Central nervous system lymphoma: characteristic findings on traditional and advanced imaging

Pituitary Stalk Enlargement in Adults

Pathologies involving the pituitary stalk (PS) are generally revealed by the presence of diabetes insipidus. The availability of MRI provides a major diagnostic contribution by enabling the visualization of the site of the culprit lesion, especially when it is small. However, when only an enlarged PS is found, the etiological workup may be difficult, particularly because the biopsy of the stalk is difficult, harmful and often not contributive. The pathological proof of the etiology thus needs to be obtained indirectly. The aim of this article was to provide an accurate review of the literature about PS enlargement in adults describing the differences between the numerous etiologies involved and consequent different diagnostic approaches. The etiological diagnostic procedure begins with the search for possible other lesions suggestive of histiocytosis, sarcoidosis, tuberculosis or other etiologies elsewhere in the body that could be more easily biopsied. We usually perform neck, thorax, abdomen, and pelvis CT scan; positron emission tomography scan; bone scan; or other imaging methods when we suspect generalized lesions. Measurement of serum markers such as human chorionic gonadotropin, alpha-fetoprotein, angiotensin converting enzyme, and IgG4 may also be helpful. Obviously, in the presence of an underlying carcinoma (particularly breast or bronchopulmonary), one must first consider a metastasis located in the PS. In the case of an isolated PS enlargement, simple monitoring, without histological proof, can be proposed (by repeating MRI at 3-6 months) with the hypothesis of a germinoma (particularly in a teenager or a young adult) that, by increasing in size, necessitates a biopsy. In contrast, a spontaneous diminution of the lesion is suggestive of infundibulo-neurohypophysitis. We prefer not to initiate steroid therapy to monitor the spontaneous course when a watch-and-see attitude is preferred. However, in many cases, the etiological diagnosis remains uncertain, requiring either close monitoring of the lesion or, in exceptional situations, trying to obtain definitive pathological evidence by a biopsy, which, unfortunately, is in most cases performed by the transcranial route. If a simple surveillance is chosen, it has to be very prolonged (annual surveillance). Indeed, progression of histiocytosis or germinoma may be delayed.

Effects of HIV on the Tumor Microenvironment

Oncomodulatory viruses can affect the tumor microenvironment (TME) by triggering inflammation, suppressing apoptosis, initiating angiogenesis, altering tumor metabolism, and stimulating tumor cell signaling pathways, leading to tumor growth, proliferation, and invasion. The higher incidence of malignancies among people with HIV (PWH), despite the widespread use of antiretroviral therapy (ART), suggests a more complex relation than HIV-associated immune deregulation. Viral cooperation can have synergistic effect on tumorigenesis. The most relevant oncogenes involved in viral cooperation include the HIV-1-related Tat and Vpu genes, EBV LMP-1 and EBNA-2 genes, and Kaposi's sarcoma herpesvirus (KSHV) KIE2, Rta, and LANA genes. The TME in HIV-related malignancies is highly angiogenic and characterized by high microvessel density compared to sporadic cases. Tat protein, found in patients with HIV infection regardless of their immune status, has been widely implicated in the increased angiogenesis and has been a target of interest for therapeutic strategies. Similarly, HIV-1 matrix protein p17 can be detected in the plasma and tissues of PWH, including those treated with ART. Studies have found that p17 can cause dysregulation of the biological activity of different immune cells, is involved in aberrant angiogenesis, and exhibits an IL8 chemokine activity, activating multiple intracellular signaling pathways, promoting angiogenic responses in endothelial cells, and forming capillary like structures. In addition, several studies have demonstrated difference in the cellular immune components within the TME in patients with or without HIV infection, as well as cases in pre- and post-ART era. In this chapter, we review the existing literature about the role tumor microenvironment plays in the pathogenesis of HIV-related malignancies. Understanding the functions of each component of the TME and determining how these cellular and noncellular components contribute to tumorigenesis will impact the advancement of interventions and treatment in clinical oncology among PWH.

Imaging and Radiologic-Pathologic Correlation in Granular Cell Astrocytomas: Report of 2 Cases

BACKGROUND

Granular cell astrocytoma is a rare and aggressive subtype of astrocytoma that is histopathologically well defined in the literature. It is formed by polygonal cells with granular cytoplasm mixed with neoplastic astrocytes and usually a perivascular infiltrate of lymphocytes. Despite its unusual histologic appearance, relevant radiologic features have not yet been described.

CASE DESCRIPTION

We report 2 middle-aged patients with neurologic symptoms secondary to a newly diagnosed brain tumor. The absence of central tumor necrosis as well as the presence of an atypical pattern of enhancement and areas of intense diffusion restriction on magnetic resonance imaging in both cases led to the diagnosis of primary central nervous system lymphoma. Histopathologic findings in both tumors showed an aggressive astrocytoma with a prominent granular cell population and perivascular lymphocytic cuffing in tissue, corresponding to a granular cell astrocytoma. Despite the favorable prognostic factors, including World Health Organization grades II and III astrocytomas and IDH mutations, the outcome was poor.

CONCLUSIONS

Granular cell astrocytomas can show unusual aggressive radiologic features that do not correspond to their histopathologic grade of malignancy. The presence of perivascular lymphocytic infiltrate may alter the typical radiologic appearance of common astrocytomas.

Whole Tumor Histogram Analysis Using DW MRI in Primary Central Nervous System Lymphoma Correlates with Tumor Biomarkers and Outcome

The ability to non-invasively predict outcomes and monitor treatment response in primary central nervous system lymphoma (PCNSL) is important as treatment regimens are constantly being trialed. The aim of this study was to assess the validity of using apparent diffusion coefficient (ADC) histogram values to predict Ki-67 expression, a tumor proliferation marker, and patient outcomes in PCNSL in both immunocompetent patients and patients living with HIV (PLWH). Qualitative PCNSL magnetic resonance imaging (MRI) characteristics from 93 patients (23 PLWH and 70 immunocompetent) were analyzed, and whole tumor segmentation was performed on the ADC maps. Quantitative histogram analyses of the segmentations were calculated. These measures were compared to PCNSL Ki-67 expression. Progression-free survival (PFS) and overall survival (OS) were analyzed via comparison to the International Primary Central Nervous System Lymphoma Collaboration Group Response Criteria. Associations between ADC measures and clinical outcomes were assessed using univariate and multivariate Cox proportional hazards models. Normalized ADC (nADC)_Min, nADC_Mean, nADC₁, nADC₅, and nADC₁₅ values were significantly associated with a poorer OS. nADC_Max, nADC_Mean, nADC₅, nADC₁₅, nADC₇₅, nADC₉₅, nADC₉₉ inversely correlated with Ki-67 expression. OS was also significantly associated with lesion hemorrhage. PFS was not significantly associated with ADC values but with lesion hemorrhage. ADC histogram values and related parameters can predict the degree of tumor proliferation and patient outcomes for primary central nervous system lymphoma patients and in both immunocompetent patients and patients living with HIV.

