MR imaging of hemorrhagic intracranial neoplasms

Sample strategies for the assessment of the apparent diffusion coefficient in single large intracranial space-occupying lesions of dogs and cats

Diffusion-weighted imaging is increasingly available for brain investigation. Image interpretation of intracranial space-occupying lesions often includes the derived apparent diffusion coefficient (ADC) analysis. In human medicine, ADC can help discriminate between benign and malignant lesions in intracranial tumors. This study investigates the difference in ADC values depending on the sample strategies of image analysis. MRI examination, including diffusion-weighted images of canine and feline patients presented between 2015 and 2020, were reviewed retrospectively. Patients with single, large intracranial space-occupying lesions were included. Lesions homogeneity was subjectively scored. ADC values were calculated using six different methods of sampling (M1-M6) on the ADC map. M1 included as much as possible of the lesion on a maximum of five consecutive slices; M2 included five central and five peripheral ROIs; M3 included a single ROI on the solid part of the lesion; M4 included three central ROIs on one slice; M5 included three central ROIs on different slices; and M6 included one large ROI on the entire lesion. A total of 201 animals of various breeds, genders, and ages were analyzed. ADC values differed significantly between M5 against M2 (peripheral) (p < 0.001), M5 against M6 (p = 0.009), and M4 against M2 (peripheral) (p = 0.005). When lesions scored as homogeneous in all sequences were excluded, an additional significant difference in three further sampling methods was present (p < 0.005). ADC of single, large, intracranial space-occupying lesions differed significantly in half of the tested methods of sampling. Excluding homogeneous lesions, additional significant differences among the sampling methods were present. The obtained results should increase awareness of the variability of the ADC, depending on the sample strategies used.

Clinicopathological features, current status, and progress of primary central nervous system melanoma diagnosis and treatment

Primary central nervous system (CNS) melanoma is an extremely rare condition, with an incidence rate of 0.01 per 100,000 individuals per year. Despite its rarity, the etiology and pathogenesis of this disease are not yet fully understood. Primary CNS melanoma exhibits highly aggressive biological behavior and presents clinically in a distinct manner from other types of melanomas. It can develop at any age, predominantly affecting the meninges as the primary site, with clinical symptoms varying depending on the neoplasm's location. Due to the lack of specificity in its presentation and the challenging nature of imaging diagnosis, distinguishing primary CNS melanoma from other CNS diseases. The combination of challenges in early detection, heightened tumor aggressiveness, and the obscured location of its origin contribute to an unfavorable prognostic outcome. Furthermore, there has been currently no consensus on a standardized treatment approach for primary CNS melanoma. Despite recent advancements in targeted therapy and immunotherapy for CNS melanoma, patients with primary CNS melanoma have limited treatment options due to their inadequate response to these therapies. Here, we provided a comprehensive summary of the epidemiology, clinical features, molecular pathological manifestations, and available diagnostic and therapeutic approaches of primary CNS melanoma. Additionally, we proposed potential therapeutic strategies for it.

Primary and secondary non-traumatic intra-cerebral haemorrhage: MRI findings

Intracranial haemorrhage (ICH) accounts for 10-30% of strokes, being the form with the worst prognosis. The causes of cerebral haemorrhage can be both primary, mainly hypertensive and amyloid angiopathy, and secondary, such as tumours or vascular lesions. Identifying the aetiology of bleeding is essential since it determines the treatment to be performed and the patient's prognosis. The main objective of this review is to review the main magnetic resonance imaging (MRI) findings of the primary and secondary causes of ICH, focusing on those radiological signs that help guide bleeding due to primary angiopathy or secondary to an underlying lesion. The indications for MRI in the event of non-traumatic intracranial haemorrhage will also be reviewed.

