Computed tomography in the diagnosis of malignant brain tumours: do all patients require biopsy?

Correlation of (18)F-fluoroethyl tyrosine positron-emission tomography uptake values and histomorphological findings by stereotactic serial biopsy in newly diagnosed brain tumors using a refined software tool

Background

Magnetic resonance imaging (MRI) is the standard neuroimaging method to diagnose neoplastic brain lesions, as well as to perform stereotactic biopsy surgical planning. MRI has the advantage of providing structural anatomical details with high sensitivity, though histological specificity is limited. Although combining MRI with other imaging modalities, such as positron-emission tomography (PET), has proven to increment specificity, exact correlation between PET threshold uptake ratios (URs) and histological diagnosis and grading has not yet been described.

Objectives

The aim of this study was to correlate exactly the histopathological criteria of the biopsy site to its PET uptake value with high spatial resolution (mm³), and to analyze the diagnostic value of PET using the amino acid O-(2-[¹⁸F]fluoroethyl)-l-tyrosine (¹⁸F-FET) PET in patients with newly diagnosed brain lesions in comparison to histological findings obtained from stereotactic serial biopsy.

Patients and methods

A total of 23 adult patients with newly diagnosed brain tumors on MRI were enrolled in this study. Subsequently to diagnoses, all patients underwent a ¹⁸F-FET PET-guided stereotactic biopsy, using an original newly developed software module, which is presented here. Conventional MRI, stereotactic computed tomography series, and ¹⁸F-FET PET images were semiautomatically fused, and hot-spot detection was performed for target planning. UR was determined using the uptake value from the biopsy sites in relation to the contralateral frontal white matter. UR values ≥1.6 were considered positive for glioma. High-grade glioma (HGG) was suspected with URs ≥3.0, while low-grade glioma (LGG) was suspected with URs between 1.6 and 3.0. Stereotactic serial biopsies along the trajectory at multiple sites were performed in millimeter steps, and the FET URs for each site were correlated exactly with a panel of 27 different histopathological markers. Comparisons between FET URs along the biopsy trajectories and the histological diagnoses were made with Pearson product-moment correlation coefficients. Analysis of variance was performed to test for significant differences in maximum UR between different tumor grades.

Results

A total of 363 biopsy specimens were taken from 23 patients by stereotactic serial biopsies. Histological examination revealed eight patients (35%) with an LGG: one with a World Health Organization (WHO)-I lesion and seven with a WHO-II lesion. Thirteen (57%) patients revealed an HGG (two with a WHO-III and three with a WHO-IV tumor), and two patients (9%) showed a process that was neither HGG nor LGG (group X or no-grade group). The correlation matrix between histological findings and the UR revealed five strong correlations. Low cell density in tissue samples was found to have a significant negative correlation with the measured cortical uptake rate (r=−0.43, P=0.02), as well as moderate cell density (r=−0.48, P=0.02). Pathological patterns of proliferation (r=0.37, P=0.04), GFAP (r=0.37, P=0.04), and Olig2 (r=0.36, P=0.05) showed a significant positive correlation with cortical URs. Analysis of variance tests showed a significant difference between the LGG and the HGG groups (F=8.27, P<0.002), but no significant differences when differentiating between the X group and the HGG (P=0.2)/LGG (P=0.8) groups, nor between the no-grade group and the WHO-I group.

Conclusion

¹⁸F-FET PET is a valuable tool, as it allows the differentiation of HGGs from LGGs. Its use is not limited to preoperative evaluation; it may also refine biopsy targeting and improve tumor delimitation for radiotherapy. Histology is still necessary, and remains the gold standard for definitive diagnosis of brain lesions.

Indicators of Functional Status for Primary Malignant Brain Tumour Patients

Background:

We compared the functional status and survival time of patients with malignant gliomas.

Methods:

This retrospective review included 143 patients diagnosed with malignant gliomas. Patients were grouped according to histopathological diagnosis. To measure functional status, patients were assigned a Karnofksy performance status (KPS) score at the time of presentation and at one, three, six, nine, 12 months and yearly intervals thereafter. Data were analyzed using descriptive methods as well as Kruskal-Wallis tests, Chi-square tests, Log-Rank tests and Cox’s proportional hazards modeling.

