Arterial spin labelling MRI to measure renal perfusion: a systematic review and statement paper

Renal perfusion provides the driving pressure for glomerular filtration and delivers the oxygen and nutrients to fuel solute reabsorption. Renal ischaemia is a major mechanism in acute kidney injury and may promote the progression of chronic kidney disease. Thus, quantifying renal tissue perfusion is critically important for both clinicians and physiologists. Current reference techniques for assessing renal tissue perfusion have significant limitations. Arterial spin labelling (ASL) is a magnetic resonance imaging (MRI) technique that uses magnetic labelling of water in arterial blood as an endogenous tracer to generate maps of absolute regional perfusion without requiring exogenous contrast. The technique holds enormous potential for clinical use but remains restricted to research settings. This statement paper from the PARENCHIMA network briefly outlines the ASL technique and reviews renal perfusion data in 53 studies published in English through January 2018. Renal perfusion by ASL has been validated against reference methods and has good reproducibility. Renal perfusion by ASL reduces with age and excretory function. Technical advancements mean that a renal ASL study can acquire a whole kidney perfusion measurement in less than 5–10min. The short acquisition time permits combination with other MRI techniques that might inform drug mechanisms and renal physiology. The flexibility of renal ASL has yielded several variants of the technique, but there are limited data comparing these approaches. We make recommendations for acquiring and reporting renal ASL data and outline the knowledge gaps that future research should address

Magnetic Resonance Imaging Follow-up of Targeted Biopsy-negative Prostate Lesions

BACKGROUND: The optimal radiological follow-up of prostate lesions negative on magnetic resonance imaging (MRI)-targeted biopsy (MRI-TB) is yet to be optimised. OBJECTIVE: To present medium-term radiological and clinical follow-up of biopsy-negative lesions. DESIGN, SETTING, AND PARTICIPANTS: The records for men who underwent multiparametric MRI at the UCLH one-stop clinic for suspected prostate cancer between September 2017 and March 2020 were reviewed (n = 1199). Patients with Likert 4 or 5 lesions were considered (n = 495), and those with a subsequent negative MRI-TB comprised the final study population (n = 91). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Baseline and follow-up MRI and biopsy data (including prostate-specific antigen [PSA], prostate volume, radiological scores, and presence of any noncancerous pathology) were extracted from reports. The last follow-up date was the date of the last test or review in clinic. RESULTS AND LIMITATIONS: Median follow-up was 1.8 yr (656 d, interquartile range [IQR] 359-1008). At baseline, the median age was 65.4 yr (IQR 60.7-70.0), median PSA was 7.1 ng/ml (IQR 4.7-10.0), median prostate volume was 54 ml (IQR 39.5-75.0), and median PSA density (PSAD) was 0.13 ng/ml2 (IQR 0.09-0.18). Eighty-six men (95%) had Likert 4 lesions, while the remaining five (5%) had Likert 5 lesions. Only 21 men (23%) had a single lesion; most had at least two. Atrophy was the most prevalent pathology on MRI-TB, present in 64 men (74%), and followed by acute inflammation in 42 (46%), prostatic intraepithelial neoplasia in 33 (36%), chronic inflammation in 18 (20%), atypia in 13 (14%), and granulomatous inflammation in three (3%). Fifty-eight men had a second MRI study (median 376 d, IQR 361-412). At the second MRI, median PSAD decreased to 0.11 ng/ml2 (IQR 0.08-0.18). A Likert 4 or 5 score persisted only in five men (9%); 40 men (69%) were scored Likert 3, while the remaining 13 (22%) were scored Likert 2 (no lesion). Of 45 men with a Likert ≥3 score, most only had one lesion at the second MRI (28 men; 62%). Of six men with repeat MRI-TB during the study period, two were subsequently diagnosed with prostate cancer and both had persistent Likert 4 scores (at baseline and at least one follow-up MRI). CONCLUSIONS: Most biopsy-negative MRI lesions in the prostate resolve over time, but any persistent lesions should be closely monitored. PATIENT SUMMARY: Lesions in the prostate detected via magnetic resonance imaging (MRI) scans that are negative for cancer on biopsy usually resolve. Repeat MRI can indicate persistent lesions that might need a second biopsy

The Transatlantic Recommendations for Prostate Gland Evaluation with Magnetic Resonance Imaging After Focal Therapy (TARGET):A Systematic Review and International Consensus Recommendations

Background and objective: Magnetic resonance imaging (MRI) can detect recurrences after focal therapy for prostate cancer but there is no robust guidance regarding its use. Our objective was to produce consensus recommendations on MRI acquisition, interpretation, and reporting after focal therapy. Methods:A systematic review was performed in July 2022 to develop consensus statements. A two-round consensus exercise was then performed, with a consensus meeting in January 2023, during which 329 statements were scored by 23 panellists from Europe and North America spanning urology, radiology, and pathology with experience across eight focal therapy modalities. Using RAND Corporation/University of California-Los Angeles methodology, the Transatlantic Recommendations for Prostate Gland Evaluation with MRI after Focal Therapy (TARGET) were based on consensus for statements scored with agreement or disagreement. Key findings and limitations: In total, 73 studies were included in the review. All 20 studies (100%) reporting suspicious imaging features cited focal contrast enhancement as suspicious for cancer recurrence. Of 31 studies reporting MRI assessment criteria, the Prostate Imaging-Reporting and Data System (PI-RADS) score was the scheme used most often (20 studies; 65%), followed by a 5-point Likert score (six studies; 19%). For the consensus exercise, consensus for statements scored with agreement or disagreement increased from 227 of 295 statements (76.9%) in round one to 270 of 329 statements (82.1%) in round two. Key recommendations include performing routine MRI at 12 mo using a multiparametric protocol compliant with PI-RADS version 2.1 standards. PI-RADS category scores for assessing recurrence within the ablation zone should be avoided. An alternative 5-point scoring system is presented that includes a major dynamic contrast enhancement (DCE) sequence and joint minor diffusion-weighted imaging and T2-weighted sequences. For the DCE sequence, focal nodular strong early enhancement was the most suspicious imaging finding. A structured minimum reporting data set and minimum reporting standards for studies detailing MRI data after focal therapy are presented. Conclusions and clinical implications: The TARGET consensus recommendations may improve MRI acquisition, interpretation, and reporting after focal therapy for prostate cancer and provide minimum standards for study reporting. Patient summary:Magnetic resonance imaging (MRI) scans can detect recurrent of prostate cancer after focal treatments, but there is a lack of guidance on MRI use for this purpose. We report new expert recommendations that may improve practice.</p

Magnetic Resonance Imaging Follow-up of Targeted Biopsy–negative Prostate Lesions

International audienc