A Case of Haemorrhagic-Onset Glioblastoma With Delayed Diagnosis

Glioblastoma sometimes develops with acute onset due to intracerebral hemorrhage. Although it is sometimes difficult to diagnose patients with hemorrhagic-onset glioblastoma at the acute phase of intracerebral hemorrhage (ICH), the progressive enlargement of perifocal edema or the development of contrast-enhanced lesion triggers the diagnosis of glioblastoma within six months. Herein, we present a rare case of glioblastoma in which the diagnosis was delayed as long as 17 months after ICH. A 62-year-old man presented with a headache and aphasia. Computed tomography revealed ICH in the left temporal lobe. Magnetic resonance (MR) images revealed that the hematoma had a mix of isointense and surrounding hypointense lesions on T1-weighted MR images and gadolinium-enhanced lesions at the wall and the septum of the hematoma. An endoscopic evacuation of the hematoma was performed. No causative lesions were found during intraoperative and histological examinations. After seven months, abnormal signals were completely resolved on MR images, except for the small and stable enhanced lesion on three-dimensional gadolinium-enhanced T1-weighted MR imaging (3D Gd-T1WI) at the base of the hematoma, which did not change in size for seven months. However, a large gadolinium-enhanced lesion at the left temporal lobe developed 17 months after ICH. He underwent total resection of the lesion and was diagnosed with glioblastoma. He received radiation therapy and temozolomide but died of disseminated recurrence 31 months after ICH. In conclusion, this report presents a didactic case of glioblastoma in which the diagnosis of glioblastoma was delayed 17 months after ICH whereas hemorrhagic-onset glioblastoma was previously considered ruled out in cases in which six months or more have passed after ICH. In order not to overlook these cases, follow-up with 3D Gd-T1WI is essential in the case of suspected tumor-related ICH and close follow-up is recommended when the enhanced lesion does not resolve after a long period even if it does not grow.

ISRS Technical Guidelines for Stereotactic Radiosurgery: Treatment of Small Brain Metastases (≤1 cm in Diameter)

PURPOSE

The objective of this literature review was to develop International Stereotactic Radiosurgery Society (ISRS) consensus technical guidelines for the treatment of small, ≤1 cm in maximal diameter, intracranial metastases with stereotactic radiosurgery. Although different stereotactic radiosurgery technologies are available, most of them have similar treatment workflows and common technical challenges that are described.

METHODS AND MATERIALS

A systematic review of the literature published between 2009 and 2020 was performed in Pubmed using the Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA) methodology. The search terms were limited to those related to radiosurgery of brain metastases and to publications in the English language.

RESULTS

From 484 collected abstract 37 articles were included into the detailed review and bibliographic analysis. An additional 44 papers were identified as relevant from a search of the references. The 81 papers, including additional 7 international guidelines, were deemed relevant to at least one of five areas that were considered paramount for this report. These areas of technical focus have been employed to structure these guidelines: imaging specifications, target volume delineation and localization practices, use of margins, treatment planning techniques, and patient positioning.

CONCLUSION

This systematic review has demonstrated that Stereotactic Radiosurgery (SRS) for small (1 cm) brain metastases can be safely performed on both Gamma Knife (GK) and CyberKnife (CK) as well as on modern LINACs, specifically tailored for radiosurgical procedures, However, considerable expertise and resources are required for a program based on the latest evidence for best practice.

1.5 Tesla Magnetic Resonance Imaging Features of Canine Intracranial Intra-axial Hematomas

The differentiation of solitary intra-axial hematomas from hemorrhagic neoplasms based on their magnetic resonance imaging (MRI) features is challenging. The treatment and prognosis for these two disease entities are vastly different and distinction between them is often based on MRI findings alone. The aim of this study was to describe the 1.5 tesla MRI features of canine intra-axial hematomas and correlate these findings with the evolution of hemorrhages described in human brains. Retrospective evaluation of patient details, clinical signs, and MRI findings of dogs with intra-axial hematomas that were histopathologically confirmed or determined via repeat MRI study and/or resolution of neurological signs. Ten dogs met the inclusion criteria. All 10 hematoma lesions were determined to be 2–7 days in age. On MRI, all 10 hemorrhagic lesions were comprised of two distinct regions; a relatively thin T1-weighted (T1W), T2-weighted (T2W) and gradient echo (GRE) hypointense (9/10) peripheral border region and a large central region that was heterogenous but predominantly T1W, T2W and GRE hyperintense (8/10). The peripheral border region was complete in its integrity in all 10 cases on T2W and GRE sequences. Contrast enhancement was present in (6/10) hematoma lesions and was always peripheral in nature with no evidence of central enhancement associated with any of the lesions. An intra-axial hematoma should be suspected in solitary hemorrhagic space occupying lesions that have a complete hypointense peripheral rim, elicit a peripheral contrast enhancement pattern, and display the expected temporal pattern of hematoma evolution.

