Cardiac PET/CT gains clinical recognition

Cardiologists impressed by the diagnostic power of PET/CT are beginning to recognize its clinical importance. In sites where the transition from PET to PET/CT has been made, rising cardiac PET imaging volumes have followed. Although the promise of improved cancer imaging originally led radiologists at Brigham and Women's Hospital in Boston to acquire their first PET/ CT scanner, the ability to fuse functional PET with anatomically detailed CT and CT angiography images has gained the support of cardiologists as well.

"We have seen a rapid conversion from PET to PET/CT because of applications in oncology. As a result, PET/CT use has grown along with cardiac imaging," said Dr. Marcelo DiCarli, director of cardiovascular imaging at Brigham and Women's.

Once exclusively the domain of academic practitioners, cardiac PET/CT is winning over more community-based physicians. Dr. Randy Patterson, a nuclear cardiologist at Emory Crawford Long Hospital in Atlanta, estimates that half of the patients referred for cardiac PET imaging at his outpatient clinic originate from private-practice physicians. Cardiac PET/CT imaging volume at Emory's affiliated hospitals and clinics is expected to reach 3300 cases in 2006.

"The images are so much easier to interpret than SPECT," Patterson said. "You can feel so much more confident in what you're seeing."

UPSIDE TO PAYMENT CUTS

Although cardiac PET/CT is still considerably more expensive than thallium-201 or technetium-99m MIBI SPECT, threatened cuts in PET/CT reimbursement actually promise to increase its popularity, said Dr. Rory Hachamovitch, a cardiologist and visiting associate professor of clinical medicine at the University of Southern California.

The introduction of more flexible contracts for rubidium generators has made cardiac PET/CT more practical. Facilities can now contract for weekly or biweekly access, instead of mandatory access throughout the entire month, DiCarli said. Brigham and Women's Hospital is billed by the unit dose, although it still has full-time access to a rubidium generator.

"PET/CT is what MR claimed to be for years but wasn't-the one-stop shop for imaging," Hachamovitch said. "We haven't heard more about it because PET has often been the domain of nuclear medicine and radiology. It is only now that cardiologists are becoming aware that it exists and that they can use it for many of their patients."

Perfusion PET assesses myocardial function, while CTA covers coronary anatomy. CT also simultaneously provides PET attenuation correction and captures imaging data for calcium scoring.

"It offers the whole gamut of atherosclerosis and coronary assessment and ischemia assessment and functional assessment, all in one package," he said.

IMAGING OBESE PATIENTS

Radiologists and cardiologists have begun to recognize that PET offers superior results over other options for morbidly obese patients. PET/CT's ability to accommodate patients weighing up to 450 pounds has led to a flood of new cardiac imaging PET/CT orders at Emory University, Patterson said.

"For obese patients, you get a better image with PET than you ever would with SPECT," he said.

PET/CT is especially useful after an equivocal or nondiagnostic SPECT study, Patterson said. Emergency room physicians are increasingly ordering it for chest pain patients who have a moderate risk of myocardial infarction. The studies allow them to rule out MI with greater confidence, thereby avoiding unnecessary hospital admissions.