Multiple Brain Biopsies for Epstein-Barr Virus-Positive Diffuse Large B-Cell Lymphoma with Extensive Necrosis in a Posttransplant Patient

BACKGROUND

Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphoma (DLBCL) in an immunocompromised patient with organ transplantation demonstrated unusual brain magnetic resonance imaging (MRI) findings. Recognition of EBV-positive DLBCL by radiologists on MRI may prevent unnecessary neurosurgical resection, and it could be important to obtain viable cells for accurate diagnosis on stereotactic biopsy because of extensive necrosis.

CASE DESCRIPTION

A 62-year-old woman presented to the emergency department with left hemiparesis grade III and dysarthria lasting for 3 weeks. She underwent kidney transplantation in 2007 and was taking immunosuppressants and had hypothyroidism. Brain MRI showed a 3.8-cm peripheral enhancing lesion with extensive central necrosis in association with marked perilesional edema. The irregular ringlike enhancing lesion showed diffusion restriction and mildly increased regional cerebral blood volume in the rim portion of the mass. 11C-Methionine positron emission tomography revealed slightly increased uptake in the peripheral lesion. The provisional diagnosis was a high-grade glioma. Stereotactic multiple biopsies were performed for the central necrotic area and peripheral enhancing lesion. The nonenhancing areas showed only necrotic material, without viable cells, and the enhancing portion showed viable cells for an accurate diagnosis in a frozen biopsy specimen. The pathologic diagnosis was EBV-positive DLBCL with extensive necrosis. Positron emission tomography of the chest, abdomen, pelvis, and neck soft tissues ruled out systemic diseases. She underwent whole-brain radiotherapy at a dose of 30.6 Gy. Eight months later, her neurologic symptoms had improved, with a stable brain lesion and improved perilesional edema.

CONCLUSIONS

We report an immunocompromised patient with EBV-positive DLBCL, which showed atypical MRI findings, including extensive necrosis. Multiple biopsies were required for final diagnosis.

CNS Infections in Immunoincompetent Patients : Neuroradiological and Clinical Features

In patients with immunodeficiency the pathogen spectrum of central nervous system (CNS) infections is broader and different from that of immunocompetent patients. Numerous opportunistic infections are characterized by a high prevalence of viral, bacterial and parasitic pathogens, and depend on the type of impaired immune defense, for example impaired T‑cell or monocyte function, monoclonal antibody treatment, and impaired granulocyte function. Neuroradiological features as well as laboratory findings are often different and versatile in comparison to immunocompetent individuals and pathognomonic imaging findings do not exist; however, knowledge of possible pathways of pathogens in the CNS and preferred tissue affection may help in narrowing down differential diagnoses. Therefore, knowledge of the type of patient and the performed immunomodulatory therapy is essential for the neuroradiological assessment and the differential diagnostic considerations. Moreover, parenchymal reactions in the sense of an immune reconstitution inflammatory syndrome (IRIS) can occur when immunocompetence is restored. This review focus on the most common pathologies in immunocompromised patients, and an overview of imaging features but also of pathology and clinical aspects is given. The synopsis of anamnestic information, clinical findings and structured analysis of the lesion pattern, its spread and short-term follow-up may increase the correct diagnostic classification; however, the gold standard is still determination of the pathogen in the cerebrospinal fluid (CSF), blood cultures or biopsies.

Review of Radiologic Considerations in an Immunocompetent Patient With Primary Central Nervous System Lymphoma

Primary central nervous system lymphoma is increasingly seen in immunocompetent patients and should be considered in any patient with multiple nervous system lesions.

Clinical value of magnetic resonance imaging in identifying multiple cerebral gliomas from primary central nervous system lymphoma

Clinical value of magnetic resonance imaging (MRI) in identifying and diagnosing multiple cerebral glioma (MCG) from primary central nervous system lymphoma (PCNSL) was evaluated. A total of 21 patients with MCG diagnosed clinically and pathologically in Zhangzhou Municipal Hospital from March 2016 to April 2017 were selected as group A, and 30 patients with PCNSL diagnosed in Zhangzhou Affiliated Hospital of Fujian Medical University during the same period as group B. Plain MRI, enhanced MRI and diffusion weighted imaging (DWI) were performed in all patients, the apparent diffusion coefficient (ADC) value of lesions was measured, and the diagnostic efficacy of ADC for MCG and PCNSL was evaluated by receiver operating characteristic (ROC) curve. The incidence of hippocampus lesions, patchy and cystic lesions, and the heterogeneous signal of plain scan in group A was significantly higher than that in group B (P<0.05), and the incidence of basal ganglia lesions was significantly lower than that in group B (P<0.05). Mass lesions in group A were significantly less than those in group B (P<0.05). The ADC value of lesions in group A was significantly higher than that in contralateral normal white matter (P<0.05), the ADC value in group B was significantly lower than that in normal contralateral white matter (P<0.05), so the ADC value in group A was significantly higher than that in group B (P<0.05). The location, lesion shape and signal characteristic of MCG and PCNSL have their own specificity; there are significant differences in DWI signal and ADC color map signal intensity of the lesions; ADC has certain diagnostic value for MCG and PCNSL; the differential diagnosis of MCG from PCNSL by MRI is of great significance.