Neoplastic and Non-Neoplastic Causes of Acute Intracerebral Hemorrhage on CT : The Diagnostic Value of Perihematomal Edema

OBJECTIVE

The aim of this study was to investigate the diagnostic value of perihematomal edema (PHE) volume in non-enhanced computed tomography (NECT) to discriminate neoplastic and non-neoplastic causes of acute intracerebral hemorrhage (ICH).

METHODS

In this retrospective study, from 560 patients with acute ICH 91 patients fulfilled the inclusion criteria and were classified into neoplastic and non-neoplastic ICH. For each patient, ICH and total hemorrhage volume (ICH + PHE) were segmented semiautomatically. The PHE volume and relative PHE were further calculated and all parameters were compared between the different groups. Additionally, hematoma density was measured and compared between the groups.

RESULTS

The PHE volume and relative PHE on NECT were significantly higher in neoplastic vs. the non-neoplastic ICH (p = 0.003 and p < 0.001, respectively). Absolute ICH volume, symptom time onset to CT and ICH localization showed no significant difference between the two groups (p > 0.1). Univariate receiver operating characteristics (ROC) analysis revealed a high diagnostic performance for relative PHE in the discrimination of neoplastic and non-neoplastic ICH with an optimal cut-off of 0.50 (area under the curve, AUC 0.81, 60.0% sensitivity, 91.8% specificity), followed by PHE (AUC 0.69) and hematoma density (AUC 0.68).

CONCLUSION

Relative PHE with a cut-off of >0.50 is a specific and simple indicator for neoplastic causes of acute ICH and a potential tool for clinical implementation. This observation needs to be validated in an independent patient cohort.

Glioblastoma multiforme subterfuge as acute cerebral hemorrhage: A case report and literature review

Hemorrhagic related Glioblastoma multiforme (GBM) are rare and characterizes with severe clinical scuffle. The etiology of this presentation although not well known is believed to be multifactorial. We present a case as well as review on the pathogenesis of evolution of the hematoma into ring enhancing features of GBM on imaging studies. We present a case of 28 years old man who suddenly went into coma for 9 hours preceded with seizures that latest for 10 minutes. He had no focal neurological signs. CT-Scans images indicated acute cerebral hemorrhage near the frontal horn of the left ventricle with brain edema about the hemorrhagic lesion and MRI done a week later revealed a cerebral ring enhancing lesion. The lesion was partially resected during surgery and immunohistochemical staining confirmed GBM (WHO, grade 4). The diagnosis of intratumoral hemorrhage in GBM was very challenging at the initial stages but with time the hematoma evolved into ring enhancing images typical of GBM. It's not every intracranial hematoma that is of pure vascular origin.

Diagnosing Neoplastic Hematoma: Role of MR Perfusion

BACKGROUND

The imaging appearance of neoplastic hematoma can be complicated by the presence of a large hematoma, even on magnetic resonance imaging (MRI). We describe the role of MR perfusion (MRP) in detecting neoplastic hematomas in patients with intraparenchymal hematoma (IPH).

MATERIAL AND METHODS

A retrospective review was performed for consecutive patients with IPH, where MRP was performed. Routine, post-gadolinium MRI and MRP were analyzed. All patients were either operated on for evacuation of IPH or followed up on imaging. The MRP parameters of cerebral blood volume (CBV) and cerebral blood flow (CBF) and pattern of enhancement (peripheral linear vs. nodular) were recorded. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated for these parameters for diagnosing neoplastic hematoma.

