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1 From the Department of Radiology, Thomas Jefferson University Hospital, 3390 Gibbon Bldg, 111 S 11th St, Philadelphia, PA 19107. From the 2001 RSNA scientific assembly. Received October 23, 2001; revision requested January 14, 2002; final revision received April 29; accepted May 8. Address correspondence to S.C.W.
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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MATERIALS AND METHODS: Results of 2,500 lumbar spinal 1.5-T MR examinations were reviewed. These included 500 consecutive lumbar spinal MR reports for each of 5 years: 1 year prior to PACS introduction, 1 year during transition to PACS, and 3 consecutive years thereafter. Incidental findings cited in the reports were tabulated, and the frequency, organ system involved, and radiologist recommendations in each case were noted and compared, as were projected expenses based on the Medicare payment scale for recommended follow-up studies. Results of available follow-up studies were also reviewed.
RESULTS: The number of incidental findings increased from 19 before PACS to 31 during transition and 53, 49, and 50 after PACS implementation, which resulted in a maximum increase of 179%. The increase was statistically significant during each post-PACS year. The most common incidental findings involved potential renal, pelvic, hepatic, pulmonary, and lymph node abnormalities. The total number of recommended follow-up studies increased from five before PACS to 15 during transition and 32, 22, and 18 after PACS implementation, with a maximum increase of as much as 540%. Recommended ultrasonographic studies increased the most from two in the pre-PACS year to 11 during transition and 27, 17, and 14 in the 3 post-PACS years. Follow-up expense increased by a mean of 146% after PACS implementation from $4,221 per 1,000 studies in the pre-PACS year to $9,307, $13,426, $10,558, and $8,252 thereafter. Of the 202 incidental findings, four represented occult malignancy, which is an expense of $5,721 per diagnosis.
CONCLUSION: The introduction of PACS into radiology practice for lumbar spinal MR imaging appears to be associated with an increased number of reported incidental findings and recommended follow-up studies.
© RSNA, 2002
Index terms: Economics, medical • Picture archiving and communication system (PACS) • Radiology and radiologists, socioeconomic issues
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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Since localizer images have a large field of view, including anatomic regions outside the region of interest for a specific examination, visualization of structures outside the region of clinical concern may result in more incidental findings. While most studies (1–4) concerning PACS thus far have concentrated on the effect on the radiology department’s productivity and usage, our study concerns the effect of PACS on study interpretation and patient care in terms of incidental findings. Our purpose was to determine the effect of PACS on the reporting of incidental findings outside the area of interest, with a focus on lumbar spinal magnetic resonance (MR) imaging as a prototype.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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All reports were reviewed in their entirety by one author (S.C.W.), not involved in the initial interpretation, who identified incidental findings cited either in the diagnosis section or in the full body of the report. The imaging characteristics of the lesion, organ system involved, and any recommendations for further imaging or follow-up were recorded. For purposes of our study, we defined an incidental finding as any disease suggested outside the region of clinical interest; for the lumbar spine this would include anything other than disease related to the vertebrae, intervertebral discs, neural structures, spinal canal, and paraspinal soft tissues.
For each report in which an incidental finding was noted, one author (S.C.W.) reviewed the full reports of all subsequent imaging and recorded the modality and result of each follow-up study. When available, clinical follow-up results were obtained from inpatient and outpatient chart reviews and our hospital clinical information system.
Since the charges and actual cost of follow-up studies is variable and true cost determination is difficult, we reported the more constant and widely applicable Medicare reimbursement as an estimate of expense to the health care system. The Medicare reimbursement schedule from the year 2000 was applied to all study years to estimate expense of follow-up studies per year and per occult malignancy discovered and to provide a means of comparing relative expenses for each year. We also plotted the number of incidental findings, the number of follow-up studies recommended, and the expense of follow-up studies per year to identify potential trends in the number of incidental findings and expense of follow-up in temporal relation to PACS implementation.
MR Imaging Technique
All images were obtained at 1.5 T (Signa; GE Medical Systems, Milwaukee, Wis) according to our standard protocol for lumbar spinal MR imaging. There were no protocol or equipment alterations throughout the study. Each study included either a coronal or three-plane localizer series with a T1-weighted fast gradient-recalled-echo sequence at 56–150/1–3 (repetition time msec/echo time msec) with a 40-cm field of view, 90° flip angle, 256 x 128 matrix, 6-mm section thickness, and 1-mm intersection gap.
Standard lumbar spinal imaging also included the following pulse sequences: sagittal T1-weighted spin echo (433–417/9–11), sagittal intermediate-weighted fast spin echo (1,800/14–21), sagittal T2-weighted fast spin echo with fat suppression (4,000/84), and transverse fast spin echo (3,017–4,733/23–33). In all sagittal sequences, a 28-cm field of view, 4-mm section thickness, and 1-mm intersection gap were used. In transverse sequences, a 22-cm field of view, 4-mm section thickness, and 1-mm intersection gap were used. For all studies, a body coil was used for the localizer series, and a spinal coil was used for all other sequences.
