Appl Radiol. 2008;37(11):12-16.
Abstract and Introduction
Abstract
The
author performed the first virtual colonoscopy (VC) in 1993. In this
article, he addresses the issues related to the turf battles between
radiologists and gastroenterologists in the use of this technology.
Reviewing common myths associated with VC, he warns that radiologists
must retain expertise in this area.
Introduction
A storm
is brewing around virtual colonoscopy (VC) and whether radiologists or
gastroenterologists will ultimately control this technology. Imagine
the following: in the near future, a patient who requires colorectal
cancer (CRC) screening walks into a local gastroenterologist's office,
obtains a VC examination, which is read by a nurse practitioner, and,
following consultation with a gastroenterologist, undergoes immediate
optical colonoscopy (OC) for evaluation of tiny polyps that either
cannot be found or turn out to be residual feces. Meanwhile, a
radiologist working with this practice interprets the CT data for
extracolonic findings in exchange for a small percentage of the total
professional fee. The patient's insurance (ie, Medicare) is billed for
both the VC and OC, which taxpayers ultimately pay. If this sounds
far-fetched, read on....
Virtual Colonoscopy Development
Colorectal
cancer is the second leading cause of cancer death in the United
States, but it is also one of the most preventable when screening is
used to detect and treat early disease. The 5-year survival rate for
early stage I CRC is 93%, but when it metastasizes to distant organs
and becomes stage IV disease, the survival rate decreases to 8%.[1]
Unfortunately, many adults over the age of 50 do not undergo screening,
and, as a result, CRC is more often diagnosed in advanced stages.[2] Virtual colonoscopy offers the public a more appealing and less invasive alternative for screening.
I
performed the first VC, also known as CT colonography (CTC), at the
Wake Forest University Health Sciences Center in 1993. It has taken
nearly 15 years for VC to mature and gain acceptance by policy makers.
The basic technique consists of: 1) bowel cleansing and stool tagging,
2) gas insufflation of the colon, 3) CT scanning of the abdomen/pelvis,
and 4) 2- and 3-dimensional image analysis of the data to identify
polyps and masses (Figure 1). The first VC examination took 60 seconds
to scan a patient using a single-slice helical CT scanner and nearly 8
hours to process the data for a fly-through, but today multidetector CT
scanners acquire the data in a few seconds, and processing occurs in
real time using inexpensive computers.
Despite the technological advances that have occurred during the past decade (eg, CO2
insufflation, multidetector CT scanners, stool tagging,
computer-assisted diagnosis), a strong lobbying effort on the part of
gastroenterologists has delayed the availability of VC in the United
States. Since Congress approved reimbursement for CRC screening in the
1997 Balanced Budget Act, the number of colonoscopies conducted
annually in the United States has increased from 4 million in 2000 to
>14 million in 2002.[3]
Handwriting on the Wall
Clinical
trials that compared VC with OC have shown a dramatic improvement in VC
accuracy in the last few years, culminating in 2 major trials that were
announced in September 2007. The ACRIN National Colonography Trial
enrolled over 2500 patients at 15 sites, and it reported that VC had a
90% sensitivity for the detection of polyps >10 mm.[4] Within a week, Kim[5]
published a study comparing VC screening in 3120 patients with OC
screening in 3163 patients. Remarkably, VC and OC found an equivalent
number of advanced adenomas in each group; more surprisingly, a larger
number of cancers were found in the VC group.[5] These 2
studies plus multiple prior published trials from the United States and
abroad led the American Cancer Society, the American College of
Radiology (ACR), and the United States Multi-Society Task Force to
incorporate VC in its screening recommendations that were published in
March 2008.[6]
As VC has gained acceptance,
gastroenterologists now realize that VC will impact their practice.
After years of bashing VC as not being good enough and requiring more
clinical data, the Future Trends Committee of the American
Gastroenterological Association (AGA) published a report in October
2006 stating that they see the handwriting on the wall.[7]
This Committee proposed that gastroenterologists should position
themselves to play a role in performing and interpreting VC, including
advocating for CPT codes in the 91000 series that will allow
gastroenterologists to be reimbursed for interpreting and providing VC
services, as well as developing specialized training and training
requirements for those interested in performing VC interpretation. In
an effort to make good on its promise, the AGA published a set of
guidelines in 2007 listing the minimum requirements that a
gastroenterologist must satisfy in order to become certified to read VC
examinations.[8]
Battle Lines are Drawn
Currently
the Centers for Medicare and Medicaid Services (CMS) approve
reimbursement for VC only when it follows a failed "diagnostic"
colonoscopy, not a failed "screening" colonoscopy (Figure 2).[9]
Following the inclusion of VC in the American Cancer Society's
screening guidelines, CMS launched a National Coverage Analysis for
Screening Computed Tomography Colonography for Colorectal Cancer
(CAG-00396N) in May 2008. This seeks to expand reimbursement for
screening indications. The final report of this analysis is due in
February 2009.[10] Expanded reimbursement could have a huge
impact on increasing screening and reducing CRC deaths, but it could
also have substantial economic consequences for CMS and taxpayers. A
public comment period held May-June 2008 drew responses from many
individuals and organizations, including the ACR and the AGA. Of
course, the ACR is in favor of expanded reimbursement, but the AGA
stated that it would support VC only if certain conditions were met,[11] including:
1. Reporting of
ALL polyps (which is contradictory to the ACR Practice Guideline for
the Performance of CTC in Adults that states reporting of polyps <5
mm is not recommended because of the low incidence of those lesions
having malignant potential);[12]
2. Allowing patients in consultation with their physician to determine whether or not to remove those polyps; and
3.
