96.5, 68.9, 93.6 and 91.2, respectively. PM6 which combined visual PET positivity, NSUV, N/A ratio and HU showed the maximum PPV (80.0%), specificity (98.3%) and accuracy of (91.9%). CONCLUSION: PM combining parameters like nodal SUVmax, N/A ratio, N/T ratio and HU values have shown to improve the PPV, specificity and overall accuracy of 18FDG PET CT in the preoperative diagnosis of nodal metastases.

Comparison of predicted postoperative forced expiratory volume in the first second (FEV1) using lung perfusion scintigraphy with observed forced expiratory volume in the first second (FEV1) post lung resection.

Lung perfusion scintigraphy is done as a part of preoperative evaluation in lung cancer patients for the prediction of postoperative forced expiratory volume in the first second (FEV1). This study was performed to see the accuracy of prediction of postoperative FEV1 by perfusion scintigraphy for patients undergoing lobectomy/pneumonectomy by comparing it with actual postoperative FEV1 obtained by spirometry 4-6 months after surgery. We retrospectively reviewed 50 surgically resected lung cancer patients who underwent preoperative spirometry, lung perfusion study, and postoperative spirometry. Pearson's correlation coefficient was used to evaluate the relationship between predicted postoperative FEV1 (PPO FEV1) by lung perfusion scintigraphy and postoperative actual FEV1 measured by spirometry. Agreement between the two methods was analyzed with Bland-Altman method. The correlation between the PPO FEV1 and actual postoperative FEV1 was statistically significant (r = 0.847, P = 0.000). The correlation was better for pneumonectomy compared to lobectomy (r = 0.930 [P = 0.000] vs. 0.792 [P = 0.000]). The agreement analysis showed a mean difference of -0.0558 with a standard deviation (SD) of 0.284. The limits of agreement vary over a wide range from --0.625 to 0.513 L (mean ± 2 SD) for the entire group. For pneumonectomy, the mean difference was -0.0121 and SD 0.169 with limits of agreement varying between -0.30 L and 0.30 L. For lobectomy, the mean difference was -0.0826 and SD 0.336 with limits of agreement varying between -0.755 L and 0.590 L. Postoperative FEV1 predicted using lung perfusion scintigraphy shows good correlation with actual postoperative FEV1 and shows reasonably good agreement in patients undergoing pneumonectomy. The limits of agreement appear to be clinically unacceptable in patients undergoing lobectomy, where single-photon emission computed tomography (SPECT) or SPECT/CT techniques may improve prediction.

Prognostic value of metabolic parameters measured by 18F-fluorodeoxyglucose positron emission tomography-computed tomography in surgically resected non-small cell lung cancer patients.

18F-fluorodeoxyglucose positron emission tomography-computed tomography-derived metabolic parameters can play a role in prognostication. We investigated the prognostic value of various metabolic parameters such as maximum standardized uptake value (SUVmax), mean SUV (SUVmean), whole-body metabolic tumor volume (WBMTV), and whole-body total lesion glycolysis (WBTLG) in surgically resected non-small cell lung cancer (NSCLC) patients. We retrospectively reviewed 153 patients with NSCLC who underwent surgical resection. The SUVmax, SUVmean, WBMTV, and WBTLG of the tumor were measured. Continuous PET parameters were stratified by receiver operating characteristic curve analysis. Prognostic factors were estimated using the Kaplan-Meier method and Cox proportional hazards model. The median follow-up was 36.9 months. Fifty-six patients died and 78 patients had recurrence. On univariate analysis, tumor-node-metastasis (TNM) stage; male sex; no adjuvant treatment; and higher SUVmax, SUVmean, WBMTV, and WBTLG were statistically significant and were associated with poor overall survival (OS). TNM stage; no adjuvant treatment; and higher SUVmax, SUV mean, WBMTV, and WBTLG were statistically significant and were associated with poor disease-free survival (DFS). On multivariate analysis, higher WBTLG (hazard ratio [HR] = 3.08, P = 0.007) for DFS and higher WBTLG (HR = 2.70, P = 0.041) and TNM staging (HR = 1.63, P = 0.035) for OS were statistically significant. Whole-body tumor burden assessment with TLG has independent prognostic value in patients with operated lung cancer. Incorporation of TLG into clinical practice can identify patients benefitted from additional therapy.

