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Prostate carcinoma: Increased diagnosis quality Biopsy with magnetic resonance scanner
Verification of raised Prostate-Specific Antigen (PSA) levels
In cases involving manual diagnosis and/or PSA levels above 4 ng/ml, the initial diagnosis is usually verified using sextant biopsy in the form of transrectal ultrasound (TRUS). Due to the procedure, TRUS biopsy results are often negative even as PSA values increase. This inevitably leads to multiple examinations, patient discomfort and ultimately, to patient uncertainty as well.
A new interdisciplinary approach: Biopsy and MRI
Implementing a procedure that combines biopsy and MRI would improve the quality of the diagnosis because it would be possible to position the cannula more precisely using detailed realtime images. The requirements for this therefore had to be fulfilled. The generous open design of the MAGNETOM Espree and Symphony proved advantageous in this respect. However, a new solution had to be developed with regard to patient positioning, fixation and biopsy
The MRI-compatible biopsy device: A medical engineering innovation
The procedure is made possible by a new sliding-surface table, on which the supine patient is moved into the scanner after insertion of the cannula.
The table consists of a base plate, insertion section and mount, positioning section, biopsy gun, endorectal port and guide cannula. The procedure was thus able to be implemented and tested. The system was developed in cooperation with INNIVO/Daum GmbH.
Precise positioning for puncture is carried out using the images provided by the MAGNETOM Espree or Symphony in real time.
The advantages of the new procedure:
• No patient repositioning
• No sedation or anesthetization
• Increases patient comfort
• More reliable early detection
• Improvement of diagnosis quality
The study at a glance: Prostate biopsy with Magnetom 1.5 Tesla Scanner
From December 2003 to June 2006, 49 consecutive patients underwent MRI-guided prostate biopsy.
The patients had increased PSA levels and several ultrasound prostate biopsies with negative results already existed. Initially, an MRI examination was carried out with combined endorectal and body coil (phased-array coil). After localizing the areas suspected of tumors, the biopsy device was positioned without repositioning the patient. The guide cannula was positioned at the biopsy site under MRI guidance. Core biopsies were performed manually within the magnet. The average examination duration was two hours, depending on the number of biopsies carried out.
The results:
The cannula could be observed and positioned under MRI guidance in 49 cases. The smallest tumor formation that was successfully punctured was 5 mm in diameter. None of the patients had to be sedated or anesthetized. There were no side effects and no complications.
MR - Images
MRI images of a 74 year old patient with prostate carcinoma in the left peripheral zone (G2, Gleason 5). The axial endorectal image (A) shows a hypointense round lesion in the lateral left peripheral zone. The small lesion is clearly visible as a weak signal in front of the guide cannula in the pre-biopsy coronal TSE image (B). The axial (C) and coronal (D) TSE images show the tip of the cannula within the carcinomatous lesion.
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