Enacting a coverage policy that would encourage rapid follow-up
procedures (ie, colonoscopy) and that correspondingly would not create
a disincentive for physicians (ie, gastroenterologists) who refer those
procedures.
Reading between the lines, if such conditions are
approved by CMS, then the gastroenterologists will have an unrestrained
ability to perform colonoscopy on any little lump or bump that they
might discover if they or their clinical assistant should be allowed to
read VC exams. It is also the position of many prominent
gastroenterologists to create a split-fee arrangement with radiologists
so that radiologists will be relegated to reading only the extracolonic
portions of a CT scan for a small portion of the professional fee, and,
if radiologists refuse to participate, then they will outsource
radiology services, even to foreign providers![13]
Dispelling Popular Myths
Gastroenterologists frequently try to discredit VC with the following myths:
1. Colonoscopy is the "gold standard."
There are no published studies to validate this claim. In fact, studies
comparing back-to-back colonoscopies on the same patients have reported
OC miss rates of 22% for polyps, even in the hands of expert
endoscopists.[14] Studies such as Pickhardt's[15]
landmark VC study have shown VC to outperform OC. Finally, the accuracy
of screening colonoscopy has been shown to be dependent on how much
time a gastroenterologist spends performing the examination.[16]
2. If VC finds a polyp, then colonoscopy is needed for polyp removal, so why not undergo colonoscopy in the first place?
The vast majority of polyps are benign, hyperplastic polyps, and <5%
of the asymptomatic screening population has a significant adenomatous
polyp.[5] Hence, if OC is the primary screening method, then
>95% of the asymptomatic population would under go OC unnecessarily
with its inherent risks of bowel perforation and anesthesia.
3. The radiation dose associated with VC is prohibitive.
Radiation dose is a valid concern, but researchers are striving to
mitigate this risk by using low-dose techniques, even as low as 10 mAs
(compared with a conventional CT scan that might use a dose of 200 mAs).[17]
Hence, the radiation risk from VC with low-dose techniques can be on
the order of 1 to 2 mSv, which is far below the range that has been
associated with potential cancer and multidetector CT use.[18] Alternatively, VC can be performed using MRI, but the availability of MRI scanners is a temporary hurdle, at least for today.
Actions to Take
Radiologists
are already overworked due to the exponential increase in imaging
studies during the past decade, and as a result, we have become
complacent about the ownership of new technologies. In the meantime,
gastroenterologists are purchasing CT scanners and attending training
programs to get ready for CMS approval of reimbursement for VC
screening.[19] However, if radiologists act quickly and take
certain steps to position ourselves to maintain control of VC, we will
not risk losing this technology, as we have done with cardiac imaging.
Some initiatives include:
1. Taking a stronger, vocal interest in
VC. Radiologists are better trained to read an entire CT examination,
especially when disease crosses organ boundaries to involve both the
colon and adjacent anatomy. We need to establish ourselves as the
imaging experts in order to counter claims that endoscopists and nurse
practitioners are as good as radiologists in reading VC exams.[20]
2.
Beginning a dialogue with community gastroenterologists and primary
care physicians. Radiology practices need to be willing to provide
same-day, on-demand VC services for failed "diagnostic" colonoscopy
examinations in advance of the anticipated reimbursement for screening
VC.
3. Developing practice guidelines for appropriately
working-up extracolonic findings. Perhaps offering immediate but
limited ultrasound evaluation to resolve indeterminate liver and renal
lesions will help to mitigate the gastroenterologists' cry that they
should be the ones performing VC in their offices.
4. Providing
consistent, high-quality reports of VC findings that can be rapidly
delivered to the patient and referring clinician. Utilization of the CT
Colonography Reporting and Data System (C-RADS) and participation in
the ACR's CTC Registry will help to strengthen our position in the
field.[21,22]
5. Challenging any proposals by
gastroenterologists to split the professional fee for reading colonic
and extracolonic portions of a VC CT scan, including legislative
lobbying if necessary. There are many problems with fee-splitting
arrangements, not the least of which is malpractice
liability—radiologists will certainly be held liable when
gastroenterologists fail to make a correct diagnosis if they should be
allowed to interpret only the intraluminal portion of a VC scan.
All is Not Lost, at Least Not Yet
Much
of the rhetoric coming from the gastroenterology community is coming
from a few but very vocal and rabid gastroenterologists. In fact, a
survey of 2400 AGA members regarding their interest in VC resulted in
only 588 responses, of which one third said that they would want to
perform VC, another third said that they would not perform it but would
support their colleagues, and the final third said that
gastroenterologists should not perform VC.[23] In reality,
radiologists and gastroenterologists will need to work together along
with surgeons and oncologists to provide comprehensive CRC screening
and treatment services. If CRC screening really takes off, then there
will not be enough gastroenterologists available in this country to
perform the necessary therapeutic colonoscopies that will be generated.
Although radiologists specializing in VC may eventually become
employees of large, multispecialty clinics specializing in colorectal
disease, it is paramount that the role and expertise of the radiologist
be maintained.
References
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is a Professor of Diagnostic Radiology and the Medical Director of the
Image Processing and Visualization Laboratory, University of Texas M.D.
Anderson Cancer Center, Houston, TX
Dr. Vining discloses that he has received royalties from Wake Forest
University and Bracco, Inc., for virtual colonoscopyrelated products.
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