Detection of unknown primary tumor in patients presented with brain metastasis by F-18 fluorodeoxyglucose positron emission tomography/computed tomography

A transformer-based deep-learning approach for classifying brain metastases into primary organ sites using clinical whole-brain MRI images

Treatment decisions for brain metastatic disease rely on knowledge of the primary organ site and are currently made with biopsy and histology. Here, we develop a deep-learning approach for accurate non-invasive digital histology with whole-brain magnetic resonance imaging (MRI) data. Contrast-enhanced T1-weighted and fast spoiled gradient echo brain MRI exams (n = 1,582) were preprocessed and input to the proposed deep-learning workflow for tumor segmentation, modality transfer, and primary site classification into one of five classes. Tenfold cross-validation generated an overall area under the receiver operating characteristic curve (AUC) of 0.878 (95% confidence interval [CI]: 0.873,0.883). These data establish that whole-brain imaging features are discriminative enough to allow accurate diagnosis of the primary organ site of malignancy. Our end-to-end deep radiomic approach has great potential for classifying metastatic tumor types from whole-brain MRI images. Further refinement may offer an invaluable clinical tool to expedite primary cancer site identification for precision treatment and improved outcomes.

Effect of Whole-body [18F]Fluoro-2-deoxy-2-d-glucose Positron Emission Tomography in Patients with Suspected Brain Metastasis

Background and Purpose [18F]Fluoro-2-deoxy-2-d-glucose (FDG) positron emission tomography/computed tomography (PET/CT) has a promising role in the workup and management of carcinoma of unknown primary (CUP). We have evaluated the effect of whole-body FDG PET/CT in assessing the patients presented with suspected brain metastasis (CUP-BM) on brain magnetic resonance imaging (MRI) or computed tomography (CT).

Materials and Methods This retrospective study included FDG PET/CT of 50 patients (24 males, mean: 58 ± 12.2 years old) with a CUP-BM diagnosis based on MRI and CT imaging. The final diagnosis of primary brain neoplasm (BP) or brain metastases (BM) was based on FDG PET/CT findings and/or histopathology (HPE).

Results On FDG PET/CT, 52% (26/50) of patients did not have any systemic lesion apart from a brain lesion. Out of these, 50% (13/26) had HPE confirmation of primary brain neoplasm (BP). FDG PET/CT identified multiple systemic lesions apart from brain lesions in the remaining 48% (24/50) of patients. They were categorized as the brain metastases (BM) group. The primary lesions were located in the lungs (n = 20), kidneys (n = 1), prostate (n = 1), esophagus (n = 1), and tongue (n = 1).

Conclusion FDG PET/CT could suggest a diagnosis of BM based on the presence of systemic lesions. It also provides an easily accessible peripheral site for biopsy and systemic disease burden in a single scan. FDG PET/CT's up-front use in suspected CUP-BM on CT and/or MRI could differentiate the BM from BP in most cases and avoid brain biopsy in the BM group.

The Chemical Scaffold of Theranostic Radiopharmaceuticals: Radionuclide, Bifunctional Chelator, and Pharmacokinetics Modifying Linker

Therapeutic radiopharmaceuticals have been researched extensively in the last decade as a result of the growing research interest in personalized medicine to improve diagnostic accuracy and intensify intensive therapy while limiting side effects. Radiometal-based drugs are of substantial interest because of their greater versatility for clinical translation compared to non-metal radionuclides. This paper comprehensively discusses various components commonly used as chemical scaffolds to build radiopharmaceutical agents, i.e., radionuclides, pharmacokinetic-modifying linkers, and chelators, whose characteristics are explained and can be used as a guide for the researcher.

What Does PET Imaging Bring to Neuro-Oncology in 2022? A Review

Simple Summary

Positron emission tomography (PET) imaging is increasingly used to supplement MRI in the management of patient with brain tumors. In this article, we provide a review of the current place and perspectives of PET imaging for the diagnosis and follow-up of from primary brain tumors such as gliomas, meningiomas and central nervous system lymphomas, as well as brain metastases. Different PET radiotracers targeting different biological processes are used to accurately depict these brain tumors and provide unique metabolic and biologic information. Radiolabeled amino acids such as [¹⁸F]FDOPA or [¹⁸F]FET are used for imaging of gliomas while both [¹⁸F]FDG and amino acids can be used for brain metastases. Meningiomas can be seen with a high contrast using radiolabeled ligands of somatostatin receptors, which they usually carry. Unconventional tracers that allow the study of other biological processes such as cell proliferation, hypoxia, or neo-angiogenesis are currently being studied for brain tumors imaging.

