Diagnostic and Interventional Radiology
Abdominal Imaging - Original Article

Natural history of small index lesions suspicious for prostate cancer on multiparametric MRI: recommendations for interval imaging follow-up

1.

Center for Urologic Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.

2.

Molecular Imaging Program, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA

3.

Urologic Oncology Branc, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA

4.

Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA

5.

Center for Interventional Oncology, National Cancer Institute & Clinical Center, National Institutes of Health, Bethesda, Maryland, USA

Diagn Interv Radiol 2014; 20: 293-298
DOI: 10.5152/dir.2014.13319
Read: 549 Downloads: 140 Published: 03 September 2019

Abstract

PURPOSE

We aimed to determine the natural history of small index lesions identified on multiparametric-magnetic resonance imaging (MP-MRI) of the prostate by evaluating lesion-specific pathology and growth on serial MP-MRI.

 

MATERIALS AND METHODS

We performed a retrospective review of 153 patients who underwent a minimum of two MP-MRI sessions, on an institutional review board-approved protocol. Index lesion is defined as the lesion(s) with the highest cancer suspicion score based on initial MP-MRI of a patient, irrespective of size. Two study cohorts were identified: (1) patients with no index lesion or index lesion(s) ≤7 mm and (2) a subset with no index lesion or index lesion(s) ≤5 mm. Pathological analysis of the index lesions was performed following magnetic resonance/ultrasound fusion-guided biopsy. Growth rate of the lesions was calculated based on MP-MRI follow-up.

 

RESULTS

Patients with small index lesions measuring ≤7 mm (n=42) or a subset with lesions ≤5 mm (n=20) demonstrated either benign findings (86.2% and 87.5%, respectively) or low grade Gleason 6 prostate cancer (13.8% and 12.5%, respectively) on lesion-specific targeted biopsies. These lesions demonstrated no significant change in size (P = 0.93 and P = 0.36) over a mean imaging period of 2.31±1.56 years and 2.40±1.77 years for ≤7 mm and ≤5 mm index lesion thresholds, respectively. These findings held true on subset analyses of patients who had a minimum of two-year interval follow-up with MP-MRI.

 

CONCLUSION

Small index lesions of the prostate are pathologically benign lesions or occasionally low-grade cancers. Slow growth rate of these small index lesions on serial MP-MRI suggests a surveillance interval of at least two years without significant change.

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