Magnetic resonance sentinel lymph node imaging and magnetometer-guided intraoperative detection in prostate cancer using superparamagnetic iron oxide nanoparticles

Abstract

PurposeSentinel lymph node (LN) dissection (sLND) using a magnetometer and superpara-magnetic iron oxide nanoparticles (SPION) as a tracer was successfully applied in prostate cancer (PCa). The feasibility of sentinel LN (SLN) visualization on MRI after intraprostatic SPION injection has been reported. In the present study, results of preoperative MRI identification of SLNs and the outcome of subsequent intraoperative magnetometer-guided sLND following intraprostatic SPION injection were studied in intermediate- and high-risk PCa.Patients and methodsA total of 50 intermediate- and high-risk PCa patients (prostate-specific antigen >10 ng/mL and/or Gleason score ≥7) scheduled for radical prostatectomy with magnetometer-guided sLND and extended pelvic LND (eLND), were included. Patients underwent MRI before and one day after intraprostatic SPION injection using T1-, T2-, and T2*-weighted sequences. Diagnostic rate per patient was established. Distribution of SLNs per anatomic region was registered. Diagnostic accuracy of sLND was assessed by using eLND as a reference standard.ResultsSPION-MRI identified a total of 890 SLNs (median 17.5; IQR 12–22.5). SLNs could be successfully detected using MRI in all patients (diagnostic rate 100%). Anatomic SLN distribution: external iliac 19.2%, common iliac 16.6%, fossa obturatoria 15.8%, internal iliac 13.8%, presacral 12.1%, perirectal 12.0%, periprostatic 3.7%, perivesical 2.3%, and other regions 4.4%. LN metastases were intraoperatively found in 15 of 50 patients (30%). sLND had a 100% diagnostic rate, 85.7% sensitivity, 97.2% specificity, 92.3% positive predictive value, 94.9% negative predictive value, false negative rate 14.3%, and 2.8% additional diagnostic value (LN metastases only outside the eLND template).ConclusionMR scintigraphy after intraprostatic SPION injection provides a roadmap for intraoperative magnetometer-guided SLN detection and can be useful to characterize a reliable lymphadenectomy template. Draining LN from the prostate can be identified in an unexpectedly high number, especially outside the established eLND template. Further studies are required to analyze discordance between the number of pre- and intraoperatively identified SLNs.

Accuracy of Magnetometer-Guided Sentinel Lymphadenectomy after Intraprostatic Injection of Superparamagnetic Iron Oxide Nanoparticles in Prostate Cancer: The SentiMag Pro II Study

“…Similarly, in the SentiMag Pro II Study, the number of SLNs removed (median 9, IQR 6-12) was higher than described in our own previous studies using the technetium-based procedure, in which 6 SLNs (median; IQR 4-8) were resected [5]. A possible cause for this could be the smaller size of SPION (60 nm; 99m Tc nanocolloid: <80 nm) which could result in marking of secondary landing sites, too [19].…”

“…In contrast, the spatial resolution of radioisotope-based lymphoscintigraphy is quite limited (~7-8 mm), which makes identification of smaller LNs, typical of pelvic LNs, difficult. The differentiation of SLNs, especially in the periprostatic, presacral, and perirectal region, is difficult because of high periprostatic activity and excreted radiotracer in the bladder [19].…”

New Developments in Imaging for Sentinel Lymph Node Biopsy in Early-Stage Oral Cavity Squamous Cell Carcinoma

“…Following peritumoral administration of SPIOs, transportation through the lymphatic system is mainly facilitated by macrophages, although unbound transport is seen as well [ 47 ]. SPIO accumulates primarily in lymph node sinuses and can be detected preoperatively on MRI and intraoperatively with a handheld magnetometer [ 23 , 47 , 48 , 49 , 50 ]. MR lymphography using SPIO has been investigated for several tumor types, including breast and prostate cancer [ 48 , 49 ].…”

Magnetic Resonance Sentinel Lymph Node Imaging and Magnetometer-Guided Intraoperative Detection in Penile Cancer, using Superparamagnetic Iron Oxide Nanoparticles: First Results

“…To overcome these impediments, SPION have been successfully used to identify SLNs in breast cancer [5]. Recently, we presented the first results of preoperative visualization and intraoperative detection of SLNs in prostate cancer, using a magnetic tracer, MRI, and a handheld magnetometer [7,8]. Because of the unavailability of 99m technetium or nuclear medicine facilities, we used this magnetic sentinel approach in 2 patients with cN0 penile cancer.…”

“…The first patient underwent magnetic resonance imaging (MRI) for preoperative visualization of SLNs. The MRI study was conducted using a 1.5-T MRI Scanner (MAGNETOM Aera; Siemens, Erlangen, Germany) as previously described [7,8]. The acquisition of the MR images started one and a half hour after injection.…”