ABSTRACT
Background: Prostate-specific membrane antigen (PSMA) positron emission tomography/computerised tomography (PET/CT) is increasingly being utilised in the diagnostic pathway for prostate cancer (PCa). Recent publications have suggested that this might help identify those who can avoid biopsy. Objective: The primary objective of this study was to determine whether PET magnetic resonance imaging (MRI) fusion could negate the need to biopsy prior to prostatectomy in a selected population of men. Design setting and participant: Multiparametric MRI (mpMRI) for PCa is our standard of care prior to prostate biopsy. Biopsy-naïve men with one or more Prostate Imaging Reporting and Data System (PI-RADS) 4 or 5 lesions ≥10 mm on mpMRI were invited to undergo PSMA PET/CT prior to biopsy. Following ethics approval, 60 men were recruited between September 2020 and March 2021. The key exclusion criteria included a previous history of PCa and previous prostate surgery or biopsy. Outcome measurements and statistical analysis: A positive PET MRI fusion scan was defined as "consistent with" as per the Memorial Sloan Kettering Cancer Center lexicon of certainty, and concordance with biopsy results was analysed. Clinically significant PCa (csPCa) was defined as grade group (GG) ≥2 on pathology. A chi-square analysis was performed with statistical significance defined at p < 0.05. Results and limitations: A total of 71 mpMRI lesions were positive on 61 (86%) PET MRI fusion scans. Fifty-nine of 61 lesions biopsied confirmed csPCa in 54 (92%). Of five of 59 lesions for which either biopsy was negative or low-grade cancer was found, three had rebiopsy of which two were confirmed to have csPCa corroborating with PET MRI fusion and one was reconfirmed to have GG1 only. For the remaining two, both had another lesion elsewhere in the gland confirming csPCa, and hence rebiopsy was not performed. Ultimately, 56 of 59 (95%) lesions with a positive PET MRI fusion scan were confirmed to have csPCa. All GG ≥3 cancers had a positive PET MRI fusion scan. Conclusions: This prospective study of PET MRI fusion assessment of men with PI-RADS 4 or 5 lesion ≥10 mm on mpMRI confirms that the majority of men (95%) with a positive PET MRI fusion scan will have csPCa. This supports recently published retrospective data suggesting that selected men might avoid prostate biopsy prior to radical prostatectomy. Patient summary: In this research, we have confirmed that prostate-specific membrane antigen positron emission tomography/computerised tomography in combination with magnetic resonance imaging could have an important role in enabling a diagnosis of prostate cancer. Using the combination of these scans, we could confidently predict the presence of aggressive prostate cancer in some men for which treatment is warranted. This means that there are some men who could possibility proceed directly to having prostate cancer surgery without the need for a confirmatory prostate biopsy.
ABSTRACT
UNLABELLED: INTRODUCTION (PURPOSE OF THE STUDY): The objective of this study was to assess whether dual-time-point (18)F-fluoro-2-deoxyglucose ((18)F-FDG)-PET/CT imaging improved the evaluation of suspected malignancy and if there was any resulting change in management. METHODS: A total of 53 patients with suspected malignancy were investigated by performing two static acquisitions started at mean times t = 64 and t = 155 min after the tracer injection. The total number of malignant lesions was 133 and the total number of benign lesions was 61. Visual and semiquantitative analysis was performed on both the early and delayed images. RESULTS: Overall, there was a significant improvement (P < 0.001) in the sensitivity of delayed imaging (94%) compared with early imaging (77%) in detecting malignant lesions, without a reduction in specificity. In 10 patients, 13 malignant lesions were undetected on early imaging alone but detected on delayed imaging. In seven patients, 10 malignant lesions were incorrectly classified as 'likely benign' on early imaging but correctly reported as 'likely malignant' on delayed imaging. Management was altered in 2 out of 17 patients. Overall, delayed imaging altered management in 2 out of 53 studied patients. Dual-time-point (18)FDG-PET/CT imaging was useful in differentiating malignant from benign intra-abdominal lesions but did not improve the evaluation of pulmonary lesions. CONCLUSIONS: (18)F-FDG-PET/CT imaging should be performed as late as reasonably possible after tracer administration in order to increase tumour-to-background contrast and thereby improve the sensitivity of demonstrating additional sites of disease. Dual-time-point (18)FDG-PET/CT may be of benefit in the evaluation of intra-abdominal lesions but does not improve the overall evaluation of pulmonary lesions.