RESUMO
Purpose: This prospective study aimed to evaluate the difference between 99mTc-PSMA single-photon emission computed tomography (SPECT)/CT and multiparametric magnetic resonance imaging (mpMRI) in the detection of primary prostate cancer (PCa). Materials and methods: Fifty-six men with suspected PCa between October 2019 and November 2022 were prospectively enrolled in this study. The median age of the patients was 70 years (range, 29-87 years). Patients were divided into high-(Gleason score>7, n=31), medium- (Gleason score=7, n=6) and low-risk groups (Gleason score < 7, n=6). All patients underwent 99mTc-PSMA SPECT/CT and mpMRI at an average interval of 3 days (range, 1-7 days). The maximum standardized uptake value (SUVmax), the minimum apparent diffusion coefficient (ADCmin), and their ratio (SUVmax/ADCmin) were used as imaging parameters to distinguish benign from malignant prostatic lesions. Results: Of the 56 patients, 12 were pathologically diagnosed with a benign disease, and 44 were diagnosed with PCa. 99mTc-PSMA SPECT/CT and mpMRI showed no significant difference in the detection of primary PCa (kappa =0.401, P=0.002), with sensitivities of 97.7% (43/44) and 90.9% (40/44), specificities of 75.0% (9/12) and 75.0% (9/12), and AUC of 97.4% and 95.1%, respectively. The AUC of SUVmax/ADCmin was better than those of SUVmax or ADCmin alone. When SUVmax/ADCmin in the prostatic lesion was >7.0×103, the lesion was more likely to be malignant. When SUVmax/ADCmin in the prostatic lesion is >27.0×103, the PCa patient may have lymph node and bone metastases. SUVmax was positively correlated with the Gleason score (r=0.61, P=0.008), whereas ADCmin was negatively correlated with the Gleason score (r=-0.35, P=0.023). SUVmax/ADCmin was positively correlated with the Gleason score (r=0.59, P=0.023). SUVmax/ADCmin was the main predictor of the high-risk group, with an optimal cut-off value of 15.0×103. Conclusions: The combination of 99mTc-PSMA SPECT/CT and mpMRI can improve the diagnostic efficacy for PCa compared with either modality alone; SUVmax/ADCmin is a valuable differential diagnostic imaging parameter.
RESUMO
The most common site of metastasis of prostate cancer (PCa) is bone. Skeletal-related events can increase the risk of death in patients with PCa by 28%. Due to the low detection rate of lesions in patients with low prostate-specific antigen (PSA) levels, the value of 99mTc methylene diphosphonate (99mTc-MDP) bone scintigraphy is limited. Prostate-specific membrane antigen (PSMA) is a small molecular probe that can efficiently and specifically detect PCa lesions. This prospective study aimed to evaluate the difference between 99mTc-PSMA single-photon emission computed tomography (SPECT)/CT and 99mTc-MDP SPECT/CT in the detection of bone metastasis in PCa. A total of 74 men with pathologically confirmed PCa from October 2019 to November 2021 were prospectively enrolled in this study. The median age was 70 (range, 55-87) years. All patients underwent both 99mTc-PSMA SPECT/CT and 99mTc-MDP SPECT/CT at an average interval of 12.1 (range, 1-14) days. The detected imaging-positive bone lesions were scored as "typical metastasis" or "equivocal metastasis" by a standard reporting schema. Subsequent therapy modality details were observed through follow-up. Twenty-five of the 74 patients were diagnosed with bone metastases. 99mTc-PSMA SPECT/CT and 99mTc-MDP SPECT/CT detected 20 and 18 bone metastases, with sensitivities of 80.0% (20/25) and 72.0% (18/25), specificities of 100.0% (49/49) and 81.3% (40/49), and AUCs of 88.0% and 84.9%, respectively. There was a significant difference in the AUC between the two imaging methods (P < 0.001). In an analysis of the number of bone metastasis lesions, the proportion of "typical metastasis" versus "equivocal metastasis" detected by the two imaging methods was 26.3:1 (PSMA) and 2.9:1 (MDP), and the difference was statistically significant (P = 0.005). There was a significant difference in the detection of bone metastatic lesions by 99mTc-PSMA and 99mTc-MDP when the maximum diameter of the lesions was ≤ 0.6 cm (P < 0.05). The optimal cut-off value for PSA was 2.635 ng/mL (PSMA) and 15.275 ng/mL (MDP). 99mTc-PSMA SPECT/CT led to a change in management to a more individualized therapy modality for 11 of 74 men (14.9%). 99mTc-PSMA SPECT/CT was superior to 99mTc-MDP SPECT/CT in the detection of bone metastases in PCa, especially for small lesions and in patients with low PSA levels, and demonstrated an additional benefit of providing information on extraskeletal metastases. With regard to therapy, 99mTc-PSMA scans might have utility in improving the subsequent therapy modality.
