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Commentary |
1 Department of Radiology, University of Alabama at Birmingham, 619 S 19th St., N348, Birmingham, AL 35249.
Received January 7, 2008; accepted after revision January 10, 2008.
Address correspondence to L. L. Berland
(lberland{at}gmail.com).
Keywords: anatomy • body CT • diagnosis
I'm looking through you, you're not the same. from Rubber Soul by John Lennon and Paul McCartney
Although they can be read as a hackneyed pun about radiology, these Beatles lyrics carry more substance pertaining to a review of the origins of CT. It is lost to history whether these words helped to inspire the executives of Electric and Musical Industries (EMI) to direct surplus earnings from Beatles record sales toward revolutionizing the way radiologists "look through you." Regardless, EMI's financial support of the research of Godfrey N. Hounsfield (who had been an EMI employee since 1951), made possible by the Beatles, did lead to the first prototype CT scanner in 1967 and the first clinical "EMI scanner" in 1971 [1].
Scarcely 3 years later, the revolutionary concept of CT had already evolved into EMI's first whole-body scanner, also designed by Hounsfield. By 1975, Patrick Sheedy and his colleagues at the Mayo Clinic and Robert Stanley (Editor Emeritus of this journal) and his colleagues at Washington University in St. Louis had begun to use this scanner, leading them to write the first comprehensive articles describing large series of primarily body CT examinations. These articles were printed in the July 1976 issue of this journal and were titled: "Computed Tomography of the Body: Initial Clinical Trial with the EMI Prototype" [2] and "Computed Tomography of the Body: Early Trends in Application and Accuracy of the Method" [3]. Both of these articles qualify among the 100 most-referenced articles in the AJR [4].
The explosive arrival of CT was as swiftly embraced as had been Roentgen's discovery of the X-ray, noted Ter-Pogossian [5] in his introductory editorial for that 1976 issue: "The acceptance of CT by the radiologic community has been immediate, unreserved, and overwhelming, even without well documented proof of its clinical usefulness." Ter-Pogossian also observed that "more than a dozen other companies have rapidly turned their interests to this field" [5].
The startling early images from EMI CT scanners led to both my personal consternation and my excitement as I came to regret foolishly complaining about having to learn useless cross-sectional anatomy as a first-year medical student. It quickly became apparent that the enthusiasm engendered by the new scanners helped to entice a new generation of medical students, like me, into the career of radiology.
Yet, considerable resistance to the dis semination of CT occurred in these early years. Government agencies instituted stringent "certificate of need" constraints, fearing the adoption of an expensive, unproven technique. Many seasoned clinicians could not accept that CT diagnosis could surpass their own physical diagnosis. Also, some radiologists were intimidated by an unfamiliar, complex new technology and by the need to learn new techniques, anatomy, and diagnostic criteria. Therefore, such forces prevented even more rapid growth for CT. Yet, examinations were already increasing inexorably to a rate of 3,000,000 per year by 1980 [6].
Up to the time of the publication of these articles, less than a handful of prior reports of the use of CT for the body had been published [7–10]. Although among the most frequently cited articles from the AJR and representing appreciable series of cases, the Sheedy et al. [2] description of 400 cases and Stanley et al. [3] analysis of 275 cases do not represent transcendent, rigorous models of scientific in quiry. The studies were prospective; how ever, they were not randomized or controlled. The proof of clinical diagnoses was spotty, technical protocols varied widely, the patient populations were heterogeneous, and there were few examinations of any specific organ system or disease state. By modern standards, most of the images ("pictures" as termed by Sir Hounsfield him self [11]) would be considered nearly non diagnostic [2] (Fig. 1). Finally, could we see such articles today without statements of institution al review board approval and patient consent?
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The authors [2, 3] revealed findings of numerous conditions for which CT has become the primary or secondary method of evaluating the abdomen and pelvis, including primary liver cancer, liver metastases, liver abscesses and cysts, biliary dilation, pancreatic cancer, mild and severe acute pancreatitis, pseudocysts, chronic calcific pancreatitis, acute pyelonephritis, renal infarction, polycystic kidney disease, renal cysts, renal carcinoma (including inferior vena cava invasion), angiomyolipomas, hydro nephrosis, retroperitoneal adenopathy, trans itional cell carcinoma of the bladder, cysts, and solid pelvic masses.
In these articles, the authors accurately predicted that CT might become the best method of evaluating myriad conditions within the abdomen and pelvis. For example, we might now consider the following quaintly understated: "As the validity of CT diagnosis becomes established, the need to percutaneously aspirate renal cysts or perform arteriography for indeterminate renal masses will diminish" [3]. In addition to recording and depicting the findings of many common conditions [3] (Fig. 2), these articles also describe the value of IV and oral contrast materials: "...the addition of dilute contrast medium orally helped differentiate the stomach and duodenum, which frequently adhere to the pancreatic neoplasm..." [2].
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Not all of the conclusions were accurately prophetic. Sheedy et al. [2] predicted, "We doubt that CT will be useful in the diagnosis of diseases involving the stomach, duodenum, small intestine, or colon." Similarly, Stanley et al. [3] stated, "In the thorax...CT scans rarely surpass the diagnostic accuracy of conventional radiologic studies." However, given the number of specific cases in which chest CT was useful, this conclusion is curious: "In one patient with intrathoracic malignancy, the extent of the lesion demonstrated on the CT scan aided the referring surgeon in a decision to substitute radiation therapy for resection" [3]. The authors also reported finding numerous other conditions not seen on conventional radio graphy. Given the tendency of early reports of new techniques to be overly enthusiastic, one wonders if the authors were attempting to find matters about which to be overtly pessimistic so as to sound more credible.
An interesting omission common to most discussions of CT until the current decade is discussion of radiation exposure. Except for one brief allusion in the Sheedy et al. study [2], that was the case in the articles discussed here. It was hardly anticipated in its infancy that the new test would lead to the estimated 62,000,000 examinations per year currently performed in the United States alone [6]. Who might have expected then that CT would become responsible for about two thirds of medical radiation exposure [6]? EMI had originally projected a worldwide need for about 25 machines [1]. However, interestingly, along with the recognized benefits of this early validation of the clinical value of CT technology, some of the potential abuses were already being seen: "Situations are developing in which nonradiologic physicians are installing CT devices in their offices" [5].
Despite the flaws, the imprint of this early work on the history of radiology and medicine is unquestionable. By communicating these results to the radiology and medical communities, these reports exemplified the best of clinical observational analysis. They furnished permission to clinically apply cross-sectional axial anatomic imaging to the body.
The deluge of information detailed by these and other articles of the time stands as a well-appreciated landmark in the metamorphosis of radiology. By these articles, Sheedy, Stanley, and their colleagues transformed medical diagnosis and treatment and helped to launch a worldwide, multibillion dollar medical imaging industry. We thank these authors, other authors of similar ground breaking articles, Sir Godfrey Hounsfield, and the Beatles for their crucial contributions to the genesis of a new way of "looking through you" with body CT. We are indeed "not the same" because of them.
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