Results:

Eighty-four patients were male. The median age of patients was 63 years. One hundred and seven patients had a histopathological diagnosis of glioblastoma multiforme, 23 of anaplastic astrocytoma and 13 of anaplastic oligodendroglioma. Twenty-nine patients received aggressive multimodal treatment, 83 received intermediate treatment and the remaining 31 patients received conservative therapy. Significant treatment complications occurred in 33% of patients including four post-operative deaths. The anaplastic oligodendroglioma group had lower mortality and maintained better KPS scores over time, as did patients receiving full treatment. The most significant prognostic factors for functional status included age, pretreatment KPS, and type of treatment received. The most significant factors associated with time until death included age, severity of comorbidities, pretreatment KPS, presence of confusion, histopathological diagnosis and type of treatment received.

Conclusion:

In patients with malignant gliomas, younger age, better functional status at presentation and aggressive multimodal treatment were associated with improved longer-term functional status and survival. Confirmation of the effect of multimodal treatment on patient functional status would require a randomised controlled clinical trial.

Factors predictive of abnormal results for computed tomography of the head in horses affected by neurologic disorders: 57 cases (2001-2007)

OBJECTIVE

To determine neurologic indications associated with abnormal results for computed tomography (CT) imaging of the head of horses affected by neurologic disorders.

DESIGN

Retrospective case series.

ANIMALS

57 horses.

PROCEDURES

Signalment, history, clinical abnormalities, and clinicopathologic findings were obtained from medical records of horses examined because of neurologic disorders, and precontrast and postcontrast CT images of the head were reviewed. Data were analyzed by use of univariate and multivariate logistic regression.

RESULTS

For a horse with abnormal mentation, odds of having abnormal results for CT imaging of the head was 30 times (95% confidence interval [CI], 2.36 to 374.63) the odds for a similar horse without abnormal mentation. For a horse with cranial nerve deficits, odds of having abnormal results for CT imaging of the head was 11 times (95% CI, 1.00 to 127.96) the odds for a similar horse without cranial nerve deficits. For a horse with seizure-like activity, odds of having abnormal results for CT imaging of the head was 0.05 times (95% CI, 0 to 0.90) the odds for a similar horse without seizures.

CONCLUSIONS AND CLINICAL RELEVANCE

These results suggested that alterations in consciousness and cranial nerve deficits were strong predictors of abnormal CT findings for the head of affected horses. Thus, CT can be a useful complementary diagnostic test in horses with these neurologic deficits. In contrast, alternative diagnostic tests (eg, electroencephalography and magnetic resonance imaging) should be considered in horses with seizure-like activity that do not have head trauma or cranial nerve deficits.

PET imaging in the surgical management of pediatric brain tumors

OBJECTIVE

The present article illustrates whether positron-emission tomography (PET) imaging may improve the surgical management of pediatric brain tumors (PBT) at different steps.

MATERIALS AND METHODS

Among 400 consecutive PBT treated between 1995 and 2005 at Erasme Hospital, Brussels, Belgium, we have studied with (18) F-2-fluoro-2-deoxy-D-glucose (FDG)-PET and/or L-(methyl-(11)C)methionine (MET)-PET and integrated PET images in the diagnostic workup of 126 selected cases. The selection criteria were mainly based on the lesion appearance on magnetic resonance (MR) sequences. Cases were selected when MR imaging showed limitations for (1) assessing the evolving nature of an incidental lesion (n = 54), (2) selecting targets for contributive and accurate biopsy (n = 32), and (3) delineating tumor tissue for maximal resection (n = 40). Whenever needed, PET images were integrated in the planning of image-guided surgical procedures (frame-based stereotactic biopsies (SB), frameless navigation-based resections, or leksell gamma knife radiosurgery).

RESULTS

Like in adults, PET imaging really helped the surgical management of the 126 children explored, which represented about 30% of all PBT, especially when the newly diagnosed brain lesion was (1) an incidental finding so that the choice between surgery and conservative MR follow-up was debated, and (2) so infiltrative or ill-defined on MR that the choice between biopsy and resection was hardly discussed. Integrating PET into the diagnostic workup of these two selected groups helped to (1) take a more appropriate decision in incidental lesions by detecting tumor/evolving tissue; (2) better understand complex cases by differentiating indolent and active components of the lesion; (3) improve target selection and diagnostic yield of stereotactic biopsies in gliomas; (4) illustrate the intratumoral histological heterogeneity in gliomas; (5) provide additional prognostic information; (6) reduce the number of trajectories in biopsies performed in eloquent areas such as the brainstem or the pineal region; (7) better delineate ill-defined PBT infiltrative along functional cortex than magnetic resonance imaging (MRI); (8) increase significantly, compared to using MRI alone, the number of total tumor resection and the amount of tumor tissue removed in PBT for which a total resection is a key-factor of survival; (9) target the resection on more active areas; (10) improve detection of tumor residues in the operative cavity at the early postoperative stage; (11) facilitate the decision of early second-look surgery for optimizing the radical resection; (12) improve the accuracy of the radiosurgical dosimetry planning.

