MRI guidance in high-dose-rate brachytherapy for prostate cancer

doctoral thesis

• Author: Jure Murgić
• Mentor: Zvonko Kusić (mentor)
• Mentor: Cynthia Ménard (komentor)
• Committee member: nije dostupno (član povjerenstva)
• Granter: University of Zagreb; School of Medicine; Zagreb
• Defense date and country: 2017-05-25, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Clinical Medical Sciences
• Universal decimal classification (UDC): 61 - Medical sciences

Abstract

UVOD: Brahiterapija velikom brzinom doze je metoda izbora u visokodoznom zračenju raka prostate. Magnetska rezonanca (MR) pruža visoku slikovnu rezoluciju mekih tkiva i teoretski može poslužiti kao odlično sredstvo slikovnog navođenja brahiterapije velikom brzinom doze. BOLESNICI I METODE: Četrdeset (40) bolesnika s rakom prostate srednjeg ili visokog rizika uključeno je u prospektivnu kliničku studiju koju je odobrilo etičko povjerenstvo ustanove Princess Margaret Hospital. Multiparametrijska MR sa stereotaksijskom navigacijom je korištena u svrhu navođenja brahiterapijskih katetera, nakon čega je uslijedilo planiranje zračenja na osnovi MR.
REZULTATI: U okviru studije provedena su 62 brahiterapijska implanta. Medijan vremena potrebnog za inserciju katetera i oslikavanje bio je 100 minuta, dok je cjelokupno vrijeme trajanja anestezije bilo oko 4.0 sati (raspon 2.1-6.9 sati). MR korištena za vrijeme brahiterapije otkrila je da je u 14 (35%) bolesnika viši stadij bolesti nego što se prethodno smatralo. U 6 bolesnika ovo saznanje je koristilo u ciljanom navođenju brahiterapijskih katetera izvan granica prostate: slučaj ekstrakapsularnog širenja u 2 bolesnika te širenje bolesti u sjemene mjehuriće u 4 bolesnika. Većina bolesnika (80%) je imalo vidljiv tumor uočljiv na MR, koji je utjecao na raspored razmještanja katetera i planiranja zračenja. MR je opisao anatomske granice jasno nakon provedene implantacije, osim u slučaju apeksa prostate koji je bio zamagljen prisutnom krvlju nakon insercije katetera. Konvencionalna ograničenja doze za pokrivanje PTV (PTV V100>98%) i za rektum (V75<1.0 cc) bilo je teško zadovoljiti, no toksičnost metode je bila mala (akutna genitourinarna toksičnost većeg ili jednakog stupnja od 2 bila je 20%, kasna genitourinarna toksičnost većeg ili jednakog stupnja od 2 bila je 15%, kasna gastrointestinalna toksičnost većeg ili jednakog stupnja od 2 iznosila je 7%). Mehaničko oštećenje uretre viđeno na MR dovelo je do dvije ozbiljne nuspojave gradusa 3, koje su bile prolazne prirode.
ZAKLJUČAK: Unatoč standardnom brahiterapijskom pristupu, MR snimanje i slikovno vođenje tijekom brahiterapijske procedure promjenilo je raspored insercije katetera i strategiju planiranja zračenja. Klinički rad u brahiterapiji velikom brzinom doze u liječenju raka prostate upotrebom isključivo MR kao metode slikovnog navođenja je izvediv i siguran, no da bi bio opće prihvaćen potrebno ga je pojednostavniti.

Abstract (croatian)

INTRODUCTION: MRI has been widely accepted as the best imaging modality for prostate cancer. However, there is lack of knowledge how MRI perform when applied in MRI-only workflow for catheter insertion and treatment planning in patients receiving standard-care high-dose-rate (HDR) brachytherapy prior to external beam radiotherapy for prostate cancer.
PATIENTS AND METHODS: Forty patients with intermediate or high-risk prostate cancer were enrolled on a prospective clinical trial approved by institution’s research ethics board. Multiparametric MR imaging with stereotactic navigation was used to guide insertion of brachytherapy catheters, followed by MRI-based treatment planning.
RESULTS: Sixty-two implants were performed. Median catheter insertion + imaging time was 100 min, and overall anaesthesia time was 4.0 hours (range 2.1-6.9 hours). MRI at the time of brachytherapy re-staged 14 patients (35%) who were found to have a higher stage of disease. In 6 patients this translated in directed insertion of brachytherapy catheters outside of the prostate boundary (extracapsular disease (n=2) or seminal vesicle invasion (n=4)). Most patients (80%) had gross tumor visible on MRI, which influenced catheter insertion and treatment planning. MRI depicted post-implant anatomic boundaries clearly, with the exception of the apical prostate which was blurred by blood after catheter insertion. Conventional dose planning objectives for PTV coverage (PTV V100>98%) and for the rectum (rectal V75<1.0 cc) were difficult to achieve, but toxicities were low (acute grade≥2 genitourinary = 20%, late grade≥2 genitourinary = 15%, late grade ≥2 gastrointestinal = 7%).Urethral trauma visualized on MRI led to 2 transient grade 3 events.
CONCLUSION: Despite a standard-care treatment, MRI acquired throughout the procedure altered catheter insertion and dose-planning strategies. An MRI-only workflow is feasible and safe, but must be streamlined for broader acceptance.

• Keywords: medicine
• Keywords (croatian): medicina
• Language: english
• URN:NBN: urn:nbn:hr:105:126315
• Study programme: Title: Biomedicine and Health Sciences; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje biomedicine i zdravstva (doktor/doktorica znanosti, područje biomedicine i zdravstva)
• Type of resource: Text
• Extent: 84 str.
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-05-05 07:57:22