Year : 2022 | Volume
: 38 | Issue : 4 | Page : 321--322
Comparison of multiparametric ultrasound versus multiparametric magnetic resonance imaging for diagnosis of carcinoma prostate: The CADMUS trial
Department of Urology, All India Institute of Medical Sciences, Bhubaneswar, Odisha, India
Department of Urology, All India Institute of Medical Sciences, Bhubaneswar, Odisha
|How to cite this article:|
Tarigopula V. Comparison of multiparametric ultrasound versus multiparametric magnetic resonance imaging for diagnosis of carcinoma prostate: The CADMUS trial.Indian J Urol 2022;38:321-322
|How to cite this URL:|
Tarigopula V. Comparison of multiparametric ultrasound versus multiparametric magnetic resonance imaging for diagnosis of carcinoma prostate: The CADMUS trial. Indian J Urol [serial online] 2022 [cited 2023 Jan 30 ];38:321-322
Available from: https://www.indianjurol.com/text.asp?2022/38/4/321/357724
The cancer diagnosis by multiparametric ultrasound (mpUS) of the prostate (CADMUS) was a prospective, paired cohort, multicenter trial conducted across seven hospitals in the UK to compare cancer detection by multiparametric magnetic resonance imaging (mpMRI) versus mpUS. The authors recruited 370 patients with abnormal digital rectal examination, elevated prostate-specific antigen (PSA) levels, and those with a biopsy-proven disease who required further risk stratification. Patients with PSA levels higher than 20 ng/ml, prostatic size greater than 60 ml, recent transurethral prostate surgery, or imaging suggestive of node positivity or distant metastasis were excluded. All the patients were subjected mpMRI and mpUS which comprised four components: B-mode, real-time-elastography, color-Doppler, and contrast-enhanced ultrasound. Positive lesions on either modality were subjected to targeted biopsies. If both the tests picked up positive lesions, the sequence of lesions to be biopsied first was randomized. The patients and pathologists were masked. The proportion of positive tests, detection of clinically significant cancer (CSC) of Gleason score 4+3 or higher, or a cancer core length of 6 mm or longer of any grade according to the PROMIS trial definition were the co-primary endpoints.
mpUS was positive in 89% of patients as opposed to 78% in mpMRI. There was 73.2% positive test agreement. mpUS detected CSC in 26% of patients, while mpMRI detected the same in 30% of patients. Overall, 32% of patients with CSC were picked up by both tests. However, it was noted that mpUS detected 7% of patients that were missed by mpMRI. Likewise, mpMRI detected 20% of patients that were missed by mpUS. The authors concluded that combining the two modalities would increase the detection rates of CSCs.
mpMRI is widely accepted as the standard radiological investigation before a prostatic biopsy and might avoid as many as 27% of patients from unnecessary biopsies. Some limitations with mpMRI are inaccessibility, costs, variability in scan quality or reporting, contraindication in patients with metallic implants, claustrophobia, low specificity, inter-reader variability, and lack of standardization of image acquisition. Search for alternative imaging modality is ongoing. Mannaerts et al. have previously shown that combining various ultrasound modalities as mpUS improved localization and sensitivity of cancer detection on comparing with radical prostatectomy specimens.
Although this study showed that mpUS detected 7% of CSCs that were missed by mpMRI, it also missed 20% of patients and subjected 11.1% more patients to prostatic biopsy. The overall detection rate of CSC was 4.3% less with mpUS. The study compared mpUS-targeted biopsy with another targeted biopsy rather than with an independent set of systemic samples. The study excluded patients with large prostates (more than 60 ml). Larger prostates, calcifications might decrease the diagnostic yield of mpUS. Applicability of mpUS in patients with PSA greater than 20 ng/ml was not studied. The protocol was amended to include 15 patients who underwent transrectal biopsy rather than transperineal biopsy. The location of target lesions in these 15 patients was not mentioned. Likert scale was used to score mpMRI and mpUS results, while radiologists are more familiar with the PIRADS scoring system. The visual estimation targeting technique was applied for targeted biopsies based on anatomical landmarks but it is not certain if suspicious lesions visible at the time of biopsy have also been targetted. There is heterogeneity in the type of MRI machine used and usage of endorectal coils during mpMRI. The biopsies were analyzed by independent pathologists at each center rather than a centralized pathology review.
Some newer ultrasound modalities such as high-resolution ultrasound and microultrasound have not been studied in this trial. The Likert system to assess mpMRI depends on the reader's experience. The Likert reporting scheme devised for mpUS in this study suffers from the same drawbacks as in mpMRI. Inter-reader variability and validity of reporting mpUS need to be studied further. Facilities without MRI machinery might not also have all the necessary equipment to perform mpUS or expertise to accurately interpret the results.
The results of the study are promising for using mpUS as an alternative diagnostic modality for CaP, especially in settings where mpMRI is unavailable or is contraindicated. However, further studies are required to assess the reproducibility and ease of use. Currently, one can only advocate mpUS at facilities where mpMRI is unavailable, or as an additional modality to improve detection rates.
Financial support and sponsorship: Nil.
Conflicts of interest: There are no conflicts of interest.
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