Abstract

PET imaging is being increasingly used to supplement MRI in the clinical management of brain tumors. The main radiotracers implemented in clinical practice include [¹⁸F]FDG, radiolabeled amino acids ([¹¹C]MET, [¹⁸F]FDOPA, [¹⁸F]FET) and [⁶⁸Ga]Ga-DOTA-SSTR, targeting glucose metabolism, L-amino-acid transport and somatostatin receptors expression, respectively. This review aims at addressing the current place and perspectives of brain PET imaging for patients who suffer from primary or secondary brain tumors, at diagnosis and during follow-up. A special focus is given to the following: radiolabeled amino acids PET imaging for tumor characterization and follow-up in gliomas; the role of amino acid PET and [¹⁸F]FDG PET for detecting brain metastases recurrence; [⁶⁸Ga]Ga-DOTA-SSTR PET for guiding treatment in meningioma and particularly before targeted radiotherapy.

Diagnostic efficiency of PET/CT in patients with cancer of unknown primary with brain metastasis as initial manifestation and its impact on overall survival

Background

Carcinoma of unknown primary (CUP) is a diagnostic and therapeutic challenge; correct diagnostic approach results in better outcomes in patients with brain metastasis. Whole body 18 F-FDG PET/CT is a helpful modality to detect the origin of primary tumor and assess metastasis in the rest of the body. We assessed the value of PET/CT in detection of unknown primary in 39 patients with brain metastases as initial presentation and detected its impact on their overall survival.

Results

PET/CT could correctly detected the primary tumor in 49% of patients which occurred mainly in the lung, 63% of patients had additional extracerebral metastatic sites mostly in lymph nodes. Specificity, sensitivity, and accuracy of PET/CT in CUP patients were 95%, 79%, and 87%, respectively. No significant difference was noticed in estimated overall survival time between patients with an identified primary tumor and patients with unidentified primary tumor.

Conclusion

PET–CT was a helpful non-invasive imaging modality in detecting primary in CUP patients with metastatic brain lesion. It helped in the diagnosis of unexpected extracerebral metastatic lesions. However, the identification of the primary tumor by PET/CT has no significant prognostic effect on patient overall survival.

Brain Metastasis from Unknown Primary Tumour: Moving from Old Retrospective Studies to Clinical Trials on Targeted Agents

Simple Summary

Brain metastases (BMs) are the most common intracranial tumours in adults and occur up to 3–10 times more frequently than primary brain tumours. In up to 15% of patients with BM, the primary tumour cannot be identified. These cases are known as BM of cancer of unknown primary (CUP) (BM-CUP). The understanding of BM-CUP, despite its relative frequency and unfavourable outcome, is still incomplete and clear indications on management are missing. The aim of this review is to summarize current evidence on the diagnosis and treatment of BM-CUP.

Abstract

Brain metastases (BMs) are the most common intracranial tumours in adults and occur up to 3–10 times more frequently than primary brain tumours. BMs may be the cause of the neurological presenting symptoms in patients with otherwise previously undiagnosed cancer. In up to 15% of patients with BMs, the primary tumour cannot be identified. These cases are known as BM of cancer of unknown primary (CUP) (BM-CUP). CUP has an early and aggressive metastatic spread, poor response to chemotherapy, and poor prognosis. The pathogenesis of CUP seems to be characterized by a specific underlying pro-metastatic signature. The understanding of BM-CUP, despite its relative frequency and unfavourable outcome, is still incomplete and clear indications on management are missing. Advances in diagnostic tools, molecular characterization, and target therapy have shifted the paradigm in the approach to metastasis from CUP: while earlier studies stressed the importance of finding the primary tumour and deciding on treatment based on the primary diagnosis, most recent studies focus on the importance of identifying targetable molecular markers in the metastasis itself. The aim of this review is to summarize current evidence on BM-CUP, from the diagnosis and pathogenesis to the treatment, with a focus on available studies and ongoing clinical trials.

Clinical Impact of F-18 FDG PET-CT on Biopsy Site Selection in Patients with Suspected Bone Metastasis of Unknown Primary Site

Purpose

We investigated the clinical role of F-18 fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) in the identification of the primary site and the selection of the optimal biopsy site in patients with suspected bone metastasis of unknown primary site.

Methods

The patients with suspected bone metastasis who underwent PET-CT for evaluation of primary site were enrolled in this study. The primary sites were identified by the histopathologic or imaging studies and were classified according to the FDG uptake positivity of the primary site. To evaluate the guiding capability of PET-CT in biopsy site selection, we statistically analyzed whether the biopsy site could be affected according to the presence of extra-skeletal FDG uptake.

Results

Among 74 enrolled patients, 51 patients had a metastatic bone disease. The primary site was identified in 48 of 51 patients (94.1%). Forty-six patients were eligible to test the association of clinical choice of biopsy site with PET positivity of extra-skeletal lesion. The extra-skeletal biopsies were done in 42 out of 43 patients with positive extra-skeletal uptake lesions. Bone biopsies were inevitably performed in the other three patients without extra-skeletal uptake lesions. The association came out to be significant (Fisher's exact test, P < 0.001).

