The rarity of bone and soft tissue sarcomas heightens the value of having an expert radiologist on the sarcoma team. "Many benign masses can mimic sarcomas, and vice versa, so establishing the correct diagnosis is incredibly important," says Lynne Steinbach, M.D., professor of radiology at UCSF.
When initial imaging studies fail to make clear whether musculoskeletal lesions are malignant or benign — or what type of tumors they might be — radiologists' access to and expertise with a full range of modern imaging modalities, their experience with image-guided biopsies, and their close collaboration with other specialists can improve diagnoses and, in turn, patient outcomes.
Depending on the individual situation, after an MRI or CT scan radiologists might move to a PET-CT scan, which has a number of advantages for diagnosing tumors. "Radiotracer uptake can often indicate malignancy," says Steinbach. In addition, PET-CT scans can reveal other tumor sites, be they primary or metastatic.
If the tumor is not necrotic, fluid or mucinous, image-guided biopsy is another option, says Thomas Link, M.D., professor of radiology and chief of musculoskeletal imaging at UCSF, who has done approximately 150 of these procedures over the last four years.
"An image-guided biopsy is appropriate after all imaging studies have been reviewed, and you need a definite diagnosis for therapeutic management of an aggressive, potentially malignant tumor," says Link.
Link's experience in doing core biopsies using larger-gauge needles has improved their accuracy over fine-needle aspirations and decreased the risks. At UCSF Medical Center, the presence during the procedure of a pathologist or cytologist who can quickly assess whether the radiologist has harvested a large enough core helps avoid repeated procedures.
Perhaps most important, "Knowing the proper approach is essential to avoid contamination of the surrounding structures, which can make the subsequent surgery more difficult and cause more complications," says Link.
Consequently, collaboration with the orthopaedic surgeon at the center where the procedure will be done is essential. At UCSF, radiologists participate in regular meetings of multidisciplinary sarcoma and tumor boards that include orthopaedic and general surgeons as well as pathologists, radiation oncologists and hematologists/oncologists.
To contact Dr. Thomas Link, call (415) 353-4921.
UCSF Medical Center is among the most active sites in California for an interventional radiologic technique known as CT-guided, percutaneous, radiofrequency thermal ablation. The technique can remove chondroblastomas, metastases and chordomas, but to date is used mostly to ablate painful osteoid osteomas.
"For osteoid osteomas, our follow-up shows the pain is gone for 90 percent of our patients," says Thomas Link, M.D., who performs about one of these procedures each month.
Radiofrequency thermal ablation is a minimally invasive procedure with no drilling and resultant scars that are typically less than five millimeters. After careful planning based on imaging studies, Link chooses either a 10mm or 7mm probe, based on the size of the nidus. Then, with patients under general anesthesia, Link ablates the area as well as the margins.
"Because diagnosis and choosing the proper approach are essential, it's important to do these procedures in centers where the interventional radiologist has a lot of experience," says Link.
For more information about this technique, visit www.radiology.ucsf.edu/patients/rfa.
Stem Cells and Tissue Regeneration
With a major stem cell research grant, Ophir Klein, M.D., Ph.D, is exploring the molecular processes that regulate the behavior of dental stem cells in mice, with the goal of promoting tooth regeneration and treating craniofacial abnormalities in humans.