Sherif Gamal Nour

A technique for MRI-guided transrectal deep pelvic abscess drainage.

OBJECTIVE The purpose of this article is to introduce a technique for transrectal drainage of deep pelvic abscesses performed under interactive MRI guidance. CONCLUSION A new method for triorthogonal image plane MRI guidance was developed and used to interactively monitor the puncture needle on continuously updated sets of adjustable three-plane images. The merits and limitations of the technique are highlighted and the patient population that is likely to benefit from this approach is suggested.

Magnetic resonance imaging and model prediction for thermal ablation of tissue

To monitor and predict tissue temperature distributions and lesion boundaries during thermal ablation by combining MRI and thermal modeling methods.

MR Monitoring of NaCl-enhanced Radiofrequency Ablations: Observations on Low- and High-Field-Strength MR Images with Pathologic Correlation

PURPOSE To test the hypothesis that magnetic resonance (MR) imaging can be used to monitor both intraparenchymal injection of NaCl solution and subsequent radiofrequency ablation (RFA) within tissues pretreated with NaCl, report the low- and high-field-strength MR appearance of NaCl-enhanced RFAs, and compare MR findings with pathologic findings. MATERIALS AND METHODS Ten ex vivo calf liver specimens were injected with saturated NaCl (seven were mixed with methylene blue during MR fluoroscopic monitoring) and reexamined with fast imaging with steady-state progression (FISP), true FISP, reversed FISP (PSIF), and fast spin-echo T2-weighted MR sequences. The NaCl-to-liver contrast-to-noise ratio (CNR) was calculated for various sequences, and CNRs were compared with the Student t test. Distribution on MR images was compared with the results of pathologic analysis. Forty additional in vivo monopolar RFAs were performed in paraspinal muscles of seven minipigs after animal care committee approval (10 standard control ablations, 30 were preceded by direct injection of saturated NaCl at various volumes [3-9 mL] and rates [1 or 6mL/min]). Postablation low-field-strength (n = 20) and high-field-strength (n = 20) MR examinations consisted of T2-weighted imaging, short inversion time inversion-recovery (STIR) imaging, and contrast material-enhanced T1-weighted imaging. Ablation shape, conspicuity, volume, and signal intensity were compared between the two groups and with the results of pathologic analysis. The difference in volumes with and without NaCl injection was evaluated by using two-way analysis of variance. RESULTS Mean CNR was highest on fast spin-echo T2-weighted images and was significantly higher for PSIF than for FISP (P < .0001) or true FISP (P = .003). NaCl distribution on MR images corresponded with the results of pathologic analysis in ex vivo livers. Interactive in vivo monitoring of NaCl injection and electrode placement was feasible. NaCl-enhanced ablations had irregular shapes, a higher CNR, and significantly larger volumes (F = 22.0; df = 1, 90; P < .00001). All ablations had intermediate or low signal intensity with high-signal-intensity rims on all images. Fluid signals overlaid NaCl-enhanced ablations on fast spin-echo T2-weighted and STIR images, particularly on high-field-strength MR images. CONCLUSION MR imaging can be used to reliably monitor the distribution of injected NaCl solution in tissues. Interventional MR imaging techniques can be used to guide and monitor RFAs within NaCl pretreated tissues, with good correlation with pathologic results.

Magnetic Resonance Imaging-Guided and -Monitored Radiofrequency Interstitial Thermal Cancer Ablation

minimizing invasiveness while upgrading the efficacy of treatment and effectively utilizing medical resources in a cost-effective manner. Similarly, interventional radiology has emerged and evolved over the past quarter century so that a majority of its procedures are performed in the setting of cancer patient care. Under conventional fluoroscopic, ultrasound, or computed tomography (CT) guidance, interventions range from straightforward diagnostic procedures, such as biopsy and aspiration, to a more complicated array of palliative/therapeutic procedures, such as tumor embolization, biliary and hollow viscous stenting, percutaneous gastrostomy, celiac plexus and other nerve blocks, inferior vena cava filter application, and percutaneous imageguided brachytherapy. As the art of oncologic therapy advances and extends the horizons for cancer management, parallel innovations in interventional radiology, particularly in interventional magnetic resonance imaging (MRI), have a tremendous potential to assume a central role in the continued progress of cancer therapy beyond the traditional surgery–radiotherapy–chemotherapy triad. There are numerous exciting topics in this field that are expected to en-