Statistical Analysis
Statistical analysis was performed to determine whether there were significant differences in the proportion of incidental findings and recommended follow-up studies during the 5 years. Two null hypotheses were tested. (a) The number of incidental findings reported is independent of the year of interpretation (ie, independent of hard-copy or soft-copy interpretation). (b) The number of follow-up studies recommended is independent of hard-copy or soft-copy interpretation. Pairwise comparisons were performed for the pre-PACS index year (1995) and each subsequent year (1997 through 2000), excluding 1996, as this was the installation period for PACS at our institution. For each pairwise comparison, 2 x 2 contingency tables were generated, with the columns indicating the years of interest and the rows indicating the number of incidental findings reported or follow-up studies recommended.
To test the first null hypothesis, cells were populated with the number of reports with incidental findings in one row and the number of reports without incidental findings in the other row. To test the second null hypothesis, cells were populated with the number of reports with follow-up studies recommended in one row and the number of reports without follow-up studies recommended in the other row. The Fisher exact test was applied to each contingency table separately to determine if there were nonrandom associations between the two variables of interest. A P value of less than .05 was considered to indicate a statistically significant difference.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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In the 2nd year of PACS, a 34-year-old pregnant woman was referred for lumbar spinal MR imaging to evaluate back and right hip pain. Coronal localizer images showed an incidental pelvic mass spreading to involve the right ilium (Fig 4). Follow-up dedicated MR imaging of the pelvis and subsequent CT-guided biopsy revealed recurrent cervical carcinoma with regional spread to the right ilium. Two additional cases in the 2nd year of PACS showed incidental renal masses on the MR localizer series. one in a 74-year-old woman and the other in a 71-year-old man. Both were shown at follow-up to be renal cell carcinoma. In the 3rd year of PACS, CT follow-up of hepatic masses (Fig 5) seen on the localizer series revealed metastatic disease in a patient with primary bronchogenic carcinoma.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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Lev et al (6) showed improved detection of acute stroke when interpreting nonenhanced CT scans with a PACS workstation versus with conventional hard-copy images, which is related to the ability to manipulate window and level setting. Authors of other reports show decreased preparation time for radiologists who use PACS for clinical-radiologic conferences (7), increased inpatient and outpatient use of radiologic services (2), and improved image management with fewer lost and unread studies in departments that use PACS (8).
Since the introduction of PACS at our institution, we have changed our mode of interpretation of cross-sectional images from conventional hard-copy images to soft-copy viewing on PACS workstations. In addition to the advantages of PACS described previously, PACS also provides dynamic image control—the ability to manipulate viewing parameters such as window, level, and magnification, to accommodate the reviewer’s preference. PACS also provides a means of archiving, remote viewing, and access for clinician review.
Unlike interpretation of hard-copy studies, interpretation from PACS workstations provides access to all images of each series in an uncropped format; in particular, all localizer images are available, which for lumbar spinal studies includes the majority of the abdomen, pelvis, and lower chest. Prior to PACS at our institution, MR images were cropped to the region of interest, and printed studies included only one or two limited images from the localizer series for purposes of cross-referencing.
Since the introduction of PACS at our institution, we have anecdotally noticed more incidental findings during our interpretations, particularly during lumbar spinal MR imaging, as this is a common examination and anatomically there are many nearby structures and viscera in which incidental findings may be identified. Therefore, we sought to evaluate whether the use of PACS workstations to review cases has affected our detection of incidental findings, and in particular, how often we detect clinically important disease, particularly occult malignancies, during lumbar spinal imaging.
In this study, we showed that the number of incidental findings reported increased significantly by 163% after the implementation of PACS. Along with the increased number of incidental findings, the total number of follow-up studies recommended increased by 540% since these findings are incompletely evaluated on lumbar spinal MR images. Recommendations for follow-up US increased most dramatically—as much as 1,250%—after PACS. Recommendations for follow-up MR examinations were noted after PACS implementation, while recommendations for CT and radiographic follow-up remained relatively stable. This finding was expected. Since most incidental findings on lumbar spinal MR images involve renal and gynecologic abnormalities, US is often the imaging modality of choice.
On the basis of the body part being examined and the anatomy encompassed by the field of view and localizer images, we would expect different types of incidental findings, frequencies, and follow-up recommendations. For example, cervical spinal MR studies may depict findings in the thyroid, brain, lungs, and mediastinum. Also, depending on the MR imager, localizer pulse sequences may vary and have an effect, positive or negative, on the detection of incidental findings.
The most common incidental findings in our study involved renal, gynecologic, and hepatic abnormalities. In the follow-up studies that were available for review, most incidental findings in the lumbar spinal MR studies represented benign processes, such as renal, ovarian, or hepatic cysts and uterine leiomyomas.
