Ortiz O, guest ed. Mukherji SK, consulting ed. Imaging of the Postoperative Spine. Elsevier; June 2014. Neuroimaging Clinics of North America; vol. 24; no. 2; pgs. 269–394; $489.00
Dr. Ortiz, as editor of this latest volume of Neuroimaging Clinics of North America, indicates that images of the postoperative spine are among the least favorite studies to be interpreted by his colleagues. This is nearly a universal feeling and probably results from both unfamiliarity with specifics of the surgery and how the findings on CT or MR may correlate with the clinical situation. Because of this, Imaging of the Postoperative Spine is a worthwhile publication (May 2014). While many spine surgeons have a good understanding of the significance of the imaging findings, there is no doubt that an astute and knowledgeable radiologist will be able to make key observations, helpful in patient management.
This book contains 9 chapters written by 23 authors. The titles are “Imaging of Lumbar Fusion,” “Motion Preservation Surgery,” “The Postoperative Spine: What the Spine Surgeon Needs to Know,” “Postoperative Spine Imaging in Cancer Patients,” “Post-Vertebral Augmentation in Spine Imaging,” “Optimized Imaging and Management of Postoperative Spine Infections,” and “Radiologic Evaluation and Management of Postoperative Spine/Paraspinal Fluid Collections.” To this reviewer, there should have been an additional chapter, perhaps written by a spine surgeon, dedicated more directly to the various approaches to the degenerative spine, the hardware used, and the rationale for those different approaches, with illustrations of each. Although there is some material on surgical approaches in parts of the book, it is too scant and there isn’t a chapter which pulls this all together. Drs. Wilson and Ross explain the approaches, but a separate chapter with artist drawings showing the procedures would have been a nice touch. For example: when an ALIF is used, or why perform an XLIF when a more standard TLIF is available, and so on.
Also, the book is heavily slanted towards the lumbar spine, so the title of this issue would have been more accurately called Imaging of the Postoperative Lumbar Spine. If the desire was to include the entire spine, then areas are missing, such as cervical laminoplasty, instrumented laminoplasty, and cervical strut grafting, as just a couple of examples.
All that being said, there is value in the material covered, although the reader will not come away knowing why, with certain preoperative imaging and clinical findings, a certain procedure was performed. This book could have been a perfect opportunity to include such material.
In the chapter on lumbar spine fusion there is a summary and illustrations for judging fusion effectiveness. While it is well recognized that a new neurologic deficit or unexpected pain is a reason to obtain imaging, what would have been nice would have been description of when follow-up imaging should be obtained in judging the fusion in those patients who have no new symptoms. In other words, is it proper to obtain imaging in the absence of any new symptoms in order to judge the efficacy of the fusion, and if so, when? There is a chart that shows the stages and signs of fusion; however, does this mean that every postfusion patient gets imaging at 3 months, 6 months, and 12 months, even in the absence of new symptoms? This is probably not a standard in orthopedic or neurological spine surgery, with many surgeons eschewing CT imaging in asymptomatic postoperative patients.
For those unfamiliar with devices used in motion presentation, the chapter by Murtagh and Castellvi will be informative (a nice tribute to Dr. Castellvi by Dr. Murtagh appears at the end of the chapter). By reading this material, one gains an insight into the rationale of lumbar and cervical disc replacement, the concept being to avoid a rigid back and thereby avoid stress on levels adjacent to the fusion.
A persistent problem in evaluating the postoperative spine is judging whether the findings one sees are the normally expected edema, enhancement, small fluid collections, and bone irregularities, or whether one is dealing with an infection, particularly when it is in a pre-abscess stage. The chapters by Wilson/Ross and by Mazzie/Brooks/Greire deal nicely with this problem, but of course there will remain some borderline or indefinite cases, where the clinical laboratory parameters will be crucial.
While most of the imaging shown in the book is adequate to demonstrate the described findings, there are a few instances where better attention to image quality would have helped. As one example, on CT lucency (described in caption) around a screw is virtually impossible to see because of poor photographic windowing. Similar observations are made on some MR imaging. In another instance the FOV is large, with the axial spine image occupying a small percent of the figure.
The chapter that describes optimizing the imaging of the postoperative spine is important and well-constructed. The reader learns the techniques used in both CT and MR to diminish the effect of disturbing artifacts that are present because of implanted hardware. Techniques are described with CT, such as dual energy, techniques from different vendors, high KVP, iterative reconstruction, voxel/slice size, and, with MR, bandwidth, ETL, and gradient orientation, among other techniques.
It is proper to compare this issue of the Clinics with another recently published book on the same subject. In this reviewer’s opinion, for overall coverage, the Specialty Imaging: Postoperative Spine (published by Amirsys, edited by Jeff Ross) is a stronger publication.
Nonetheless, overall, this is a recommended publication and fits in well with Dr. Mukherji’s intent on presenting practical topics within the series of NICNA.