RESULTS

Of 116 patients with MRP, 16 patients (male 8; mean age-65.5 years) had IPH on their initial MRI. For diagnosing neoplastic hematoma, the sensitivity, specificity, PPV and NPV for increased CBF and CBV were 100%, 88.9%, 87.5%, and 100%; for peripheral linear enhancement were 100%, 28.6%, 50%, 100% and for nodular enhancement were 85.7%, 77.8%, 75% and 12.5%, respectively. The combination of peripheral linear enhancement and increased CBF and CBV showed 100% sensitivity, specificity, PPV and NPV.

CONCLUSION

In our small series, the combination of peripheral linear enhancement and increased CBF and CBV showed 100% sensitivity, specificity, PPV and NPV for diagnosing a neoplastic hematoma. These findings need to be validated in a larger study.

Discrimination of Tumorous Intracerebral Hemorrhage from Benign Causes Using CT Densitometry

BACKGROUND AND PURPOSE

Differentiation of tumorous intracerebral hemorrhage from benign etiology is critical in initial treatment plan and prognosis. Our aim was to investigate the diagnostic value of CT densitometry to discriminate tumorous and nontumorous causes of acute intracerebral hemorrhage.

MATERIALS AND METHODS

This retrospective study included 110 patients with acute intracerebral hemorrhage classified into 5 groups: primary intracerebral hemorrhage without (group 1) or with antithrombotics (group 2) and secondary intracerebral hemorrhage with vascular malformation (group 3), brain metastases (group 4), or primary brain tumors (group 5). The 5 groups were dichotomized into tumorous (groups 4 and 5) and nontumorous intracerebral hemorrhage (groups 1-3). Histogram parameters of hematoma attenuation on nonenhanced CT were compared among the groups and between tumorous and nontumorous intracerebral hemorrhages. With receiver operating characteristic analysis, optimal cutoffs and area under the curve were calculated for discriminating tumorous and nontumorous intracerebral hemorrhages.

RESULTS

Histogram analysis of acute intracerebral hemorrhage attenuation showed that group 1 had higher mean, 5th, 25th, 50th, and 75th percentile values than groups 4 and 5 and higher minimum and 5th percentile values than group 2. Group 3 had higher 5th percentile values than groups 4 and 5. After dichotomization, all histogram parameters except maximum and kurtosis were different between tumorous and nontumorous intracerebral hemorrhages, with tumors having lower cumulative histogram parameters and positive skewness. In receiver operating characteristic analysis, 5th and 25th percentile values showed the highest diagnostic performance for discriminating tumorous and nontumorous intracerebral hemorrhages, with 0.81 area under the curve, cutoffs of 34 HU and 44 HU, sensitivities of 65.6% and 70.0%, and specificities of 85.0% and 80.0%, respectively.

CONCLUSIONS

CT densitometry of intracerebral hemorrhage on nonenhanced CT might be useful for discriminating tumorous and nontumorous causes of acute intracerebral hemorrhage.

Dual-energy CT in the evaluation of intracerebral hemorrhage of unknown origin: differentiation between tumor bleeding and pure hemorrhage

BACKGROUND AND PURPOSE

Detection of underlying tumor in patients with unknown-origin acute ICH may be difficult because acute hematoma may mask enhancement of tumor on postcontrast CT. We intended to investigate the clinical utility of DECT in differentiating tumor bleeding from pure ICH.

MATERIALS AND METHODS

Using a dual-source CT scanner, we obtained TNC single-energy and postcontrast DECT scans for 56 patients with unknown-origin spontaneous ICH. From the 2 sets of postcontrast DECT images obtained with different tube energy, EA (equivalent to conventional postcontrast CT), VNC, color-coded iodine overlay, fusion images of iodine overlay and VNC images were produced. The diagnostic performances of fusion, EA, and combined EA and TNC images for detecting underlying tumors were compared.

RESULTS

Of the 56 patients, 17 had primary or metastatic tumors (18 lesions) and 39 had nontumorous ICH. The sensitivities of fusion, EA, and combined EA and TNC images for detecting brain tumors were 94.4%, 61.1%, and 66.7%, respectively, and their specificities were 97.4%, 92.3%, and 89.7%, respectively. The areas under the ROC curves were 0.964, 0.786, and 0.842, respectively. Overall, the diagnostic performance of fusion images was significantly superior to EA (P = .006) and combined EA and TNC (P = .011) images.

