Researchers in Houston have developed the first molecular image-guided system to diagnose and treat small-cell peri-
pheral lung cancer, a system that they believe could revolutionize the way the disease is managed.
Early-stage lung lesions (< 1.5 cm) are detected with image-guided technology, and malignant lesions are treated with radiofrequency ablation (RFA) right away, obviating the need for surgical intervention and the associated risk of mortality, according to the investigators, led by Stephen T.C. Wong, PhD, vice chair of the department of radiology and director of the Center for Bioengineering and Informatics at The Methodist Hospital Research Institute (Comput Med Imaging Graph 34:55-60, 2010).
The technique may also be cost-effective compared with the current sequential procedures of biopsy, diagnosis, and treatment, according to the researchers.
Currently, lung cancer diagnoses entail four different imaging studies, including percutaneous biopsies and subsequent transthoracic CT-guided needle biopsies, that could take days or weeks to complete.
Dr. Wong said that his technique "integrates all the previously disparate components, including CT, optical microendoscopy, electromagnetic (EM) tracking, RFA, real-time segmentation, and 3D visualization, seamlessly to produce clinically relevant results for image-guided intervention of peripheral lung cancer." A fiberoptic probe with an attached camera, guided by EM tracking and preoperative volumetric CT imaging, provides real-time images of the lesions.
The intervention system is based on a joint algorithm involving iterative serial image registration and segmentation procedures to improve the robustness and temporal stability of image processing.
Dr. Wong has received a research grant of $1.15 million from the Cancer Prevention & Research Institute of Texas in Austin to develop the image visualization and navigation software compatible with commercially available image-guided therapy platforms for clinical application. Interventional radiologist Marshall Hicks, MD, acting chair of diagnostic radiology at M.D. Anderson, is the clinical collaborator on the IGT project.
Commentary
The technology represents "a very important advance and an incremental improvement in technological sophistication to accurately scan peripheral lung cancer lesions in real- time in a breathing patient for radiological intervention," said Stephen M. Hahn, MD, professor and chair of the department of radiation oncology at the University of Pennsylvania School of Medicine in Philadelphia.
Dr. Hahn also said that large datasets of patients need to be prospectively studied to establish any safety and efficacy claims. He added that stereotactic radiosurgery is still accurate in early-stage lung disease, although he does not currently have data that show RFA is better.
The article from Dr. Wong and colleagues demonstrates a technique for rapid elastic warping of the images in order to be able to make adjustments for patient, organ, or target motion. This technique could improve the overall diagnosis and treatment process, said Dr. Wood, director of the Center for Interventional Oncology and chief of interventional radiology at the NIH in Bethesda, Md.
"Matching the pre-procedural patient lung CT images with the intra-procedural magnetic space is the key," said Dr. Wood. However, he noted that "the paper addresses just one component of the whole paradigm...Needle guidance and target definition based on a combination of ultrasound, CT, PET, and MRI fusion could enable more accurate targeting than standard techniques. Such improved accuracy can directly impact patient outcomes for RFA and biopsy, as shown in an NIH clinical trial" (RSNA 2009 abstract RC617B).
Image-guided minimally invasive therapies have become pillars of local and regional oncologic therapy. Dr. Wong's group reports on "just one piece in the overall paradigm, and the specific benefit to patients for such systems is still undefined, but improved accuracy should translate to improved outcomes, although it is too early to arrive at claims of efficacy," Dr. Wood said.
"In many cases, loco-regional therapy may be a 'band-aid' for palliation or debulking and is sometimes limited to inoperable patients or those with surgical risks and comorbidities, although many would argue that it may be an alternative to surgery in specific clinical settings," he said.
Dr. Wood added that long-term data from randomized controlled trials in lung cancer are still lacking and sorely needed.