CONCLUSIONS

PET imaging may improve the surgical management of PBT at the diagnostic, surgical, and post-operative steps. Integration of PET in the clinical workup of PBT inaugurates a new approach in which functional data can influence the therapeutic decision process. Although metabolic information from PET are valid and relevant for the clinical purposes, further studies are needed to assess whether PET-guidance may decrease surgical morbidity and increase children survival.

Combined use of 18F-fluorodeoxyglucose and 11C-methionine in 45 positron emission tomography—guided stereotactic brain biopsies

Object. The aim of this study was to compare the contribution of the tracers 11C-methionine (Met) and 18F-fluorodeoxyglucose (FDG) in positron emission tomography (PET)—guided stereotactic brain biopsy.

Methods. Forty-five patients underwent combined Met-PET and FDG-PET studies associated with computerized tomography (CT)— or magnetic resonance (MR)—guided stereotactic biopsy. Each patient presented with a lesion that was in proximity to the cortical or subcortical gray matter. The Met-PET and FDG-PET scans were analyzed to determine which tracer offers the best information to guide at least one stereotactic biopsy trajectory. Histologically based diagnoses were rendered in all patients (39 tumors, six nontumorous lesions) and biopsies were performed in all tumors with the aid of PET guidance. When tumor FDG uptake was higher than that in the gray matter (18 tumors), FDG was used for target definition. When FDG uptake was absent or equivalent to that in the gray matter (21 tumors), Met was used for target definition. Parallel review of all histological and imaging data showed that all tumors had an area of abnormal Met uptake and 33 had abnormal FDG uptake. All six nontumorous lesions had no Met uptake and biopsies were performed using CT or MR guidance only. All tumor trajectories had an area of abnormal Met uptake; all nondiagnostic trajectories in tumors had no abnormal Met uptake.

Conclusions. When FDG shows limitations in target selection, Met is a good alternative because of its high specificity in tumors. Moreover, in the context of a single-tracer procedure and regardless of FDG uptake, Met is a better choice for PET guidance in neurosurgical procedures.

Medulloblastoma of the cerebellopontine angle--case report

A 21-year-old male patient presented with a rare cerebellopontine angle medulloblastoma manifesting as cerebellar and long tract involvement signs and symptoms. The clinical and radiological characteristics of the lesion were similar to extraaxial lesions of cerebellopontine angle. The histological diagnosis of the lesion was medulloblastoma. Surgery achieved partial removal and was followed by radiotherapy and chemotherapy. The patient remained well after 18 months. Medulloblastoma of the cerebellopontine angle is a relatively rare clinical entity and may occur as a dural-based extraaxial mass.

Atypical delayed intracranial haematoma following stereotactic biopsy of a right parietal anaplastic oligodendroglioma

The history of a 73-year-old woman with an anaplastic oligodendroglioma is presented, in whom cerebral magnetic resonance imaging (MRI) and brain single-photon emission tomography (SPECT) revealed an intracerebral lesion 17 months before, which was misinterpreted as cerebral infarction. Stereotactic biopsy confirmed the diagnosis, but 4 days after biopsy an unexpected fatal subdural and intraparenchymal bleeding occurred on the biopsy site. Neuroradiological aspects in the differential diagnosis of cerebral lesions as well as the role of small silent postbiopsy haematoma concerning further clinical deterioration are discussed.

CT-guided brain biopsy using a modified Pelorus Mark III stereotactic system: experience with 50 dogs

This report describes the results of CT-guided stereotactic brain biopsies performed on 50 consecutive dogs using a modified Pelorus Mark III Stereotactic System. Based on available histopathologic samples (stereotactic biopsy [n = 50], surgery [n = 17], necropsy [n = 9]) the patient population consisted of 34 dogs with primary brain tumors, 2 with invasive nasal adenocarcinomas, and 13 with non-neoplastic brain lesions. Brain tissue was not obtained from one dog. In 22 dogs a final diagnosis was made from tissue subsequently obtained from surgical resection or at necropsy. The final diagnosis was in agreement with the stereotactic biopsy diagnosis in 20 of these 22 dogs. In 17 other dogs without follow-up, stereotactic biopsy provided a diagnosis of a specific primary brain tumor subtype. Postoperative complications associated with the biopsy procedure were assessed in 41 dogs. The other 9 dogs either went directly to surgery (n = 7) or were killed (n = 2) immediately after the biopsy procedure. Thirty-six dogs recovered without apparent clinical complications. Postoperative clinical complications in the remaining 5 dogs included transient epistaxis (1 dog), transient exacerbation of cerebellar signs (1 dog), obtundation progressing to coma (1 dog), and medically uncontrollable seizures (2 dogs). The latter 3 dogs with severe neurologic complications all had large primary brain tumors and had been receiving high doses of phenobarbital and glucocorticoids to control seizures at the time of biopsy. These results suggest that this CT-guided biopsy procedure can provide an accurate pathologic diagnosis of brain lesions detected by CT and MR neuroimaging. Further refinement of both technique and case selection is expected to reduce the rate of clinical complications and to improve the accuracy of the procedure.