Necrotic Primary Central Nervous System Lymphoma in an Immunocompetent Patient: A Case Report and Literature Review

Primary lymphoma that arises de novo from the central nervous system (CNS) is most commonly a non-Hodgkin's B-cell lymphoma and by definition lacks the presence of disease outside the CNS. It demonstrates a characteristic imaging appearance on computed tomography (CT) and magnetic resonance imaging (MRI) exams related to its inherent hypercellularity. On CT, primary CNS lymphoma (PCNSL) demonstrates a hyperdense appearance; on MRI, it commonly demonstrates restricted water diffusion on diffusion-weighted sequences and homogeneous enhancement on post-contrast sequences. We present a case of primary CNS lymphoma in an immunocompetent patient with progressive necrosis and loss of restricted diffusion on diffusion-weighted imaging (DWI) with an atypical enhancement pattern. We further provide a review of the literature regarding the CT and MRI appearance of primary CNS lymphoma and discuss the role of immune status in determining the imaging characteristics of this disease process.

CT, conventional, and functional MRI features of skull lymphoma: a series of eight cases in a single institution

OBJECTIVE

With the hypothesis that the combination of CT, conventional, and functional MRI can indicate a possible diagnosis of skull lymphoma, this study aimed to systematically explore CT, conventional, and functional MRI features of this rare entity.

MATERIALS AND METHODS

This retrospective study included eight patients with pathologically confirmed skull lymphomas. CT and conventional MRI findings, including the location, size, attenuation/signal intensity, cystic/necrosis, hemorrhage, calcification, enhancement, skull change, brain parenchyma edema and adjacent structure invasion, were reviewed. We also reviewed multi-parametric functional MR imaging features obtained from diffusion-weighted imaging (DWI, n = 4), susceptibility-weighted imaging (SWI, n = 3) and dynamic susceptibility-weighted contrast-enhanced perfusion-weighted imaging (DSC-PWI, n = 1).

RESULTS

The eight patients in this series consisted of five males and three females, with a mean age of 51.1 years. All skull lymphomas showed the tumors extending to extra- and intra-cranial spaces with permeative destruction of the intervening skull. Intratumoral cystic/necrosis was seen in one case. Hemorrhage or calcification was absent. Dural mater infiltration was detected in all cases. Two clivus lymphomas encased internal carotid artery without narrowing the lumen. Three cases invaded brain parenchyma with moderate edema. The tumors demonstrated high signal on DWI with low ADC values comparing to muscles. SWI images showed little intratumoral hemorrhage and vessel. Low relative cerebral blood volume (rCBV) value was detected.

CONCLUSIONS

Skull lymphomas commonly presented as a homogenous solid tumor extending either intra- or extra-cranially with permeative bone destruction. Restricted diffusion, little intratumoral susceptibility signal, and lower perfusion may indicate a specific diagnosis. Multi-parametric functional MRI may be a promising tool for the diagnosis of skull lymphomas.

Subdural haematoma mimics

A subdural haematoma (SDH) is a frequently encountered pathology seen on an emergency room computed tomography (CT) head scan. An extra-axial crescentic density along the convexity of the brain or within the interhemispheric fissure is generally thought to represent a SDH; however, SDH mimics are known to occur in nature, and can be broadly classified under the subcategories of normal anatomy, artefacts, tumour, inflammation, infection, ischaemia, trauma, and iatrogenic. Understanding the typical characteristics of a SDH, knowledge of normal anatomy, close inspection of the morphology of the subdural process, changes to the adjacent structures, and rigorous attention to clinical details may reveal subtle clues that distinguish a true SDH from a mimic. This is crucial in appropriately directing clinical management. This review amalgamates most of the rare subdural processes that have been reported to mimic SDH, and discusses the imaging and clinical features that help to differentiate between them. This topic is highly valuable for radiology trainees, general radiologists, and emergency room physicians, and may serve as a refresher for the practising neuroradiologist.

Focal Intramedullary Spinal Cord Lesion in Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome: Toxoplasmosis Versus Lymphoma

BACKGROUND

Neurologic complications are common in patients with human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS). Although both the central nervous system (CNS) and the peripheral nervous system can be affected, 80% of patients with HIV/AIDS have CNS involvement during the course of their illness. The brain is the primary site of HIV/AIDS-associated CNS complications. Spinal cord involvement is rare, particularly focal intramedullary spinal cord lesions without any associated cerebral lesions. Among various opportunistic infections and malignancies, toxoplasmosis and CNS lymphoma are the most common causes of focal neurologic disease in patients with HIV/AIDS. Distinguishing between toxoplasmosis and CNS lymphoma is challenging, as the diseases have similar clinical presentations.

CASE DESCRIPTION

In a woman with newly diagnosed HIV infection, myelopathy manifested as an isolated, single intramedullary spinal cord lesion.

CONCLUSIONS

Common methods to distinguish the diagnoses of toxoplasmosis and CNS lymphoma are addressed. There should be a high index of suspicion for toxoplasmosis in patients with HIV/AIDS presenting with a focal intramedullary spinal cord lesion.

Radiomic features and multilayer perceptron network classifier: a robust MRI classification strategy for distinguishing glioblastoma from primary central nervous system lymphoma

We aimed to establish a high-performing and robust classification strategy, using magnetic resonance imaging (MRI), along with combinations of feature extraction and selection in human and machine learning using radiomics or deep features by employing a small dataset. Using diffusion and contrast-enhanced T1-weighted MR images obtained from patients with glioblastomas and primary central nervous system lymphomas, classification task was assigned to a combination of radiomic features and (1) supervised machine learning after feature selection or (2) multilayer perceptron (MLP) network; or MR image input without radiomic feature extraction to (3) two neuro-radiologists or (4) an end-to-end convolutional neural network (CNN). The results showed similar high performance in generalized linear model (GLM) classifier and MLP using radiomics features in the internal validation set, but MLP network remained robust in the external validation set obtained using different MRI protocols. CNN showed the lowest performance in both validation sets. Our results reveal that a combination of radiomic features and MLP network classifier serves a high-performing and generalizable model for classification task for a small dataset with heterogeneous MRI protocols.