Conclusion

F-18 FDG PET-CT significantly contributed not only to identify the primary site but also to suggest optimal biopsy sites in patients with suspected bone metastasis.

Diagnostic Value of CT of Chest, Abdomen, and Pelvis in Patients With Solitary and Multiple Brain Lesions

OBJECTIVE. A common goal in patients with newly discovered brain lesions is to determine if the lesions are primary malignant brain neoplasms, metastases, or benign entities. Such patients often undergo CT of the chest, abdomen, and pelvis (CT CAP) to identify a primary neoplasm that may have metastasized to the brain. The aim of this study is to determine the frequency of finding a primary cancer on CT CAP. MATERIALS AND METHODS. A large academic hospital imaging database was searched for cases of new intracranial lesions with subsequent CT CAP performed for metastatic workup. The frequency of primary neoplasms diagnosed in the chest versus abdominal and pelvic portions of CT scans was determined in patients with newly identified intraaxial and extraaxial brain lesions. Lesion characteristics were recorded including size, number, and the presence of enhancement and hemorrhage. Ancillary signs of an abdominopelvic neoplasm were also recorded. RESULTS. A total of 227 of 287 (79%) cases of newly discovered intracranial lesions were malignant (primary or metastatic) and 60 (21%) were benign. Of the 227 malignant cases, 136 (60%) were primary brain neoplasms and 91 (40%) were brain metastases, and 68 of the 91 (75%) lung primary. Chest CT (CTC) identified a primary neoplasm in 65 of 287 (23%) cases; 63 of those 65 (96%) neoplasms arose in the lungs. CT of the abdomen and pelvis (CTAP) identified a primary neoplasm in only 3 of 287 (1%) cases. In 26 cases in which the intracranial lesions did not enhance, only one was metastatic. CONCLUSION. In patients with newly discovered brain lesions, CTC is warranted, but CTAP is unlikely to be useful in patients without ancillary signs of abdominopelvic neoplasm.

The spectrum of malignancies presenting with neurological manifestations: A prospective observational study

Introduction

A neurological consultation is needed in nearly 45% of patients suffering from cancer. The present study was planned to evaluate the clinical, radiological and histopathological spectrum of patients with an underlying malignancy and presenting with a neurological complaint.

Materials and Methods

We prospectively evaluated all patients provisionally diagnosed either with a primary or secondary malignancy of the brain on the basis of clinical, radiological and/or histopathological features.

Results

A total of 155 patients were enrolled from a total of 4893 admissions done from January 2015 to July 2016. The common presenting symptoms were headache, back pain and paraparesis. Around 26% of patients presented with an altered sensorium, 19.4% with seizures and 21% had at least one cranial nerve involvement. The most common site of involvement was the brain noted in 49.7% of patients. Primary malignancies constituted 78 cases (50.7%) while secondary malignancies included 77 cases (49.3%). Magnetic resonance imaging (MRI) revealed 92 (59.4%) intra-axial lesions and 59 (38.1%) extra-axial lesions, with five cases having both. The most common diagnoses were intra-cerebral metastases and glioblastoma (intra-axial), and vertebral metastases and meningioma (extra-axial). Histopathological confirmation was obtained in 59 patients (38.1%) with 12 primary and 47 secondary lesions. Ten (6.45%) patients had an unknown primary with secondary metastases. The three most common histopathologically confirmed diagnoses were adenocarcinoma lung, plasma cell dyscrasia and adenocarcinoma prostate.

Conclusion

Primary neurological consultations with an unknown primary are common hence a high index of suspicion can prevent an inadvertent delay in the diagnosis and appropriate treatment of a malignant lesion. Developing a neuro-oncology register may help us in gaining more insight into such situations.

Advances in the management of brain metastases from cancer of unknown primary

Cancer of unknown primary accounts for 3-5% of all cancers for which an adequate investigation does not identify the primary tumor. The particular subset of brain metastasis in cancer of unknown primary (BMCUP) is a clinical challenge that lacks standardized diagnostic and therapeutic options. It is diagnosed predominantly in male patients in the sixth decade of age with complaints of headache, neurological dysfunction, cognitive and behavioral disturbances and seizures. The therapeutic approach to patients with BMCUP relies on local control and systemic treatment. Surgery or stereotactic radiosurgery and/or whole brain radiation therapy seems to be the cornerstone of the treatment approach to BMCUP. Systemic therapy remains essential as cancers of unknown primary are conceptually metastatic tumors. The benefits of chemotherapy were disappointing whereas those of targeted therapies and immune checkpoint inhibitors remain to be evaluated. In this Review, we address the advances in the diagnosis and treatment of BMCUP.