CONCLUSIONS

DECT may be useful in detecting underlying tumors in patients with unknown-origin ICH.

Differential diagnosis of nontraumatic intracerebral hemorrhage

A wide variety of nontraumatic pathologies can result in intracerebral hemorrhage (ICH). Primary causes such as arterial hypertension or cerebral amyloid angiopathy can be differentiated from secondary pathologies, such as neoplasms, arterio-venous malformations, coagulopathies, hemorrhagic ischemic strokes, and cerebral venous and sinus thrombosis.Here, the authors first provide some general information on epidemiology, clinical presentation, and imaging appearance of ICHs followed by a detailed discussion of the different underlying pathologic entities and their imaging presentation.

Imaging of hemorrhagic stroke

Neuroimaging by CT or MR is necessary for the detection of hemorrhagic stroke and provides important data regarding the cause of stroke. Serial changes in the CT and MR appearance of hematoma attributable to temporal evolution must be assessed to assure accurate diagnosis. Emerging evidence suggests that the use of MR imaging alone may be adequate for identifying hemorrhage in acute stroke patients and that GRE MR imaging is superior to both CT and conventional spin-echo MR imaging sequences for the detection of chronic microbleeds and hemorrhagic conversion of infarction.

Hemorrhagic stroke

Neuroimaging by CT or MR imaging is necessary for the identification of hemorrhagic stroke and provides information about its cause. The appearance of intracranial hematoma (ICH) on CT and MR imaging evolves over time and must be understood to facilitate accurate diagnosis. The cause of ICH varies by location. New evidence suggests that MR imaging alone may be adequate to identify hemorrhagic stroke in the acute setting, and that MR imaging is superior to CT for identification of chronic microbleeds and hemorrhagic conversion of infarction.

Cerebral metastasis from angiosarcoma of the aortic wall: case report

BACKGROUND

Primary or metastatic cerebral angiosarcoma is extremely rare, and only limited cases have been reported. The authors here describe a case of angiosarcoma, which was initially identified and diagnosed by the cerebral metastatic lesion; later examinations suggested that the primary site was the abdominal aorta.

CASE DESCRIPTION

A 53-year-old man, who had suffered an abdominal aortic aneurysm 2 months earlier, experienced a sudden onset of left-sided hemifacial convulsion and dysarthric speech. Computed tomography (CT) showed a hemorrhagic mass lesion with perifocal edema in the right frontal lobe. Magnetic resonance imaging (MRI) showed a regionally marked hypointensity in the mass lesion on both T1- and T2-weighted images, which might suggest hemosiderin deposition. The tumor was removed in its entirety. Pathologic examination revealed an old hematoma with a hemosiderin deposit containing markedly atypical tumor cells, and angiosarcoma was diagnosed. Resection of the abdominal aortic aneurysm and iliac bone biopsy were performed and angiosarcoma was recognized in each surgical specimen. Based on clinical and pathologic findings, the primary site was considered to be the abdominal aorta.

CONCLUSIONS

Clinicians should be aware of this rare histologic type of tumor. Unique MRI findings such as those obtained in our case might be useful for differentiating this condition from other intracranial neoplasms.

Spontaneously T1-hyperintense lesions of the brain on MRI: a pictorial review

In this work, the brain lesions that cause spontaneously hyperintense T1 signal on MRI were studied under seven categories. The first category includes lesions with hemorrhagic components, such as infarct, encephalitis, intraparenchymal hematoma, cortical contusion, diffuse axonal injury, subarachnoid hemorrhage, subdural and epidural hematoma, intraventricular hemorrhage, vascular malformation and aneurysm, and hemorrhagic neoplasm. The second category includes protein-containing lesions, such as colloid cyst, craniopharyngioma, Rathke's cleft cyst, and atypical epidermoid. The third category includes lesions with fatty components, such as lipoma, dermoid, and lipomatous meningioma. Lesions with calcification or ossification, such as endocrine-metabolic disorder, calcified neoplasm, infection, and dural osteoma, constitute the fourth category, whereas the fifth category includes lesions with other mineral accumulation, such as acquired hepatocerebral degeneration and Wilson disease. The sixth category includes melanin-containing lesions, such as metastasis from melanoma and leptomeningeal melanosis. The last category is the miscellaneous group, which includes ectopic neurohypophysis, chronic stages of multiple sclerosis, and neurofibromatosis type I. The above-mentioned lesions are presented with their typical T1-hyperintense images, and the underlying reasons for those appearances in magnetic resonance imaging are discussed.