A Case of Sarcoidosis-lymphoma Syndrome: Importance of Brain Biopsy

Sarcoidosis is occasionally associated with malignant lymphoma. Cases of sarcoidosis associated with malignant lymphoma are called sarcoidosis-lymphoma syndrome. We report a 63-year-old man with sarcoidosis associated with primary central nervous system lymphoma (PCNSL). Definitive diagnosis by clinical and radiological findings was difficult. Finally, brain biopsy could produce the correct diagnosis. We could provide appropriate treatment for PCNSL and the patient has survived over 2 years. Thus, it is very important to make an early definitive diagnosis by biopsy for intracranial lesion, because it can prolong survival in patients with sarcoidosis.

Primary central nervous system lymphoma in patients with and without HIV infection: a multicenter study and comparison with U.S national data

PURPOSE

Primary central nervous system lymphoma (PCNSL) in patients living with HIV (PLWH) is a distinct entity; however, the management is adopted from patients without HIV. The study aims to examine the differences in presentation, treatment, and outcomes of PCNSL patients with or without HIV.

METHODS

We retrospectively compared the characteristics of 144 patients with PCNSL with and without HIV, and analyzed factors associated with overall and progression-free survival. Results were compared to the Central Brain Tumor Registry of the United States (CBTRUS) and the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) system.

RESULTS

Among all patients with PCNSL, 19% had HIV. PLWH were younger (38 vs. 63 years; p < 0.01) and more likely to be African American (59% vs. 7%; p < 0.01) and male (74% vs. 49%; p = 0.02) than patients without HIV. PLWH were more likely to have multiple lesions (67% vs. 43%; p = 0.02), hemorrhage (59 vs. 37%; p = 0.03), and peripheral rim enhancement (57% vs. 7%; p < 0.01) on imaging; to receive palliative care (15% vs. 2%) or whole brain radiation (63% vs. 3%); and less likely to receive chemotherapy (22% vs. 95%) (p < 0.01). Twenty-four patients, none PLWH, underwent stem cell transplant. Not receiving transplant was an independent factor in mortality and disease progression. Our cohort of patients, compared to the national database, were younger (60 vs. 65 years), 58% were white vs. 75%, and had longer median overall survival 43 vs. 25 months.

CONCLUSION

Epidemiology, imaging, and treatment options for patients with PCNSL with and without HIV differ, but HIV was not an independent factor of mortality or disease progression. More efforts are needed to improve access to research and treatment options for PLWH with PCNSL.

Primary Central Nervous System Lymphoma: Molecular Pathogenesis and Advances in Treatment

Primary central nervous system lymphoma (PCNSL) is a group of extranodal non-Hodgkin lymphoma that exhibits specific biological characteristics and clinical behavior, with an aggressive disease course and unsatisfactory patient outcomes. It is of great importance to identify aberrant genetic loci and important molecular pathways that might suggest potential targets for new therapeutics and provide prognostic information. In this review, we listed various genetic and epigenetic alterations that are involved in PCNSL pathogenesis. In the aspect of treatment, we summarized the related literatures and evaluated the efficacy of surgery, induction chemotherapy, radiotherapy, intrathecal chemotherapy, and autologous stem cell transplantation in PCNSL. We also proposed the possible new agents for recurrent and relapse PCNSL based on the result of recent clinical researches.

Dural masses: meningiomas and their mimics

Meningiomas are the most common dural tumour. They are regularly being seen as an incidental finding on brain imaging and treated conservatively. However, there are many other dural masses which mimic their appearances, including primary neoplastic processes, metastases, granulomatous diseases and infection. While some of these are rare, others such as metastases and tuberculosis arise relatively frequently in practice. Although not pathognomonic, key features which increase the probability of a lesion being a meningioma include intralesional calcifications, skull hyperostosis, local dural enhancement and increased perfusion. It is important to have an awareness of these entities as well as their main imaging findings, as they have a wide range of prognoses and differing management strategies. This review outlines several of the most important mimics along with their imaging findings on both standard and advanced techniques with key features which may be used to help differentiate them from meningiomas.

Histogram Analysis of T1-Weighted, T2-Weighted, and Postcontrast T1-Weighted Images in Primary CNS Lymphoma: Correlations with Histopathological Findings-a Preliminary Study

PURPOSE

Previously, some reports mentioned that magnetic resonance imaging (MRI) can predict histopathological features in primary CNS lymphoma (PCNSL). The reported data analyzed diffusion-weighted imaging findings. The aim of this study was to investigate possible associations between histopathological findings, such as tumor cellularity, nucleic areas and proliferation index Ki-67, and signal intensity on T1-weighted and T2-weighted images in PCNSL.

PROCEDURES

For this study, 18 patients with PCNSL were retrospectively investigated by histogram analysis on precontrast and postcontrast T1-weighted and fluid-attenuated inversion recovery (FLAIR) images. For every patient, histopathology parameters, nucleic count, total nucleic area, and average nucleic area, as well as Ki-67 index, were estimated.

RESULTS

Correlation analysis identified several statistically significant associations. Skewness derived from precontrast T1-weighted images correlated with Ki-67 index (p = - 0.55, P = 0.028). Furthermore, entropy derived from precontrast T1-weighted images correlated with average nucleic area (p = 0.53, P = 0.04). Several parameters from postcontrast T1-weighted images correlated with nucleic count: maximum signal intensity (p = 0.59, P = 0.017), P75 (p = 0.56, P = 0.02), and P90 (p = 0.52, P = 0.04) as well as SD (p = 0.58, P = 0.02). Maximum signal intensity derived from FLAIR sequence correlated with nucleic count (p = 0.50, P = 0.03).

CONCLUSION

Histogram-derived parameters of conventional MRI sequences can reflect different histopathological features in PSNCL.

Imaging features (CT, MRI, MRS, and PET/CT) of primary central nervous system lymphoma in immunocompetent patients

Background

Because of the low incidence of primary central nervous system lymphoma (PCNSL) in non-HIV individuals and because of the lack of specific clinical manifestations and auxiliary examinations, the disease is easily missed or misdiagnosed.

Objective

To analyze the imaging features of PCNSL in non-HIV patients.

Methods

This was a retrospective study of patients with PCNSL treated between January 2001 and December 2011 at the Naval General Hospital (Beijing, China). All included patients were pathologically diagnosed with PCNSL. Specimens were obtained by stereotactic biopsy and diagnosed by pathological examination. Serological panel had to be negative for HIV.

