Original ArticleThe Utility of Whole Body Imaging in the Evaluation of Solitary Brain Tumors
Introduction
Of the patients with a systemic malignancy, 20%–40% will develop brain metastases,1 and differentiation between primary solitary brain tumors and single brain metastases presents an important clinical challenge in patients with a newly diagnosed brain tumor but no history of systemic malignancy. Distinguishing between a primary neoplasm and metastatic disease in these patients solely by cranial imaging can be difficult. The similar radiologic appearances can make it challenging in some cases to rely on magnetic resonance imaging (MRI) alone.2 Although occasionally challenging, differentiating between primary and metastatic brain tumors is essential in determining the safest course of treatment, because each type of tumor has vastly different approaches regarding the therapeutic decisions and surgical interventions available.3
Previous reports on differentiating metastatic disease from primary neoplasms have focused on advanced MRI, including the use of relative cerebral blood volume (rCBV), dynamic susceptibility contrast (DSC) perfusion imaging, and diffusion tensor imaging (DTI). Each of these imaging modalities have limitations. Differences in the tumoral and peritumoral cerebral blood volume values can help in differentiating between glioblastomas and metastases. However, this method might be more accurate in grading than in differentiating the tumors.4, 5 Using DSC perfusion imaging has demonstrated differences in the average peak height and signal intensity recovery between glioblastomas and metastases.2, 4 Another study has shown that DTI can improve the diagnostic differentiation by using classification models based on fractional anisotropy and mean diffusivity.6
Direct tissue sampling in the form of biopsy or surgical resection is required for definitive pathologic and immunologic analysis. Noninvasive whole body computed tomography (CT) imaging might provide another diagnostic tool in the differentiation of solitary brain tumors and warrants further investigation. Intuition has suggested that the presence of neoplasms on CT screening of the chest, abdomen, or pelvis (CAP) would indicate that the brain lesion represents metastatic disease. However, a paucity of data is available to support this idea. The aim of the present study was to determine the clinical utility of using screening whole body CT to correctly identify intracranial pathology in patients with solitary brain lesions.
Section snippets
Methods
A prospectively maintained surgical database for a large quaternary care academic institution was retrospectively reviewed for all patients who had undergone craniotomy for a new diagnosis of an enhancing solitary brain tumor at our facility from January 2011 to January 2016. Whole body CT scans were performed as a part of the preoperative evaluation for patients whose solitary tumors were diagnostically uncertain and/or for whom clinical suspicion was present for metastatic disease. Patients
Results
During the 5-year study period, 861 patients had undergone craniotomy for tumor. Of these, 218 patients had met inclusion criteria and constituted the study cohort (Figure 1). Of the 218 patients, 108 were men (49.5%) and 110 were women (50.5%). The mean age at presentation was 64.1 years for the 218 patients. The mean tumor diameter was 4.0 cm, as assessed on contrast-enhanced imaging studies. All the patients had undergone preoperative whole body contrast-enhanced CT scanning to detect
Discussion
The diagnosis of solitary brain tumors is often difficult using MRI alone, because primary and metastatic tumors can demonstrate similar radiologic characteristics. For example, gliomas and metastases will have similar rates of hypointense borders on T2-weighted MRI and similar rates of heterogeneous central necrosis.1, 7 A patient's history of cancer can help aid in the diagnosis, because 80% of metastatic brain tumors will be discovered after the initial primary cancer has been diagnosed.8
Conclusion
Preoperative whole body CT has clinical utility in aiding in the establishment of a differential diagnosis of primary brain tumor versus metastatic lesion. This noninvasive screening test has value in the preoperative patient consultation to explain the benefits of craniotomy for biopsy or resection. The identification of extracranial primary tumors offers alternative and easily accessible sites for biopsy, potentially saving the patient from a cranial procedure. The prognosis and treatment of
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.