Evaluation of malignancy in ring enhancing brain lesions on CT by thallium-201 SPECT

OBJECTIVE

To investigate patients with cystic enhancing lesions on CT and to determine whether thallium-201 (201Tl) SPECT adds to further preoperative information in differential diagnosis between gliomas and abscesses.

METHODS

Twenty one patients with cystic ring enhancing CT findings were studied and uptake indices were compared with CT enhancement volumes, histopathology, and survival times.

RESULTS

Fourteen high grade gliomas, three low grade gliomas, and four abscesses were found. Uptake was higher in the highly malignant glioma group (median thallium index (TI)=2.1), than in the low grade glioma group (median TI=1.4) or among the abscesses (median TI=1.6). Overlapping indices were found between high and low malignant cystic gliomas as well as between either one of the glioma groups and the infectious lesions, and there were no significant differences between groups. There was a level at the value 2, where TI > or = 2 correlated with tumour diagnosis. One low grade tumour had an extremely high index and a very high enhancement volume. Indices correlated significantly with CT enhancement volumes (P=0.005). There was no significant correlation between Tl indices and patient survival times among the high grade gliomas. One patient with a highly malignant tumour but low Tl uptake < 2, had a survival > five years.

CONCLUSIONS

It is concluded that high 201Tl uptake in enhancing cystic lesions is an indicator of highly malignant glioma. However, the differentiation between the high malignant gliomas and abscesses or low malignant gliomas by 201TL SPECT is only partial with an overlap between these groups.

Prediction of posterior fossa tumor type in children by means of magnetic resonance image properties, spectroscopy, and neural networks

Recent studies have explored characteristics of brain tumors by means of magnetic resonance spectroscopy (MRS) to increase diagnostic accuracy and improve understanding of tumor biology. In this study, a computer-based neural network was developed to combine MRS data (ratios of N-acetyl-aspartate, choline, and creatine) with 10 characteristics of tumor tissue obtained from magnetic resonance (MR) studies, as well as tumor size and the patient's age and sex, in hopes of further improving diagnostic accuracy. Data were obtained in 33 children presenting with posterior fossa tumors. The cases were analyzed by a neuroradiologist, who then predicted the tumor type from among three categories (primitive neuroectodermal tumor, astrocytoma, or ependymoma/other) based only on the data obtained via MR imaging. These predictions were compared with those made by neural networks that had analyzed different combinations of the data. The neuroradiologist correctly predicted the tumor type in 73% of the cases, whereas four neural networks using different datasets as inputs were 58 to 95% correct. The neural network that used only the three spectroscopy ratios had the least predictive ability. With the addition of data including MR imaging characteristics, age, sex, and tumor size, the network's accuracy improved to 72%, consistent with the predictions of the neuroradiologist who was using the same information. Use of only the analog data (leaving out information obtained from MR imaging), resulted in 88% accuracy. A network that used all of the data was able to identify 95% of the tumors correctly. It is concluded that a neural network provided with imaging data, spectroscopic data, and a limited amount of clinical information can predict pediatric posterior fossa tumor type with remarkable accuracy.

Prediction of posterior fossa tumor type in children by means of magnetic resonance image properties, spectroscopy, and neural networks

Recent studies have explored characteristics of brain tumors by means of magnetic resonance spectroscopy (MRS) to increase diagnostic accuracy and improve understanding of tumor biology. In this study, a computer-based neural network was developed to combine MRS data (ratios of N-acetyl-aspartate, choline, and creatine) with 10 characteristics of tumor tissue obtained from magnetic resonance (MR) studies, as well as tumor size and the patient's age and sex, in hopes of further improving diagnostic accuracy.