Pontine malignant astrocytoma with hemorrhagic onset--case report

A 7-year-old boy presented with acute onset of left hemiparesis and headache, followed by disturbance of consciousness. Neuroimaging studies showed pontine hemorrhage. Surgery was performed to remove a massive hematoma. Histological examination of the wall revealed anaplastic astrocytoma. Postoperative radiation therapy and several types of chemotherapy were administered. However, the tumor recurred and he died 9 months after onset. Hemorrhagic onset of pontine glioma is rare and carries an extremely poor prognosis.

Neuroimaging of stroke: a review

Advances in neuroimaging technology during the past 30 years have resulted in a virtual explosion in the amount of pathologic information that can be obtained in the clinical stroke setting. This neuroimaging revolution has led to a much better understanding of cerebrovascular and tissue pathology, creating a wide array of opportunities for acute treatment and secondary prevention. Advances include early and accurate detection of ischemic and infarcted tissue and the ability to reveal hypoperfused tissue at risk. Clinicians are increasingly able to noninvasively detect embolic and atherothrombotic intravascular lesions. Vascular lesions associated with stroke can be characterized through endovascular neuroimaging techniques and repaired by various means. In this article, we provide an overview and update on the various techniques used in the neuroimaging of stroke and intracranial hemorrhage, including computed tomography, magnetic resonance imaging, ultrasound, and catheter angiography. We outline the specific role of each modality in clinical practice.

Magnetic resonance imaging of pediatric brain tumors: state of the art

Over the past 25 years, magnetic resonance imaging (MRI) has developed into the primary imaging tool for evaluation of the central nervous system. MRI is the essential imaging study in the twenty-first century for the evaluation of the child with a brain tumor for initial preoperative diagnosis, treatment planning and image-guided therapies. This article provides an overview of the locations and MRI features of common pediatric tumors of childhood.

Magnetic resonance imaging in temporal lobe epilepsy: usefulness for the etiological diagnosis of temporal lobe epilepsy

With improvement in magnetic resonance (MR) imaging techniques, the ability to identify lesions responsible for temporal lobe epilepsy has increased. MR imaging has also enabled the in vivo diagnosis of hippocampal sclerosis. Brain tumors are responsible for 2-4% of epilepsies in adult population and 10-20% of medically intractable epilepsy. The sensitivity of MR imaging in the diagnosis of tumors and other lesions of the temporal lobe (vascular malformations, etc.) is around 90%. Both hippocampal sclerosis and other temporal lobe lesions are amenable to surgical therapy with excellent postsurgical seizure outcome. In this article, we characterize and underline distinguishing features of the different pathological entities. We also suggest an approach to reviewing the MR images of an epileptic patient.

The value of MRI in angiogram-negative intracranial haemorrhage

In one year, cerebral angiograms were performed for intracranial haemorrhage (ICH) on 334 patients. No cause for haemorrhage could be identified in 41 (12%), 30 of whom had predominantly subarachnoid (SAH) and 11 predominantly parenchymal haemorrhage (PH). These patients were prospectively examined by cranial MRI 1-6 weeks after the ictus. The MRI studies were positive in 7 patients (17%). In the 30 patients examined after SAH, 2 studies were positive, showing an aneurysm in one case and a brain stem lesion of uncertain aetiology in the other. In those examined after PH, cavernous angiomas were shown in 2, a tumour in 1 and a vascular malformation in another; useful diagnostic information was thus obtained in 36% of this group.