Results

Out of the 118 patients, 73 (61.9%) were male and 45 (38.1%) were female. Median age was 54 (range 11–83) years. All patients had B cell lymphoma. The lesions showed slightly hyperintense shadows on computed tomography (CT) images, and mostly hyperintense T1 and iso- or hyperintense T2 signals on magnetic resonance imaging (MRI). Most lesions showed patchy enhancement after enhanced scanning, and some had the characteristic “butterfly sign” on enhanced MRI. The magnetic resonance spectroscopy of PCNSL manifested as increased Cho peak, moderately decreased NAA peak, and slightly decreased Cr peak. Positron emission computed tomography indicated high metabolism of ¹⁸F-FDG in PCNSL lesions.

Conclusion

MRI is important in the diagnosis of PCNSL. Understanding the imaging features of PCNSL will help improve its diagnosis in clinics.

MRI findings, including diffusion-weighted imaging and apparent diffusion coefficient value, in two cats with nasopharyngeal polyps and one cat with lymphoma

Objectives

Most nasopharyngeal masses in cats are lymphomas or polyps. To our knowledge, there is no report of MRI findings, including diffusion-weighted imaging (DWI) or apparent diffusion coefficient (ADC) values, of nasopharyngeal lymphomas and nasopharyngeal polyps in cats. This study aimed to evaluate the MRI findings of nasopharyngeal lymphomas and nasopharyngeal polyps, including DWI and ADC values.

Methods

MRI examination was performed on two cats with a histologically confirmed nasopharyngeal polyp and one cat with lymphoma. The magnetic resonance scanning protocol included T2-weighted imaging (T2WI), T1-weighted imaging (T1WI) and DWI. An ADC map was created based on DWI. ADC values were then calculated.

Results

MRI of the nasopharyngeal polyps revealed well-defined masses with strong rim enhancement, mass-associated stalk-like structures and asymmetric tympanic bulla lesions. The polyps appeared hyperintense on T2WI, hypo- to isointense on T1WI, and of mixed intensity or hypointense on DWI. On the ADC map, the masses appeared hyperintense. The ADC values of the polyps were 2.07 × 10^-3 mm²/s and 2.28 × 10^-3 mm²/s. MRI examination of the nasopharyngeal lymphoma revealed a strongly enhancing heterogeneous lesion. The mass appeared mildly hyperintense on T2WI, isointense on T1WI and hyperintense on DWI. On the ADC map, the mass appeared hypointense. The ADC value of the mass was 0.46 ×10^-3 mm²/s. The ADC values of the nasopharyngeal polyps were higher than the ADC value of the nasopharyngeal lymphoma.

Conclusions and relevance

Measurement of ADC values may be useful for differentiating between nasopharyngeal polyps and nasopharyngeal lymphomas.

Comparative study on different therapies on patients with primary central nervous system lymphoma

Objective

To compare and analyze three therapies on patients with primary central nervous system lymphoma (PCNSL), aiming to provide evidences for future treatment and prognosis.

Methods

Clinical data of 26 cases of PCNSL with normal immune system confirmed by postoperative pathology were retrospectively analyzed. Among them there were six cases with operation only, nine cases with operation and radiotherapy, and 11 cases with operation, radiotherapy and chemotherapy, and their survival rate was compared as well.

Results

The survival time of patients with operation only, operation combined with radiotherapy and operation combined with radiotherapy and chemotherapy was 6–11 months, 15–24 months and 24–51 months, respectively. And their median survival time was only nine months, 21 months and 38 months, respectively.

Conclusions

Operation combined with radiotherapy and chemotherapy can dramatically extend PCNSL patients’ survival time, therefore, it can be regarded as the first-line therapy.

Primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) is a rare and aggressive extranodal non-Hodgkin lymphoma (NHL), confined to the brain, eyes, spinal cord or leptomeninges without systemic involvement. Overall prognosis, diagnosis and management of PCNSL differ from other types of NHL. Prompt diagnosis and initiation of treatment are vital to improving clinical outcomes. PCNSL is responsive to radiation therapy, however whole-brain radiotherapy (WBRT) inadequately controls the disease when used alone and its delayed neurotoxicity causes neurocognitive impairment, especially in elderly patients. High-dose methotrexate (HD-MTX)-based induction chemotherapy with or without autologous stem cell transplantation (ASCT) or reduced-dose WBRT leads to durable disease control and less neurotoxicity. The optimal treatment has yet to be defined, however HD-MTX-based induction chemotherapy is considered standard for newly diagnosed PCNSL. Ongoing randomized trials address the role of rituximab, and of consolidative treatment using ASCT or reduced-dose WBRT. Despite high tumor response rates to initial treatment, many patients have relapsing disease with very poor prognosis. The optimal treatment for refractory or relapsed PCNSL is poorly defined. The choice of salvage treatment depends on age, previous treatment and response, performance status and comorbidities at the time of relapse. Novel therapeutics targeting underlying tumor biology include small molecule inhibitors of B-cell receptor, cereblon, and mammalian target of rapamycin signaling, and immunotherapy programmed cell death 1 receptor inhibitors and chimeric antigen receptor T cells.

Contrast-enhanced computed tomography may be helpful for characterizing and staging canine gastric tumors

In humans, computed tomography (CT) is a widely performed technique for the diagnosis and staging of gastric tumors. The purpose of this retrospective case series study was to describe CT findings in a group of dogs with confirmed gastric tumors. For each included dog, the following CT parameters were recorded: gastric tumor location, tumor shape, gastric involvement pattern, tumor enhancement pattern in early and late phases, presence and location of lymphadenopathy, gastric tumor attenuation values, attenuation values of enlarged lymph nodes, maximum short-axis diameter (mm) of enlarged lymph node, maximum long-axis diameter (mm) of enlarged lymph node, and short-axis diameter to long-axis diameter ratio (short axis/long axis). A total of 16 dogs met inclusion criteria and had the following final diagnoses: five lymphoma, six adenocarcinoma, three inflammatory polyps, and two leiomyoma. In the early- and delayed-phase postcontrast images, the mean CT attenuation value for lymphoma was lower than that of other gastric tumors. Lymphadenopathy was widespread in lymphomas and regional in adenocarcinomas. Lymphadenopathy was not detected in leiomyomas. Lymph node measurements in lymphoma were larger than lymph node measurements in adenocarcinoma. Although there were overlapping findings for the different types of gastric tumors, contrast-enhanced CT provided helpful information for characterizing gastric tumors based on the following criteria: early and late enhancement patterns, the site of origin of the mass lesion, and extent of local invasion and distant metastases. Lymphoma should be considered for canine gastric tumors with low mean attenuation values during early- and delayed-phase postcontrast images, and widespread, bulky, and rounded lymphadenopathy.

