MR thermometry guidance of HIFU thermal ablation of peripheral nerves.

<p>Temperature maps (top) indicate peak temperature of 82.5°C. Thermal dose maps (bottom) predict lesion size of 12 x 29 mm.</p

Light microscopy images of nerves, H&E staining.

<p><b>A</b> Untreated peripheral nerve at 5x magnification. <b>B</b> Treated peripheral nerve (6 mm distal to center of ablation) at 5x magnification showing epineurial collagen homogenization (a), vascular congestion (b), widening of the subperineural space (arrow). <b>C</b> Untreated peripheral nerve 40X detail of axons and Schwann cells. <b>D</b> Treated peripheral nerve 40x detail showing regressive nuclear changes karyolysis (dashed arrow) and pyknosis (arrow) and vacuolization (arrowhead).</p

MR neurography of pig sciatic nerve before (top) and after (bottom) MR-HIFU.

<p>SHINKEI images reconstructed as thick-slab (15 mm) maximum intensity projections in sagittal, axial, and coronal orientations.</p

Light microscopy images at 40x magnification of semi-thin (1.5 μm) toluidine blue stained sections A Normal appearance of myelinated (arrow) nerve fibers in a cross section. B Pallor and irregularity of myelin (arrow) and vacuolization (a) in a HIFU-treated nerve segment.

<p>Light microscopy images at 40x magnification of semi-thin (1.5 μm) toluidine blue stained sections A Normal appearance of myelinated (arrow) nerve fibers in a cross section. B Pallor and irregularity of myelin (arrow) and vacuolization (a) in a HIFU-treated nerve segment.</p

Boxplot of lesion diameter and length in 12 mm treatment cells (n = 5) as measured on imaging, thermometry and macroscopy.

<p>Boxplot of lesion diameter and length in 12 mm treatment cells (n = 5) as measured on imaging, thermometry and macroscopy.</p

MRI evaluation of thermal lesions in peripheral nerve.

<p>Hyperintense region on 3D diffusion-prepared MR neurography (top) corresponds with non-enhancing region on T1 post-contrast image.</p

Targeting of peripheral nerve using MR-HIFU treatment planning system.

<p>The sciatic nerve is hyper-intense on MR neurography and iso-intense on T1 where dual-bundle structures are seen against fat. HIFU beam overlay (white) indicates 12 mm diameter target region.</p

Light microscopy images of peripheral nerves at 40x magnification, Masson’s trichrome staining.

<p><b>A</b> Normal appearance of myelin on Masson’s trichrome; myelin sheaths stain purple-red (black arrow). <b>B</b> Section of treated peripheral nerve at the center of the lesion showing absence of purple-red staining (arrow) indicating acute damage to the myelin sheaths. Asterisk (*) indicates subperineural edema.</p