J Korean Soc Spine Surg. 2013 Mar;20(1):28-33. Korean.
Published online Mar 31, 2013.
© Copyright 2013 Korean Society of Spine Surgery
Original Article

Usefulness of the ProSet MRI for Diagnosis of the Extraforaminal Disc Herniation

Myun-Whan Ahn, M.D., Ui-Sik Kim, M.D. and Gi-Beom Kim, M.D.
    • Department of Orthopaedic Surgery, Yeungnam University Hospital, Daegu, South Korea.
Received November 08, 2012; Revised December 27, 2012; Accepted March 18, 2013.

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Study Design

This is a retrospective study.

Objectives

The purpose of this study is to confirm the clinical usefulness of utilizing ProSet imaging for checking the nerve root compression and swelling in extraforaminal disc herniation.

Summary of Literature Review

Diagnosing extraforaminal disc herniations can be neglected with using a conventional MRI.

Materials and Methods

A retrospective analysis was performed on 25 patients, who underwent both conventional & Principles of the selective excitation technique (ProSet) MR imaging for the evaluation of extraforaminal disc herniation, from April 2008 to October 2010. Radiographic analysis was based on the notion that the degree of nerve root compression and swelling was decided by Pfirrmann's classification.

Results

Severe compression in the ProSet 3D rendering image was observed in 21 subjects, as compared with 8 subjects in the conventional axial image. Especially, nothing was ever detected in the conventional sagittal image. Severe compression in the ProSet 3D rendering image was observed in 4 subjects, while their nerve root compression was not clear in the conventional axial image. Severe compression and severe swelling in the ProSet 3D & coronal image was observed in 15 subjects, while their nerve root compression was none or not clear in the conventional sagittal image. The swelling degree of the ProSet coronal image turned out bigger than the swelling degree of conventional axial image, and the signal intensity change was also obvious.

Conclusions

ProSet imaging is regarded useful to investigate the symptom triggering nerves, because ProSet image not only observes better nerve root compression, but also identifies the swelling degree more easily than that of the conventional magnetic resonance imaging (MRI).

Keywords
Extraforaminal disc herniation; MRI; Principles of the selective excitation technique (ProSet) MRI

Figures

Fig. 1
Schematic diagram of a system for grading lumbar nerve root compromise in coronal plane and axial plane. (A) No compromise of the nerve root. (B) Contact of disc material with the right exiting nerve root. The nerve root is in the normal position and is not dorsally deviated. (C) Dorsal deviation of the right exiting nerve root caused by contact with disc material. (D) Compression of the right exiting nerve root between disc material and the surrounding structure (e.g. pedicle). It may be appear flattened or be indistinguished from disc material.

Fig. 2
Comparison of conventional MRI axial view and Proset coronal view, extraforaminal herniation extended to the foramen at L5-S1. (A) Axial T2-weighted image shows left extraforaminal disc herniation with extension to foramen at L5-S1. (B,C) Swelling of the L5 nerve root(arrow) on Proset coronal view and 3D MR radiography is seen.

Fig. 3
Comparison of conventional MRI axial view and Proset coronal view of right extraforaminal herniation at L4-5. (A) Axial T2-weighted image shows contact of disc material with the right L4 exiting nerve root. The nerve root is in the normal position and is not dorsally deviated. (Pfirmann stage 1). (B,C) Swelling and compression of the right L4 exiting nerve root (arrow) between disc material and surrounding structure on Proset coronal view and 3D MR radiography is seen (Pfirmann stage 3).

Tables

Table 1
Compression grades according to classification with relation to the types of MR image in extraforaminal disc herniation of the lumbar spine

Table 2
Nerve root compression grade in the conventional axial image with relation to the ProSet 3D rendering image grade according to Pfirrmann's classification.

Table 3
Nerve root compression grade in the conventional sagittal image with relation to the ProSet 3D rendering image grade according to Pfirrmann's classification.

Table 4
Degrees of the Nerve root swelling and signal intensity with relation to the types of MR image in the extraforaminal disc herniation of the lumbar spine

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