Prognostic Value of 18F-FDG PET/CT-Metabolic Parameters at Baseline and Interim Assessment in Pediatric Anaplastic Large Cell Lymphoma.

INTRODUCTION: The event-free survival in pediatric anaplastic large cell lymphoma (ALCL) remains at 70% irrespective of the diverse chemotherapy regimens used. There is lack of valid prognostic factors identifying high-risk patients. We investigated the prognostic value of baseline metabolic parameters and interim response on F-FDG PET/CT in pediatric ALCL patients. METHODS: We retrospectively reviewed 40 pediatric ALCL patients with paired F-FDG PET/CT and treated uniformly on vinblastine-based institution protocol. The SUVmax, SUVmean, metabolic tumor volume (MTV), and total lesion glycolysis of the lymphomatous lesion were measured. Continuous PET parameters were stratified by their median values. Deauville scoring system was used to assess response to chemotherapy in the interim scan. Prognostic factors for overall survival (OS) and disease-free survival (DFS) were estimated using the Kaplan-Meier method, log-rank test, and Cox proportional hazards model. RESULTS: At median follow-up of 52 months, 13 patients died and 13 had recurrence. On univariate analysis, higher whole-body MTV (WBMTV) and partial response on interim scan were statistically associated with OS. High-risk features, WBMTV, and partial response were statistically associated with DFS. On multivariate analysis combining baseline characteristics and interim response, interim response (hazard ratio, 3.56; P = 0.034) was statistically significant for OS. Multivariate analysis for DFS using only baseline characteristics revealed WBMTV as statistically significant (hazard ratio, 4.08; P = 0.035), but none of the parameters was statistically significant when baseline characteristics and interim response were evaluated together. CONCLUSIONS: Whole-body tumor burden assessment with MTV and interim response may help to identify high-risk patients who might get benefitted from intensive therapy.

Incidental Detection of Pleomorphic Sarcoma on 68Ga-PSMA PET/CT in a Patient With Prostate Cancer.

Ga prostate-specific membrane antigen (PSMA) PET/CT is used in the staging, evaluation of biochemical recurrence, and response assessment of patients with prostate cancer. In addition to the PSMA-expressing prostate cancer cells, Ga-PSMA binds to the neovasculaature of various other solid tumors and benign lesions. We report a case of a 72-year-old man with recently diagnosed adenocarcinoma of prostate, incidentally found to have pleomorphic sarcoma on the staging Ga-PSMA PET/CT.

Progressive Hydrocephalus Due to Ventriculoperitoneal Shunt Infection: Detection With FDG PET CT.

Ventriculoperitoneal shunt malfunction is common in patients after shunt surgery. Imaging is done to reveal the underlying cause and confirm the diagnosis. Shunt infection is one of the common causes of shunt malfunction. FDG PET CT is an accepted infection imaging tool and can be used to diagnose shunt infection accurately in a patient with high clinical suspicion.

Lung Masses of Unusual Histologies Mimicking Malignancy: Flurodeoxyglucose Positron Emission Tomography-Computed Tomography Appearance.

18F flurodeoxyglucose positron emission tomography-computed tomography (18F FDG PET-CT) is widely used in the evaluation of patients with lung mass suspicious for malignancy. In addition to malignancy, a variety of benign neoplasms and inflammatory lesions can arise in the lungs, many of which show increased FDG concentration, thereby mimicking malignancy. Awareness of the common mimics of lung cancer and a thorough understanding of their key imaging characteristics on CT as well as FDG PET is helpful in narrowing the differential diagnosis, eventually leading to appropriate therapy. In this article, we enlist these mimics and discuss their metabolic and morphologic characteristics and provide a pathophysiological basis for their FDG uptake.