[18F]Fludarabine-PET as a promising tool for differentiating CNS lymphoma and glioblastoma: Comparative analysis with [18F]FDG in human xenograft models

This paper investigated whether positron emission tomography (PET) imaging with [¹⁸F]fludarabine ([¹⁸F]FDB) can help to differentiate central nervous system lymphoma (CNSL) from glioblastoma (GBM), which is a crucial issue in the diagnosis and management of patients with these aggressive brain tumors. Multimodal analyses with [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG), magnetic resonance imaging (MRI) and histology have also been considered to address the specificity of [¹⁸F]FDB for CNSL. Methods: Nude rats were implanted with human MC116 lymphoma-cells (n = 9) or U87 glioma-cells (n = 4). Tumor growth was monitored by MRI, with T2-weighted sequence for anatomical features and T1-weighted with gadolinium (Gd) enhancement for blood brain barrier (BBB) permeability assessment. For PET investigation, [¹⁸F]FDB or [¹⁸F]FDG (~11 MBq) were injected via tail vein and dynamic PET images were acquired up to 90 min after radiotracer injection. Paired scans of the same rat with the two [¹⁸F]-labelled radiotracers were investigated. Initial volumes of interest were manually delineated on T2w images and set on co-registered PET images and tumor-to-background ratio (TBR) was calculated to semi-quantitatively assess the tracer accumulation in the tumor. A tile-based method for image analysis was developed in order to make comparative analysis between radiotracer uptake and values extracted from immunohistochemistry staining. Results: In the lymphoma model, PET time-activity curves (TACs) revealed a differential response of [¹⁸F]FDB between tumoral and healthy tissues with average TBR varying from 2.45 to 3.16 between 5 to 90 min post-injection. In contrast, [¹⁸F]FDG demonstrated similar uptake profiles for tumoral and normal regions with TBR varying from 0.84 to 1.06 between these two time points. In the glioblastoma (GBM) model, the average TBRs were from 2.14 to 1.01 for [¹⁸F]FDB and from 0.95 to 1.65 for [¹⁸F]FDG. Therefore, inter-model comparisons showed significantly divergent responses (p < 0.01) of [¹⁸F]FDB between lymphoma and GBM, while [¹⁸F]FDG demonstrated overlap (p = 0.04) between the groups. Tumor characterization with histology (based mainly on Hoechst and CD79), as well as with MRI was overall in better agreement with [¹⁸F]FDB-PET than [¹⁸F]FDG with regard to tumor selectivity. Conclusions: [¹⁸F]FDB-PET demonstrated considerably greater specificity for CNSL when compared to [¹⁸F]FDG. It also permitted a more precise definition of target volume compared to contrast-enhanced MRI. Therefore, the potential of [¹⁸F]FDB-PET to distinguish CNSL from GBM is quite evident and will be further investigated in humans.

Diffusion radiomics as a diagnostic model for atypical manifestation of primary central nervous system lymphoma: development and multicenter external validation

Background

Radiomics is a rapidly growing field in neuro-oncology, but studies have been limited to conventional MRI, and external validation is critically lacking. We evaluated technical feasibility, diagnostic performance, and generalizability of a diffusion radiomics model for identifying atypical primary central nervous system lymphoma (PCNSL) mimicking glioblastoma.

Methods

A total of 1618 radiomics features were extracted from diffusion and conventional MRI from 112 patients (training set, 70 glioblastomas and 42 PCNSLs). Feature selection and classification were optimized using a machine-learning algorithm. The diagnostic performance was tested in 42 patients of internal and external validation sets. The performance was compared with that of human readers (2 neuroimaging experts), cerebral blood volume (90% histogram cutoff, CBV90), and apparent diffusion coefficient (10% histogram, ADC10) using the area under the receiver operating characteristic curve (AUC).

Results

The diffusion radiomics was optimized with the combination of recursive feature elimination and a random forest classifier (AUC 0.983, stability 2.52%). In internal validation, the diffusion model (AUC 0.984) showed similar performance with conventional (AUC 0.968) or combined diffusion and conventional radiomics (AUC 0.984) and better than human readers (AUC 0.825-0.908), CBV90 (AUC 0.905), or ADC10 (AUC 0.787) in atypical PCNSL diagnosis. In external validation, the diffusion radiomics showed robustness (AUC 0.944) and performed better than conventional radiomics (AUC 0.819) and similar to combined radiomics (AUC 0.946) or human readers (AUC 0.896-0.930).

Conclusion

The diffusion radiomics model had good generalizability and yielded a better diagnostic performance than conventional radiomics or single advanced MRI in identifying atypical PCNSL mimicking glioblastoma.

Primary CNS Lymphomas: Challenges in Diagnosis and Monitoring

Primary Central Nervous System Lymphoma (PCNSL) is a rare neoplasm that can involve brain, eye, leptomeninges, and rarely spinal cord. PCNSL lesions most typically enhance homogeneously on T1-weighted magnetic resonance imaging (MRI) and appear T2-hypointense, but high variability in MRI features is commonly encountered. Neurological symptoms and MRI findings may mimic high grade gliomas (HGGs), tumefactive demyelinating lesions (TDLs), or infectious and granulomatous diseases. Advanced MRI techniques (MR diffusion, spectroscopy, and perfusion) and metabolic imaging, such as Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) or amino acid PET (usually employing methionine), may be useful in distinguishing these different entities and monitoring the disease course. Moreover, emerging data suggest a role for cerebrospinal fluid (CSF) markers in predicting prognosis and response to treatments. In this review, we will address the challenges in PCNSL diagnosis, assessment of response to treatments, and evaluation of potential neurotoxicity related to chemotherapy and radiotherapy.

