Role of F-18 FDG PET/CT in Predicting Response to Neoadjuvant Chemotherapy in Invasive Ductal Breast Cancer

Objective:

The role of baseline and post-treatment standardized uptake value (SUV_max) values in predicting pathological response in patients with breast cancer after neoadjuvant chemotherapy (NAC).

Materials and Methods:

Thirty patients with invasive ductal breast cancer were included in this retrospective study. F-18 fluorodeoxyglucose (FDG) positron emission tomography/computerized tomography (PET/CT) examinations were performed before and after NAC. Pretreatment SUV_max (SUV_max I), post-treatment SUV_max (SUV_max II) and ΔSUV_max values of primary breast cancer were obtained. Breast tumor pathology preparations were examined for the evaluation of tumor response according to the Miller and Payne classification. Patients were grouped as responding to treatment (pCR) and unresponsive to treatment (nonpCR). In all analyses, p<0.05 was considered statistically significant.

Results:

The mean age of the 30 patients included in the study was 51.2±11.98 years. In the study-defined grouping, 13 patients (43.3%) were nonresponders and 17 patients (56.7%) were responders. ΔSUV_max was significantly greater in the responders group compared to the nonresponders group, while SUV_max II was lower (p = 0.001 and p = 0.004, respectively). There was no significant difference between the responders and nonresponders in terms of age, tumor diameter, and SUV_max I values. Multivariate logistic regression analysis showed ΔSUV_max to be the only independent predictive factor for pCR.

Conclusion:

F-18 FDG PET/CT was an effective method in evaluating the treatment response after NAC in breast cancer, and ΔSUV_max and post-treatment SUV_max can be used to predict the response of the primary tumor to treatment.

Precise characterization of a solitary pulmonary nodule using tumor shadow disappearance rate-corrected F-18 FDG PET and enhanced CT

We aimed to characterize solitary pulmonary nodule (SPN) using imaging parameters for F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) or enhanced CT corrected by tumor shadow disappearance rate (TDR) to reflect the tissue density.We enrolled 51 patients with an SPN who underwent PET/CT and chest CT with enhancement. The FDG uptake of SPN was evaluated using maximum standardized uptake value (SUVmax) on PET/CT. The mean Hounsfield unit (HU) for each SPN was evaluated over the region of interest on nonenhanced and enhanced CT images. The change in mean HU (HUpeak-pre) was quantified by subtracting the mean HU of the preenhanced CT from that of the post-enhanced CT. TDR was defined as the ratio of the tumor area, which disappears at a mediastinal window, to the tumor area of the lung window. We investigated which parameters (SUVmax or HUpeak-pre) could contribute to the characterization of SPN classified by TDR value and whether diagnostic performance could be improved using TDR-corrected imaging parameters.For SPN with higher tissue density (TDR <42%, n = 22), high value of SUVmax (≥3.1) was a significant factor to predict malignancy (P = .006). High value of HUpeak-pre (≥38) was a significant factor to characterize SPN (P = .002) with lower tissue density (TDR ≥42%, n = 29). The combined approach using TDR-corrected parameters had better predictive performance to characterize SPN than SUVmax only (P = .031).Applying imaging parameters such as SUVmax or HUpeak-pre in consideration of tissue density calculated with TDR could contribute to accurate characterization of SPN.

Reliability of Quantitative 18F-FDG PET/CT Imaging Biomarkers for Classifying Early Response to Chemoradiotherapy in Patients With Locally Advanced Non-Small Cell Lung Cancer

PURPOSE OF THE REPORT

We evaluated the reliability of 18F-FDG PET imaging biomarkers to classify early response status across observers, scanners, and reconstruction algorithms in support of biologically adaptive radiation therapy for locally advanced non-small cell lung cancer.

PATIENTS AND METHODS

Thirty-one patients with unresectable locally advanced non-small cell lung cancer were prospectively enrolled on a phase 2 trial (NCT02773238) and underwent 18F-FDG PET on GE Discovery STE (DSTE) or GE Discovery MI (DMI) PET/CT systems at baseline and during the third week external beam radiation therapy regimens. All PET scans were reconstructed using OSEM; GE-DMI scans were also reconstructed with BSREM-TOF (block sequential regularized expectation maximization reconstruction algorithm incorporating time of flight). Primary tumors were contoured by 3 observers using semiautomatic gradient-based segmentation. SUVmax, SUVmean, SUVpeak, MTV (metabolic tumor volume), and total lesion glycolysis were correlated with midtherapy multidisciplinary clinical response assessment. Dice similarity of contours and response classification areas under the curve were evaluated across observers, scanners, and reconstruction algorithms. LASSO logistic regression models were trained on DSTE PET patient data and independently tested on DMI PET patient data.

