The Clinical Dilemma of Incidental Findings on the Low-Resolution CT Images from SPECT/CT MPI Studies

Abstract

CE credit: For CE credit, you can access the test for this article, as well as additional JNMT CE tests, online at https://www.snmmilearningcenter.org. Complete the test online no later than September 2019. Your online test will be scored immediately. You may make 3 attempts to pass the test and must answer 80% of the questions correctly to receive 1.0 CEH (Continuing Education Hour) credit. SNMMI members will have their CEH credit added to their VOICE transcript automatically; nonmembers will be able to print out a CE certificate upon successfully completing the test. The online test is free to SNMMI members; nonmembers must pay $15.00 by credit card when logging onto the website to take the test.Incidental findings are common in medical imaging. There is a particularly high prevalence of incidental findings within the thorax, the most frequent being pulmonary nodules. Although pulmonary nodules have the potential to be malignant, most are benign, resulting in a high number of false-positive findings. Low-resolution CT images produced for attenuation correction of SPECT images are essentially a by-product of the imaging process. The high number of false-positive incidental findings detected on these attenuation-correction images causes a reporting dilemma. Early detection of cancer can be beneficial, but falsepositive findings and overdiagnosis can be detrimental to the patient. Attenuation-correction CT images are not of diagnostic quality, and further diagnostic tests are usually necessary for a definitive diagnosis to be reached. Given the high number of falsepositive findings, the psychologic effect on the patient should be considered. This review recommends caution when the findings on attenuation-correction CT images are routinely reported. Medi cal imaging uses a range of modalities that yield both anatomic and functional information (1). Visual correlation of images acquired using separate modalities can provide more information than images from a single modality alone, though there is an inevitable risk of misregistration between images that have been acquired during different imaging sessions. The development of hybrid imaging has led to the integration of two modalities in one machine, allowing coregistration of images that have been acquired in a single session (1,2). This allows direct correlation of anatomic and functional information, increasing sensitivity and specificity while adding clarity to indeterminate cases (3). SPECT/CT offers an excellent example of hybrid imaging, combining the functional ability of SPECT with the anatomic ability of CT.The strength of SPECT lies in gaining pathophysiologic detail in a minimally invasive way (4). Pathologic processes can be identified by uptake of radiopharmaceuticals, but the precise location is often difficult to ascertain because of low image resolution and a lack of anatomic landmarks. Moreover, uptake on some scans is often nonspecific, revealing abnormalities but not their specific cause. CT can provide a useful means of localization, also enabl...

Chest CT versus RT-PCR for the Detection of COVID-19: Systematic Review and Meta-analysis of Comparative Studies

“…Firstly, they are best avoided during pregnancy due to the excessive radiation and risk of harming the foetus [26]. In addition, over-scanning patients with suspected COVID-19 can increase the risk of incidental imaging findings and an unnecessary financial burden on the healthcare system [27]. Furthermore, the use of CT-scans for suspected cases is not practical since SARS-CoV-2 has a relatively high transmission rate; each CT machine needs to be sterilised after use, which can waste time and resources as well as overworking the radiology department in times of need and hence may result in delayed reporting of other potentially lifethreatening conditions.…”

INCIDENTAL FINDINGS OF MALIGNANCY OF THE CHEST BY SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY MYOCARDIAL PERFUSION – One YEAR FOLLOW-UP REPORT.

“…The IF on CTAC during SPECT-CT MPI are frequent, but clinically significant ones are relatively infrequent. [3][4][5] The images obtained by low-dose, low resolution CTAC are adequate for the purpose for which they have been acquired (i.e., anatomical correction and artifact attenuation during cardiac MPI), but are not considered to be diagnostic quality. Despite the limitations of its quality, CTAC would detect pulmonary nodules/mass of certain sizes, as well as other abnormalities in the chest when reviewed.…”

“…However, CTAC images often reveal incidental findings (IF); some of them are of clinical significance. [3][4][5] Previously, we reported a series of six cases of lung/hilar malignancy detected by CTAC during SPECT-CT MPI. 6 In that report, a total of 73/1,098 (6.6%) patients were found to have significant IF of the chest that required further evaluation at the time of SPECT-CT MPI and 6/1,098 (0.55%) patients were found to have pulmonary/ hilar malignancy.…”

Primary Thoracic Cancers Incidentally Detected on CT Attenuation Correction Images During Myocardial Perfusion Scintigraphy

“…The inferior resolution renders it difficult to characterize any incidental lesions as does the absence of intravenous contrast. The images are also limited in the anatomic area they cover and more susceptible to artefact compared to standard diagnostic CT. 3 Conversely, a considerable number of incidental findings can be identified on the CT attenuation correction (CTAC) images which may be of clinical significance.…”

“…cause a clinical dilemma with the most recent and largest review counter-intuitively advising against their routine reporting. 3,9 Case Series…”