Prognostic Significance of Interim 11C-Methionine PET/CT in Primary Central Nervous System Lymphoma

PURPOSE

Primary central nervous system lymphoma (PCNSL) has a poor prognosis. There has been limited study evaluating the role of interim PET/CT in PCNSL. This prospective study investigated the interim response using sequential brain PET/CT with C-methionine (C-MET) to provide prognostic information during the treatment of PCNSL.

MATERIALS AND METHODS

A total of 26 immunocompetent patients recently diagnosed with PCNSL were evaluated. Brain MRI and C-MET PET/CT were performed at the time of diagnosis and after 4 cycles of high-dose methotrexate-based induction chemotherapy. Tumor-to-normal tissue (T/N) ratio and MTV were used to assess the interim response.

RESULTS

All patients had diffuse large B-cell lymphoma. No differences were observed in initial tumor volume or quantitative uptake among the International Extranodal Lymphoma Study Group groups. Higher International Extranodal Lymphoma Study Group risk scores were associated with higher median values for interim MTV and T/N ratios, as well as poor outcomes. After a median follow-up of 21 months, interim C-MET PET/CT assessments based on the quantitative T/N ratio and MTV predicted progression-free survival and overall survival, respectively. A high interim T/N ratio was significantly associated with decreased progression-free survival (hazards ratio, 3.68; P = 0.044).

CONCLUSIONS

Response assessments based on interim C-MET PET/CT could predict the therapeutic outcome of PCNSL.

Diagnostic markers for CNS lymphoma in blood and cerebrospinal fluid: a systematic review

Diagnosing central nervous system (CNS) lymphoma remains a challenge. Most patients have to undergo brain biopsy to obtain tissue for diagnosis, with associated risks of serious complications. Diagnostic markers in blood or cerebrospinal fluid (CSF) could facilitate early diagnosis with low complication rates. We performed a systematic literature search for studies on markers in blood or cerebrospinal fluid for the diagnosis CNS lymphoma and assessed the methodological quality of studies with the Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS‐2). We evaluated diagnostic value of the markers at a given threshold, as well as differences between mean or median levels in patients versus control groups. Twenty‐five studies were included, reporting diagnostic value for 18 markers in CSF (microRNAs ‐21, ‐19b, and ‐92a, RNU2‐1f, CXCL13, interleukins ‐6, ‐8, and ‐10, soluble interleukin‐2‐receptor, soluble CD19, soluble CD27, tumour necrosis factor‐alfa, beta‐2‐microglobulin, antithrombin III, soluble transmembrane activator and calcium modulator and cyclophilin ligand interactor, soluble B cell maturation antigen, neopterin and osteopontin) and three markers in blood (microRNA‐21 soluble CD27, and beta‐2‐microglobulin). All studies were at considerable risk of bias and there were concerns regarding the applicability of 15 studies. CXCL‐13, beta‐2‐microglobulin and neopterin have the highest potential in diagnosing CNS lymphoma, but further study is still needed before they can be used in clinical practice.

Intracranial Infectious and Inflammatory Diseases Presenting as Neurosurgical Pathologies

There are many infectious and inflammatory processes affecting the central nervous system that can simulate other neurosurgical pathologies (e.g. tumor) and may precipitate a brain biopsy for definitive diagnosis if not suspected a priori. The challenge for the healthcare team is to recognize imaging features that support a nonsurgical pathology to avoid unnecessary interventions. This review aims to give a general overview of some common inflammatory and infectious entities that affect the central nervous system, with illustrative examples and highlighting important pearls and pitfalls.

Primary central nervous system lymphoma and atypical glioblastoma: Differentiation using radiomics approach

OBJECTIVES

To evaluate the diagnostic performance of magnetic resonance (MR) radiomics-based machine-learning algorithms in differentiating primary central nervous system lymphoma (PCNSL) from non-necrotic atypical glioblastoma (GBM).

METHODS

Seventy-seven patients (54 individuals with PCNSL and 23 with non-necrotic atypical GBM), diagnosed from January 2009 to April 2017, were enrolled in this retrospective study. A total of 6,366 radiomics features, including shape, volume, first-order, texture, and wavelet-transformed features, were extracted from multi-parametric (post-contrast T1- and T2-weighted, and fluid attenuation inversion recovery images) and multiregional (enhanced and non-enhanced) tumour volumes. These features were subjected to recursive feature elimination and random forest (RF) analysis with nested cross-validation. The diagnostic abilities of a radiomics machine-learning classifier, apparent diffusion coefficient (ADC), and three readers, who independently classified the tumours based on conventional MR sequences, were evaluated using receiver operating characteristic (ROC) analysis. Areas under the ROC curves (AUC) of the radiomics classifier, ADC value, and the radiologists were compared.

RESULTS

The mean AUC of the radiomics classifier was 0.921 (95 % CI 0.825-0.990). The AUCs of the three readers and ADC were 0.707 (95 % CI 0.622-0.793), 0.759 (95 %CI 0.656-0.861), 0.695 (95 % CI 0.590-0.800) and 0.684 (95 % CI0.560-0.809), respectively. The AUC of the radiomics-based classifier was significantly higher than those of the three readers and ADC (p< 0.001 for all).

CONCLUSIONS

Large-scale radiomics with a machine-learning algorithm can be useful for differentiating PCNSL from atypical GBM, and yields a better diagnostic performance than human radiologists and ADC values.

KEY POINTS

• Machine-learning algorithm radiomics can help to differentiate primary central PCNSL from GBM. • This approach yields a higher diagnostic accuracy than visual analysis by radiologists. • Radiomics can strengthen radiologists' diagnostic decisions whenever conventional MRI sequences are available.