RESULTS

Interobserver variability of PET contours was low for both OSEM and BSREM-TOF reconstructions; intraobserver variability between reconstructions was slightly higher. ΔSUVpeak was the most robust response predictor across observers and image reconstructions. LASSO models consistently selected ΔSUVpeak and ΔMTV as response predictors. Response classification models achieved high cross-validated performance on the DSTE cohort and more variable testing performance on the DMI cohort.

CONCLUSIONS

The variability FDG PET lesion contours and imaging biomarkers was relatively low across observers, scanners, and reconstructions. Objective midtreatment PET response assessment may lead to improved precision of biologically adaptive radiation therapy.

Assessment of change in glucose metabolism in white matter of amyloid-positive patients with Alzheimer disease using F-18 FDG PET

In Alzheimer disease (AD), neuroinflammation is an important process related to the deposition of beta-amyloid plaques and the activation of microglia. The inflammatory process can occur in both the gray matter and the white matter. We evaluated glucose metabolism of the white matter in AD patients and compared the value with cognitive parameters of the patients.Eighteen AD patients and 18 healthy subjects underwent F-18 fluorodeoxyglucose (FDG) and F-18 florbetaben positron emission tomography (PET). After segmentation of the white matter in both PET images, the specific binding ratio (SBR) of the global and regional cerebral white matter was checked. We evaluated the differences in SBR of the global and regional white matter between AD patients and healthy subjects. Then, we assessed the correlation between SBR and cognitive parameters in AD patients.In F-18 FDG PET images, the global white matter SBR was significantly higher in AD patients than in healthy subjects. In the regional analysis, the white matter SBR was significantly higher for the frontal, temporal, and parietal areas in AD patients. In the correlation analysis with F-18 FDG PET, SBR was significantly correlated with the Global Deterioration Scale, Mini-Mental State Examination scores, and amyloid deposition.Glucose metabolism of the white matter was significantly higher in AD patients than in healthy subjects and it was related to the scores of cognitive parameters. We suggest that F-18 FDG PET, like 18-kDa translocator protein PET, could be used as an indicator of neuroinflammation; however, further research is needed for a direct comparison between the 2 tests.

Extracranial bone metastases from recurrent anaplastic astrocytoma on FDG PET/CT: A case report a care-compliant article

OBJECTIVE

Extracranial bone metastases from astrocytoma are rare and frequently detected as part of multiorgan metastases. It is extremely rare for astrocytoma to have extracranial bone metastases alone. The importance of whole-body fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) imaging in evaluating extracranial metastasis (ECMs) has not been described effectively due to the rarity of this event. The purpose of our case report is to emphasize the role of FDG PET/CT in the assessment of tumor recurrence and extracranial bone metastases from anaplastic astrocytoma.

METHODS AND MATERIALS

A 25-year-old woman was firstly admitted with a 4-month history of progressive blurred vision, and 2-month history of intermittent headache. Presurgical MRI imaging revealed a large mass in the left trigone of lateral ventricle. Subsequently, she underwent tumor resection, radiotherapy and chemotherapy. A final pathological diagnosis of anaplastic astrocytoma (WHO III) was made. Nearly 12 months after the surgery, the follow-up brain MR imaging revealed a contrast-enhanced lesion in the site of operative region. Whole-body FDG PET/CT imaging was performed to evaluate the situation.

RESULTS

Postoperative brain FDG PET/CT showed an abnormal focal FDG uptake corresponding to the contrast-enhanced lesion in the operative area, suggesting a tumor recurrence. Whole-body FDG PET/CT also showed multiple FDG-avid osteosclerotic lesions in the body. It was highly suggestive of extracranial bone metastases. A subsequent open bone biopsy of FDG-avid lesion in right iliac crest was performed. Histopathological and immunohistochemical findings indicated characteristic of glioma. The patient died 1 month later, nearly 13 months after the initial diagnosis.

CONCLUSIONS

ECMs from anaplastic astrocytoma are extremely rare but they do occur. Whole-body FDG PET/CT imaging with inclusion of brain was valuable in differentiating tumor recurrence from radiation necrosis and in detecting uncommon extracranial bone metastases from anaplastic astrocytoma, which were closely related to prognosis of this disease.