Dual-Time-Point FDG Uptake Correlates with Prognostic Factors of Invasive Breast Cancer: Clinical Usefulness of Early Delayed Scanning

Does FDG PETCT have a predictive value for neoadjuvant chemotherapy response in nonmetastatic breast cancer?

BACKGROUND

A pathological complete response (pCR) rate after neoadjuvant chemotherapy (NAC) is important for the prognosis of early-stage breast cancer. The prediction of an NAC response plays a key role in managing neoadjuvant treatment.

AIMS

The aim of this study is to investigate the predictive value of the baseline PETCT FDG (F-18 fluoro-deoxy-glucose (FDG) positron emission tomography/computed tomography) SUVmax (the maximum standardized uptake value) for pCR after NAC in early-stage breast cancer.

METHODS

The patients who performed PETCT before NAC were included in this retrospective study. The basal PETCT SUVmax values were divided into two categories based on the cutoff points of ≥ 8.77 or < 8.77, namely the low SUV max group and the high SUV max group. These two groups were compared according to the general characteristics. The impact of the PETCT SUVmax values on pCR was determined with logistic regression analyses.

RESULTS

One hundred forty-eight patients who performed PETCT before NAC were included in this retrospective study. Eighty-one patients were in the low SUV max group and 67 patients were in the high SUVmax group. The pCR trended toward a higher rate in the high SUVmax group than in low SUVmax group but it was not statistically significant (p = 0.052). The baseline PETCT SUVmax value was an independent predictive factor for pCR. (p = 0.025).

CONCLUSION

PETCT SUVmax may be a factor for the predicting complete response to neoadjuvant treatment in early-stage breast cancer.

Detection of Hepatic Metastasis from Early Delayed Images of Modified Dual-Time-Point F-18 FDG PET/CT Images in a Patient with Breast Cancer

We present a rare case of focal F-18-2-fluoro-2-deoxyglucose (FDG) uptake in the liver observed during a modified dual-time-point F-18 FDG positron emission tomography (PET)/computed tomography (CT), so-called early delayed scanning, in a 53-year-old woman diagnosed with breast cancer. This metastatic lesion was revealed in 80 min delayed images after FDG injection, but not in the usual one-hour images after injection. Modified dual-time-point F-18 FDG PET/CT is convenient because compared to the 2 h delayed images of dual-time-point PET/CT, it has a shorter scanning time and avoids additional radiation exposure.

Diagnostic Superiority of Dual-Time Point [18F]FDG PET/CT to Differentiate Malignant from Benign Soft Tissue Tumors

[18F]FDG PET/CT is used in the workup of indeterminate soft tissue tumors (STTs) but lacks accuracy in the detection of malignant STTs. The aim of this study is to evaluate whether dual-time point [18F]FDG PET/CT imaging (DTPI) can be useful in this indication. In this prospective study, [18F]FDG PET/CT imaging was performed 1 h (t1) and 3 h (t2) after injection. Tumor uptake (SUVmax) was calculated at each time point to define a retention index (RI) corresponding to the variation between t1 and t2 (%). Sixty-eight patients were included, representing 20 benign and 48 malignant tumors (including 40 sarcomas). The RI was significantly higher in malignant STTs than in benign STTs (median: +21.8% vs. -2%, p < 0.001). An RI of >14.3% predicted STT malignancy with a specificity (Sp) of 90% and a sensitivity (Se) of 69%. An SUVmaxt1 of >4.5 was less accurate with an Sp of 80% and an Se of 60%. In a subgroup of tumors with at least mild [18F]FDG uptake (SUVmax ≥ 3; n = 46), the RI significantly outperformed the diagnostic accuracy of SUVmax (AUC: 0.88 vs. 0.68, p = 0.01). DTPI identifies malignant STT tumors with high specificity and outperforms the diagnostic accuracy of standard PET/CT.

Feasibility of [18F]FDG PET/MRI with Early-Delayed and Extended PET as One-Stop Imaging for Staging and Predicting Metastasis in Rectal Cancer

BACKGROUND

We aimed to evaluate the diagnostic accuracy of [18F]FDG PET/MRI for preoperative staging and usefulness of the detection of extramural vascular invasion (EMVI) for predicting metastasis in rectal cancer.

METHODS

Twenty-three patients underwent pretreatment [18F]FDG PET/MRI including early-delayed and extended PET and dedicated pelvic MRI without using anticonvulsant or contrast agents. Seven patients received preoperative treatment and all subsequently underwent surgery. Clinical cancer stages were evaluated using postoperative histopathology as a reference. PET/MR-defined EMVI (pmrEMVI) and pathological (p) TN stages were correlated with disease progression for a maximum of 2 years.

RESULTS

Of 16 patients without preoperative treatment, 10 had pT3,4 tumors, 7 had pN1-3 lymph nodes, and 5 had synchronous metastases (SM; liver, lung, inguinal node). The sensitivity, specificity, and accuracy of PET/MRI were 90%, 67%, and 81% for T staging (T1,2 vs. T3,4), and 89%, 100%, and 94% for N staging (N0 vs. N1-3), respectively. Patient-based accuracy for SM staging was 100% (4/4). Of 23 patients, 6 were positive for pmrEMVI and 4 had metachronous metastases or local recurrence (MM; pelvic node, brain, lung, skin) during the follow-up periods. Five of the 6 pmrEMVI-positive patients had SM and/or MM (odds ratio=37.5). Among pT, pN, and pmrEMVI, pmrEMVI-positivity was the only significant predictor for poorer progression-free survival (p < 0.05).

CONCLUSIONS

[18F]FDG PET/MRI according to our suggested protocol is a one-stop, non-contrast, and valid diagnostic method for rectal cancer staging, and pmrEMVI can be used as an imaging biomarker for predicting metastases.