Sparse Representation-Based Radiomics for the Diagnosis of Brain Tumors

Brain tumors are the most common malignant neurologic tumors with the highest mortality and disability rate. Because of the delicate structure of the brain, the clinical use of several commonly used biopsy diagnosis is limited for brain tumors. Radiomics is an emerging technique for noninvasive diagnosis based on quantitative medical image analyses. However, current radiomics techniques are not standardized regarding feature extraction, feature selection, and decision making. In this paper, we propose a sparse representation-based radiomics (SRR) system for the diagnosis of brain tumors. First, we developed a dictionary learning- and sparse representation-based feature extraction method that exploits the statistical characteristics of the lesion area, leading to fine and more effective feature extraction compared with the traditional explicitly calculation-based methods. Then, we set up an iterative sparse representation method to solve the redundancy problem of the extracted features. Finally, we proposed a novel multi-feature collaborative sparse representation classification framework that introduces a new coefficient of regularization term to combine features from multi-modal images at the sparse representation coefficient level. Two clinical problems were used to validate the performance and usefulness of the proposed SRR system. One was the differential diagnosis between primary central nervous system lymphoma (PCNSL) and glioblastoma (GBM), and the other was isocitrate dehydrogenase 1 estimation for gliomas. The SRR system had superior PCNSL and GBM differentiation performance compared with some advanced imaging techniques and yielded 11% better performance for estimating IDH1 compared with the traditional radiomics methods.

Diagnostic Accuracy of Unenhanced CT Analysis to Differentiate Low-Grade From High-Grade Chromophobe Renal Cell Carcinoma

OBJECTIVE

The objective of our study was to evaluate tumor attenuation and texture on unenhanced CT for potential differentiation of low-grade from high-grade chromophobe renal cell carcinoma (RCC).

MATERIALS AND METHODS

A retrospective study of 37 consecutive patients with chromophobe RCC (high-grade, n = 13; low-grade, n = 24) who underwent preoperative unenhanced CT between 2011 and 2016 was performed. Two radiologists (readers 1 and 2) blinded to the histologic grade of the tumor and outcome of the patients subjectively evaluated tumor homogeneity (3-point scale: completely homogeneous, mildly heterogeneous, or mostly heterogeneous). A third radiologist, also blinded to tumor grade and patient outcome, measured attenuation and contoured tumors for quantitative texture analysis. Comparisons were performed between high-grade and low-grade tumors using the chi-square test for subjective variables and sex, independent t tests for patient age and tumor attenuation, and Mann-Whitney U tests for texture analysis. Logistic regression models and ROC curves were computed.

RESULTS

There were no differences in age or sex between the groups (p = 0.652 and 0.076). High-grade tumors were larger (mean ± SD, 62.6 ± 34.9 mm [range, 17.0-141.0 mm] vs 39.0 ± 17.9 mm [16.0-72.3 mm]; p = 0.009) and had higher attenuation (mean ± SD, 45.5 ± 8.2 HU [range, 29.0-55.0 HU] vs 35.3 ± 8.5 HU [14.0-51.0 HU]; p = 0.001) than low-grade tumors. CT size and attenuation achieved good accuracy to diagnose high-grade chromophobe RCC: The AUC ± standard error was 0.85 ± 0.08 (p < 0.0001) with a sensitivity of 69.0% and a specificity of 100%. Subjectively, high-grade tumors were more heterogeneous (mildly or markedly heterogeneous: 69.2% [9/13] for reader 1 and 76.9% [10/13] for reader 2; reader 1, p = 0.024; reader 2, p = 0.001) with moderate agreement (κ = 0.57). Combined texture features diagnosed high-grade tumors with a maximal AUC of 0.84 ± 0.06 (p < 0.0001).

CONCLUSION

Tumor attenuation and heterogeneity assessed on unenhanced CT are associated with high-grade chromophobe RCC and correlate well with the histopathologic chromophobe tumor grading system.

Whole Tumor Histogram-profiling of Diffusion-Weighted Magnetic Resonance Images Reflects Tumorbiological Features of Primary Central Nervous System Lymphoma

PURPOSE: Diffusion weighted imaging (DWI) quantifies motion of hydrogen nuclei in biological tissues and hereby has been used to assess the underlying tissue microarchitecture. Histogram-profiling of DWI provides more detailed information on diffusion characteristics of a lesion than the standardly calculated values of the apparent diffusion coefficient (ADC)—minimum, mean and maximum. Hence, the aim of our study was to investigate, which parameters of histogram-profiling of DWI in primary central nervous system lymphoma can be used to specifically predict features like cellular density, chromatin content and proliferative activity. PROCEDURES: Pre-treatment ADC maps of 21 PCNSL patients (8 female, 13 male, 28–89 years) from a 1.5T system were used for Matlab-based histogram profiling. Results of histopathology (H&E staining) and immunohistochemistry (Ki-67 expression) were quantified. Correlations between histogram-profiling parameters and neuropathologic examination were calculated using SPSS 23.0. RESULTS: The lower percentiles (p10 and p25) showed significant correlations with structural parameters of the neuropathologic examination (cellular density, chromatin content). The highest percentile, p90, correlated significantly with Ki-67 expression, resembling proliferative activity. Kurtosis of the ADC histogram correlated significantly with cellular density. CONCLUSIONS: Histogram-profiling of DWI in PCNSL provides a comprehensible set of parameters, which reflect distinct tumor-architectural and tumor-biological features, and hence, are promising biomarkers for treatment response and prognosis.

Primary central nervous system lymphoma in immunocompetent patients: spectrum of findings and differential characteristics

Primary central nervous system (CNS) lymphomas are uncommon and their management differs significantly from that of other malignant tumors involving the CNS. This article explains how the imaging findings often suggest the diagnosis early. The typical findings in immunocompetent patients consist of a supratentorial intraaxial mass that enhances homogeneously. Other findings to evaluate include multifocality and incomplete ring enhancement. The differential diagnosis of primary CNS lymphomas should consider mainly other malignant tumors of the CNS such as glioblastomas or metastases. Primary CNS lymphomas tend to have less edema and less mass effect; they also tend to spare the adjacent cortex. Necrosis, hemorrhage, and calcification are uncommon in primary CNS lymphomas. Although the findings in morphologic sequences are characteristic, they are not completely specific and atypical types are sometimes encountered. Advanced imaging techniques such as diffusion or especially perfusion provide qualitative and quantitative data that play an important role in differentiating primary CNS lymphomas from other brain tumors.