F-18 fluorocholine positron emission tomography- computed tomography in initial staging and recurrence evaluation of prostate carcinoma: A prospective comparative study with diffusion-weighted magnetic resonance imaging and whole-body skeletal scintigraphy

Abstract

Prostate cancer (PCa) is one of the major causes of death due to cancer in men. Conventional imaging modalities such as magnetic resonance imaging (MRI) provide locoregional status, but fall short in identifying distant metastasis. C-11 choline F-18 fluorocholine (F-18 FCH) has been shown to be useful in imaging of PCa. The present prospective study evaluates and compares the role of F-18 FCH positron emission tomography-computed tomography (PET-CT) with locoregional MRI and whole-body bone scintigraphy in PCa patients for initial staging and recurrence evaluation. This study included a total of 50 patients. Tc-99m skeletal scintigraphy, F-18 FCH PET-CT, and diffusion-weighted MRI of the pelvic region were performed within a span of 2-3 weeks of each other, in random order. For the primary site, core biopsy findings of the lesion were considered as gold standard. The kappa test was used to measure agreement between bone scintigraphy, F-18 FCH, and MRI. For comparing Tc-99m bone scintigraphy, F-18 FCH, and MRI, McNemar's test was applied. F-18 FCH PET-CT and MRI were able to detect primary lesion in all initial staging patients. The sensitivity and specificity of F-18 FCH PET-CT versus MRI were found to be 92.8% versus 89.2% and 100 versus 80%, respectively, for the recurrence at the primary site. A total of 55 bony lesions at distant sites were detected on F-18 FCH PET-CT in comparison to 43 bone lesions on whole-body bone scintigraphy. F-18 FCH PET/CT also detected additional lung lesions in 2 patients and abdominal lymph nodes in 12 patients. F-18 FCH PET-CT could detect primary lesions, local metastasis, bone metastasis, and distant metastasis in a single study and is also a useful modality in recurrence evaluation in PCa patients.

Keywords: F-18 fluorocholine; Tc-99m MDP bone scans; magnetic resonance imaging; positron emission tomography–computed tomography; prostate cancer; prostate-specific antigen.

Figure 1

Whole-body F-18 fluorocholine positron emission tomography–computed tomography (a-d), regional magnetic resonance imaging (e and f), and bone scan (g) for initial staging of a 64-year-old man with prostate-specific antigen of 8.16 ng/ml. Maximum intensity projection image (a) shows foci of abnormal uptake in thoracic and pelvic regions. The corresponding fused transaxial positron emission tomography–computed tomography image (b) shows intense radiotracer uptake (maximum standardized uptake value 11.2) in the nodular lesion in right peripheral zone of prostate gland. Moderate F-18 fluorocholine is also noted in right internal iliac and hilar lymph nodes (c and d respectively). CE-magnetic resonance imaging image (e) shows early enhancement focus in the right peripheral zone and diffusion restriction in the same region on DWI-magnetic resonance imaging image (f). Tc-99 m methylene-diphosphonate whole-body bone scan (g) does not show any metastasis. The mild focal uptake on MIP image on the right side of the head near midline corresponded to choroid plexus in transaxial images and is physiological uptake. Radical prostatectomy specimen on histologic evaluation showed adenocarcinoma in the right lobe while left lobe was free of tumor

Figure 2

Whole-body F-18 fluorocholine positron emission tomography–computed tomography (a-d), regional magnetic resonance imaging (e and f) and bone scan (g) imaging done for recurrence evaluation, in a 75 years old man on hormonal therapy with rising prostate-specific antigen (30.23 ng/mL). Abnormal radiotracer uptake is seen in abdominal and pelvic regions on MIP image (a) which on fused transaxial positron emission tomography–computed tomography (b) localizes to a lesion in the left peripheral zone at the base of prostate gland (maximum standardized uptake value 7.3) at 5'O position. Intense tracer uptake (maximum standardized uptake value 6.1) is observed in right posterolateral wall of urinary bladder (c). Moderate F-18 fluorocholine uptake is also noted in subcentimetric aortocaval (maximum standardized uptake value 4.2) lymph nodes (d). The mild bilateral uptake in thorax is in hilar lymph nodes and is likely inflammatory in nature. T2-weighted magnetic resonance imaging image (e) show hypointense area in peripheral zone of prostate gland from 4 O' to 8 O' position, which on DWI-magnetic resonance imaging image (f) show mild diffusion restriction. No definite evidence of skeletal evidence was noted in whole-body Tc-99 m methylene-diphosphonate bone scan image (g)

Figure 3

A 58 years old man on hormonal therapy with rising prostate-specific antigen (21.5 ng/mL) underwent whole-body F-18 fluorocholine positron emission tomography–computed tomography (a-c) and Tc-99 m methylene-diphosphonate bone scan (d and e) for recurrence evaluation. Abnormal uptake on the MIP image (a) localizes to tracer avid lesion in left iliac (maximum standardized uptake value 9.3) on transaxial fused computed tomography (b) and positron emission tomography–computed tomography (c) images. Tc-99 m methylene-diphosphonate bone scan (d and e) shows mild focal uptake just lateral to the inferior part of the left sacroiliac joint (arrow), on both anterior and posterior images is likely to be metastatic in nature. Single-photon emission computed tomography/computed tomography for this region was also planned but could not be performed