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Centennial Article |
1 Department of Radiology, Duke University Medical Center, Box 3808, Durham, NC 27710.
Received March 20, 2006; accepted after revision March 24, 2006.
Each month the American Journal of Roentgenology will republish
online one of the 100 most-cited articles from its first century. A
corresponding commentary in the print journal by a contemporary radiologist
will provide a current perspective. For a full list of these articles, see
page 3 of the January
2006 issue of the AJR or go to
www.ajronline.org.
Keywords: adenoma • neuroimaging • pituitary gland • prolactin
In an era in which cross-sectional studies have replaced conventional radiography as the preferred imaging technique for diagnosis of most diseases, it can be easy to lose sight of the difficulties encountered by radiologists before the development of sonography, CT, and MRI. The problem lies in the fact that in many instances, little information can be obtained from X-ray-based techniques (e.g., radiography and tomography) regarding the presence of disease in any organ. For example, one can infer only certain features about the liver, such as size and mass effect on other viscera and hollow organs, from abdominal radiographs. Use of a contrast agent, as during angiography, gives an added dimension for understanding through depiction of some types of abnormalities within the organ, but the result still is far from ideal.
Imagine the challenge in attempting to diagnose disease in a very small organ (the pituitary gland) situated within a small bone compartment (the sella turcica) housed deep within the base of the skull. This problem was faced by Vezina and Sutton in their 1974 article "Prolactin-Secreting Pituitary Microadenomas" [1]. The study population was a group of 20 patients seen in a fertility clinic who were found to have amenorrhea and galactorrhea, an increased serum prolactin level, and abnormalities on sellar tomography suggestive of a pituitary neoplasm. The imaging options available at that time for preoperative diagnosis of a pituitary neoplasm were limited and basically consisted of radiography, pneumoencephalography, tomography, and angiography. Because microadenomas are small and do not cause substantial deformation of the pituitary gland, pneumoencephalography (alone or in association with tomography) would not be expected to be of value in identification of these tumors, and angiography is not helpful. An article [2] on angiography of pituitary neoplasms published the same year as Vezina and Sutton's article showed macroadenomas (initially detectable by the presence of an enlarged sella on conventional radiographs) but did not report identification of microadenomas. Examination of the volume and morphologic features of the sella on conventional radiographs is fraught with difficulty. In an earlier article, Di Chiro and Nelson had provided normal volumetric measurements of the sella [3]. Like Di Chiro and Nelson, Vezina and Sutton faced the issue that the volume of the sella may not reflect the volume of sellar contents or, stated differently, that the size of the container may not adequately reflect the size of its contents [4].
Rather than predicting pituitary gland disease on the basis of the size of the sella, Vezina and Sutton used tomography to depict abnormalities of sellar structure. Specifically, the investigators identified localized bulging and depressions of the sellar floor and thinning or blistering of the sellar walls to infer the presence of pituitary macroadenomas. The authors emphasized the importance of lateralization of the bulging of the sella as an important criterion in making the diagnosis. Vezina and Sutton were thus able to correctly identify a pituitary microadenoma preoperatively in all 20 patients, of whom 14 had normal sellar size.
The difficulties inherent in this task are evident to anyone with experience in the use of MRI to detect pituitary microadenomas. To place the article by Vezina and Sutton in context, the state of the art reflected in contemporary textbooks and articles is worth reviewing. A textbook published the same year as Vezina and Sutton's article emphasized the importance of evaluating the anterior part of the third ventricle, the chiasmatic cistern, and the interpeduncular cistern on pneumoencephalography in the diagnosis of sellar lesions but did not mention deformity of the outlines of the sella [5]. Decker and Backmund's [6] textbook of pediatric neuroradiology, published 1 year after Vezina and Sutton's article, showed only normal anatomic variants of the sella turcica on radiographs and pneumoencephalographs without discussing tumors in the region of the pituitary fossa.
A review of the major American radiology journals on the topic of pituitary abnormalities centering on the 5-year period (1972-1976) surrounding the publication of Vezina and Sutton's article conducted in an attempt to understand the state of the art immediately after publication further shows the extent to which Vezina and Sutton were ahead of their contemporaries. A year after publication of Vezina and Sutton's article, one can find a publication on polytomoencephalography of the optic chiasm depicting subtle suprasellar extension of a chromophobe adenoma [7]. I was not able to find evidence of publication of any large series of microadenomas rivaling that of Vezina and Sutton in the ensuing few years. Thus the article by Vezina and Sutton stands as a landmark not only in terms of subtlety of diagnosis but also in terms of primacy of description of the findings.
It would take the development of CT for a superior method to that reported by Vezina and Sutton to become available. In an early article on CT of the brain, the authors correctly noted that "there will be a significant decrease in utilization of pneumoencephalography...in the future" [8]. One of the first articles on CT of sellar masses appeared in 1976. The authors stated "within the past two years, CT has displaced angiography and pneumoencephalography as the method of choice for the initial evaluation of suspected suprasellar tumors" [9]. Nonetheless, the article emphasized the use of CT for diagnosis of suprasellar masses, such as macroadenomas. The reliability of CT for diagnosis of microadenomas, the focus of Vezina and Sutton in 1974, was not discussed. In 1978, one of the first CT articles describing the appearance of microadenomas was published [10]. This article was followed a year later by one of the first systematic reviews of the CT appearance of pituitary adenomas [11]. Thus the article by Vezina and Sutton is notable for its advancement of neuroradiologic technique for depiction of pituitary lesions that previously could not be reliably diagnosed. The availability of CT within a decade of its publication limits the length of time during which the article influenced neuroradiologists but does not diminish the importance of the article at the time of publication or detract from the diagnostic acumen exhibited by the authors.
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