Acute intracerebral haematomas: assessment for possible underlying cause with MRI scanning

Forty-seven patients presenting with acute intracerebral haematomas between 1989 and 1992 were retrospectively examined to assess the role of Magnetic Resonance Imaging (MRI) in identifying any underlying lesion. None had any prior known intracerebral pathology. Magnetic resonance imaging scans were done on a 0.5 T unit. Ten patients with an average age of 35 years had angiographically occult vascular malformations (AOVM) found by MRI (one with biopsy confirmation). One of three cases of glioma, three of three cases with secondary tumour, one case of superior sagittal sinus thrombosis with haemorrhagic infarction, one of two cases of venous angioma and one case of arteriovenous malformation were detected by MRI. Progress computed tomography scans discovered two cases of glioma and angiography found a venous angioma and an arterial aneurysm, all undetected by MRI. It is concluded that MRI scanning is helpful in detecting underlying AOVM as a cause of intracerebral haemorrhage but its role in imaging haemorrhagic tumours remains unclear.

Accelerated methaemoglobin formation: potential pitfall in early postoperative MRI

Postoperative magnetic resonance imaging (MRI) of glioblastomas to assess residual tumour should be performed within the first 4 days following surgery. Early methaemoglobin formation near the resection site may mimic residual tumour if only gadolinium-DTPA-enhanced images are obtained. In a prospective study 24 of 54 patients (44%) showed well-defined areas of increased signal intensity on unenhanced T1-weighted images performed soon after surgery. By in vitro experiments we showed that hydrogen peroxide used in neurosurgery as a styptic agent accelerates formation of methaemoglobin when added to whole blood samples.

Haemorrhagic cerebral metastases from malignant testicular teratoma

Cerebral metastases from malignant testicular teratoma may show complex appearances with magnetic resonance imaging (MRI), which are consistent with changes resulting from repeated haemorrhage. Haemorrhage causes enlargement and symptomatic progression of cerebral lesions, and this can occur even when extracranial disease or other cerebral lesions remain static.

Lobar intracerebral hemorrhage. A clinical, radiographic, and pathological study of 29 consecutive operated cases with negative angiography

The authors operated consecutively on 50 patients with lobar intracerebral hemorrhage during a prospectively designed study period from January, 1986, to March, 1990. They investigated the correlations between the underlying causes and the clinicoradiographic features in 29 patients who showed no angiographic vascular abnormalities, in order to elucidate the operative indication for such cases. Patients with ruptured saccular aneurysm or trauma were not included in this study. There were 15 males and 14 females, ranging in age from 7 to 76 years (mean 52.4 years). Histological diagnoses of the surgical specimens were as follows: vascular malformation in nine cases (arteriovenous malformation (AVM) in six and cavernous malformation in three), microaneurysm in 11, cerebral amyloid angiopathy in six, and brain tumor in two; in the remaining case the cause was not verified histologically. The underlying cause was determined in 96.5% of cases. The mean patient age was lowest in the cavernous malformation group (27.0 years), followed by the AVM (45.8 years), microaneurysm (59.8 years), and cerebral amyloid angiopathy (70.0 years) groups. Four patients with vascular malformation (three AVM's and one cavernous malformation) had previous episodes of bleeding at the same site, whereas none of those with microaneurysms or cerebral amyloid angiopathy had such episodes. On computerized tomography (CT) scans, the round to oval hematoma was related to the presence of an AVM or cavernous malformation in contrast to microaneurysms and cerebral amyloid angiopathy. Upon infusion of contrast material, variable enhancement was seen in five (two AVM's and three cavernous malformations) of the nine vascular malformations while no enhancement was noted in any patient with microaneurysm or cerebral amyloid angiopathy at the acute stage. Subarachnoid extension of the hematoma was associated with cerebral amyloid angiopathy significantly more frequently than with AVM's (p less than 0.05) and microaneurysms (p less than 0.01). The results suggest that clinicoradiographic pictures in cases with negative angiography are quite different among the three major pathological categories; namely, vascular malformation (AVM and cavernous malformation), microaneurysm, and cerebral amyloid angiopathy. It is suggested that the underlying etiology of a given lobar intracerebral hemorrhage with negative angiography may be predicted by a combination of patient age, history of previous bleeding at the same site, hematoma shape, and subarachnoid extension of the hematoma on CT scans. Based upon these findings, the authors discuss operative indications for such cases.