In two patients, however, renal US and subsequent CT follow-up for incidental renal lesions revealed renal cell carcinoma. One patient had multiple concomitant medical problems and declined nephrectomy, while the other patient continued to be closely followed up with repeated CT to follow the size of a slowly growing renal cell carcinoma that had reached 2.5 cm at the time of this writing. In a third patient, follow-up US of a possible adnexal mass revealed a cystic ovarian mass, which was shown at surgery to be an ovarian carcinoma.
A fourth patient, who presented with back and hip pain during pregnancy, had recurrent cervical carcinoma. This patient subsequently terminated the pregnancy and after receiving both chemotherapy and radiation therapy has stable local disease without distant metastasis. Diffuse metastatic disease was found at follow-up CT in a patient with bronchogenic carcinoma and hepatic lesions initially identified on the lumbar spinal MR localizer series. Even though most incidental findings represented benign disease, if any disease at all, we have shown the potential for identifying clinically important occult disease (ie, malignancy).
We also evaluated the expense to the health care system for follow-up examinations for incidental findings. The expense of Medicare reimbursement of follow-up imaging recommended increased by a mean of 146% after PACS implementation. In the total of 202 incidental findings and the total of $22,882 Medicare reimbursement for follow-up studies, four cases of occult malignancy were identified at an expense of $5,721 per diagnosis.
Since this expense is based only on follow-up imaging, there are several other potentially substantial costs to both the patient and the health care system. For example, incidental findings may result in additional physician visits, possible laboratory tests, and patient anxiety, all costs that are not included in our expense per diagnosis. Ultimately, patients, physicians, and policy makers will need to evaluate the cost-to-benefit ratio to determine the appropriateness of pursuing incidental findings.
Given the data we obtained at our institution, we will continue with the practice of reviewing all localizer images for incidental findings, reporting those findings to the referring physician, and recommending appropriate follow-up imaging. These lesions are often occult, and further work-up is required, as visceral abnormalities often will not produce signs or symptoms until function is impaired. Authors of another article (9) support the practice of appropriate follow-up recommendations. These authors show that renal cell carcinoma, when identified as an incidental finding, is often at a lower stage, so these patients may have better survival than that for patients in whom the diagnosis was suspected.
Limitations of the study include the retrospective analysis of reports, since we evaluated only incidental findings mentioned in the report. Because we wanted to evaluate this issue in a clinically relevant setting, we believed that reports were a more realistic barometer than would be re-reviewing the actual images from each study. There likely were many more incidental findings that were not identified during initial interpretation and therefore were not included in the report or this study. Also, patients in whom findings at clinical follow-up were not available may have undergone follow-up imaging or procedures elsewhere that were not included in our data. On the basis of these limitations, we likely underestimated expenses.
We did not assess variability in the referring clinicians’ choices in handling radiology results and making recommendations for follow-up of incidental findings. Since the studies were dictated by several radiologists, there may have been variability of interpretation and reporting styles. There were, however, no specific changes in practice policy, MR imaging protocol, or turnover of staff during PACS implementation.
This study was not designed as a cost analysis study, and we did not measure direct cost of follow-up examinations recommended. We used expected Medicare reimbursement as a reference for assessing expense to the health care system. Application of the year 2000 Medicare reimbursement schedule to all study years may have led to overestimation of the expense of imaging in the earlier years, but this method served as a comparison of relative expense between study years.
Finally, since this study represents the effect of PACS at one institution, the results may not be generalizable. Accepting these limitations, we present an initial report to describe the effect of PACS on study interpretation, health care expense, and patient care related to incidental findings.
In summary, the introduction of PACS into radiology practice for lumbar spinal MR imaging appears to be associated with an increased number of incidental findings reported and follow-up studies recommended. The immediate effect may be increased expense to the health care system because of additional examinations, although clinically important occult disease may be identified. Further research may be required to confirm that this effect of PACS on identification of incidental findings is generalizable to other institutions and to measure this effect on non–lumbar spinal examinations.
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FOOTNOTES |
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Author contributions: Guarantors of integrity of entire study, S.C.W., W.B.M.; study concepts, S.C.W., W.B.M., J.A.C., M.E.S.; study design, S.C.W., W.B.M.; literature research, S.C.W., W.B.M., J.A.C.; clinical studies, S.C.W., W.B.M.; data acquisition, S.C.W., W.B.M., H.N.; data analysis/interpretation, S.C.W., W.B.M.; statistical analysis, J.A.C.; manuscript preparation, S.C.W., W.B.M.; manuscript definition of intellectual content, W.B.M., S.C.W., J.A.C.; manuscript editing, revision/review, and final version approval, S.C.W., W.B.M., J.A.C., M.E.S.
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTSDISCUSSIONREFERENCES |
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