Initial metabolic tumor volume measured by 18F-FDG PET/CT can predict the outcome of osteosarcoma of the extremities

Large cell neuroendocrine carcinoma of the lung: CT and FDG PET findings

PURPOSE

To evaluate the CT and (18)fluorine FDG PET findings of large cell neuroendocrine carcinomas (LCNECs) of the lung and to evaluate whether CT and FDG PET findings can help predict the clinical outcome.

MATERIAL AND METHODS

Thirty-one patients (Male:Female=29:2; mean age, 69 years) who underwent surgical resection of an LCNEC of the lung were included in this retrospective study. The tumours were assessed with respect to morphologic characteristics and the maximum standardised uptake value (SUVmax) on pre-operative CT and FDG PET. For patients undergoing curative resection (n=26), disease-free survival was evaluated using the Kaplan-Meier test. The prognostic significance was assessed using a multivariate Cox proportional hazards regression analysis.

RESULTS

The mean tumour diameter was 3.8 ± 2.1cm. Eight tumours (25.8%) were located centrally in the lung, and 23 (74.2%) were located peripherally. The margins were lobulated in 29 patients (93.5%) and well defined in 20 (64.5%). The mean SUVmax was 9.0 ± 3.8. The five-year disease-free survival rate was 46.3%. The shorter disease-free survival was related to the TNM stage greater than stage I, no lobulated margin of a tumour, a SUVmax >12.9 of a tumour, a long diameter >5.6 cm of a tumour, or female gender (P=0.115, P=0.134, P=0.056, P=0.168, P=0.113, respectively). The multivariate analysis indicated that a long diameter >5.6 cm (hazard ratio, 9.265; 90% confidence interval (CI), 1.996-42.992; P=0.017), female gender (hazard ratio, 5.579; 90% CI, 1.398-22.264; P=0.041), no lobulated margin (hazard ratio, 9.955; 90% CI, 1.433-69.136; P=0.051), and SUVmax >12.9 (hazard ratio, 4.062; 90% CI, 1.235-13.368; P=0.053) were independent predictors of shorter disease-free survival.

CONCLUSIONS

LCNECs of the lung more commonly occurred peripherally and exhibited well-defined and lobulated margins on CT. The mean SUVmax was consistent with malignant tumours. Female gender, a larger tumour diameter, no lobulated margin, and higher SUVmax were poor prognostic factors.

PET Imaging in Sarcoma

PET imaging has been evaluated in five areas of sarcoma diagnosis and treatment: biopsy guidance, therapeutic monitoring, tumor detection and grading, tumor staging, and prognostication. Current evidence does not include any cost-benefit analysis showing a decreased number of invasive procedures from false-positive results. There is overlap from more conventional imaging and PET imaging without obvious added benefit from information gained from PET/computed tomography scanning. Use as a routine test in patients with sarcoma cannot be recommended. Use in specific histologic subtypes with differing patterns of metastasis or in monitoring those cases undergoing neoadjuvant chemotherapy needs further study before PET/computed tomography becomes standard of care for patients with sarcoma.

Value of FDG PET/CT in Patient Management and Outcome of Skeletal and Soft Tissue Sarcomas

Fluorodeoxyglucose (FDG)-PET/computed tomography (CT) has been increasingly used in bone and soft tissue sarcomas and provides advantages in the initial tumor staging, tumor grading, therapy assessment, and recurrence detection. FDG-PET/CT metabolic parameters are reliable predictors of survival in sarcomas and could be implemented in risk stratification models along with other prognostic factors in these patients.

A semi-automated technique determining the liver standardized uptake value reference for tumor delineation in FDG PET-CT

BACKGROUND

18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)-computed tomography (CT) has been an essential modality in oncology. We propose a semi-automated algorithm to objectively determine liver standardized uptake value (SUV), which is used as a threshold for tumor delineation.

METHODS

A large spherical volume of interest (VOI) was placed manually to roughly enclose the right lobe (RL) of the liver. For each voxel in this VOI, a coefficient of variation of voxel values (CVv) was calculated for neighboring voxels within a radius of d/2. The voxel with the minimum CVv was then selected, where a 30-mm spherical VOI was placed at that voxel in accordance with PERCIST criteria. Two nuclear medicine physicians independently defined 30-mm VOIs manually on 124 studies in 62 patients to generate the standard values, against which the results from the new method were compared.

RESULTS

The semi-automated method was successful in determining the liver SUV that was consistent between the two physicians in all the studies (d = 80 mm). The liver SUV threshold (mean +3 SD within 30-mm VOI) determined by the new semi-automated method (3.12±0.61) was not statistically different from those determined by the manual method (Physician-1: 3.14±0.58, Physician-2: 3.15±0.58). The semi-automated method produced tumor volumes that were not statistically different from those by experts' manual operation. Furthermore, the volume change in the two sequential studies had no statistical difference between semi-automated and manual methods.

CONCLUSIONS

Our semi-automated method could define the liver SUV robustly as the threshold value used for tumor volume measurements according to PERCIST. The method could avoid possible subjective bias of manual liver VOI placement and is thus expected to improve clinical performance of volume-based parameters for prediction of cancer treatment response.

Early response monitoring to neoadjuvant chemotherapy in osteosarcoma using sequential ¹⁸F-FDG PET/CT and MRI

PURPOSE

We evaluated the potential of sequential fluorine-18 fluorodeoxyglucose ((18) F-FDG) positron emission tomography (PET)/computed tomography (CT) and MRI (PET/MRI) after one cycle of neoadjuvant chemotherapy to predict a poor histologic response in osteosarcoma.

METHODS

A prospective study was conducted on 30 patients with osteosarcoma treated with two cycles of neoadjuvant chemotherapy and surgery. All patients underwent PET/MRI before, after one cycle, and after the completion of neoadjuvant chemotherapy, respectively. Imaging parameters [maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and tumor volume based on magnetic resonance (MR) images (MRV)] and their % changes were calculated on each PET/MRI data set, and histological responses were evaluated on the postsurgical specimen.

RESULTS

A total of 17 patients (57%) exhibited a poor histologic response after two cycles of chemotherapy. Unlike the little volumetric change in MRI, PET parameters significantly decreased after one and two cycles of chemotherapy, respectively. After one cycle of chemotherapy, SUVmax, MTV, and TLG predicted the poor responders. Among these parameters, either MTV ≥ 47 mL or TLG ≥ 190 g after one cycle of chemotherapy was significantly associated with a poor histologic response on multivariate logistic regression analysis (OR 8.98, p = 0.039). The sensitivity, specificity, and accuracy of these parameters were 71%, 85% and 77%; and 71%, 85% and 77 %, respectively.

CONCLUSION

The histologic response to neoadjuvant chemotherapy in osteosarcoma can be predicted accurately by FDG PET after one course of chemotherapy. Among PET parameters, MTV and TLG were independent predictors of the histologic response.