Data were obtained in 33 children presenting with posterior fossa tumors. The cases were analyzed by a neuroradiologist, who then predicted the tumor type from among three categories (primitive neuroectodermal tumor, astrocytoma, or ependymoma/other) based only on the data obtained via MR imaging. These predictions were compared with those made by neural networks that had analyzed different combinations of the data. The neuroradiologist correctly predicted the tumor type in 73% of the cases, whereas four neural networks using different datasets as inputs were 58 to 95% correct. The neural network that used only the three spectroscopy ratios had the least predictive ability. With the addition of data including MR imaging characteristics, age, sex, and tumor size, the network's accuracy improved to 72%, consistent with the predictions of the neuroradiologist who was using the same information. Use of only the analog data (leaving out information obtained from MR imaging), resulted in 88% accuracy. A network that used all of the data was able to identify 95% of the tumors correctly. It is concluded that a neural network provided with imaging data, spectroscopic data, and a limited amount of clinical information can predict pediatric posterior fossa tumor type with remarkable accuracy.

Stereotactic brain biopsy guided by positron emission tomography (PET) with [F-18]fluorodeoxyglucose and [C-11]methionine

The aim of the present study was to compare the contribution of the labelled tracers [C-11]methionine (Met) and [F-18]-fluorodeoxyglucose (FDG) in positron emission tomography (PET)-guided stereotactic biopsy of non resectable brain lesions. Twenty-five patients underwent combined Met-PET-, FDG-PET- and computerized tomography (CT)- or magnetic resonance (MR)-guided stereotactic biopsy according to a previously described technique for stereotactic FDG-PET. Met-PET and FDG-PET images were analyzed to determine which tracer offers the best information to guide at least one stereotactic biopsy trajectory. Histological diagnosis was obtained in all patients (23 tumours and 2 non-tumorous lesions). All tumours had an area of abnormal Met uptake and were biopsied under PET-guidance. FDG uptake in the tumour was higher than in the grey matter and was used for target selection in 12 of 23 tumours. Eleven of them were located in the basal ganglia or the brainstem. Met was used for target selection in 11 of 23 tumours where there was no FDG uptake or where FDG uptake was equivalent to that of the grey matter. Ten of them were located in the cortex. Two nontumoral lesions had no Met uptake and were biopsied under CT- or MR-guidance only. Forty-three out of 53 stereotactic trajectories obtained in these 25 patients were based on PET-defined targets and had an area of abnormal Met uptake. These trajectories always yielded a diagnosis of tumour. Moreover, all tumorous trajectories had an area of abnormal Met uptake. Finally, all non-diagnostic trajectories (n = 4) were CT/MR-defined because there was no area of abnormal Met uptake. These results suggest that patients who can benefit the most from Met-PET guidance could be selected pre-operatively. In conclusion, this work shows that Met is a good alternative to FDG for target selection in PET-guided stereotactic brain biopsy.

Management of primary malignant brain tumours

Images

Use of positron emission tomography (PET) in stereotactic conditions for brain biopsy

In order to take advantage of the metabolic information provided by positron emission tomography (PET) in cases of brain tumour, we have developed a technique to integrate PET images routinely in the planning of stereotactic brain biopsy. We used stereotactic PET with [18F]-labelled fluorodeoxyglucose (PET-FDG) in 38 patients undergoing brain biopsy. To evaluate the contribution of PET-FDG in guiding brain biopsy, we analyzed the diagnosis provided by the 78 stereotactic trajectories obtained in these patients. We found that stereotactic PET-FDG seemed to provide more information in cases of anaplastic astrocytomas and glioblastomas than in low-grade gliomas. Our results also show that biopsy trajectories performed in areas where increased FDG uptake is found within the lesion boundaries always provide interpretable specimens; this was not the case for trajectories guided by CT only. Therefore, the routine integration PET-FDG in the planning of stereotactic brain biopsy may lead to a reduction in sampling. Recently, we also tested consecutive stereotactic PET with [11C]-labelled methionine (PET-Met) and PET-FDG. This technique allowed us to compare accurately the tumoural glucose metabolism and protein synthesis. Our results suggest that stereotactic PET may increase the diagnostic yield of brain biopsy and may improve the understanding of PET in neuro-oncology.

Diagnostic yield of stereotactic brain biopsy guided by positron emission tomography with [18F]fluorodeoxyglucose

The aim of the present study was to determine whether routine integration of positron emission tomography (PET) with 18F-labeled fluorodeoxyglucose (FDG) in the planning of stereotactic brain biopsy increases the technique's diagnostic yield. Forty-three patients underwent combined FDG-PET- and computerized tomography (CT)-guided stereotactic biopsy of intracranial lesions according to a previously described technique. In 36 patients, an area of abnormal FDG uptake was used to guide at least one stereotactic biopsy trajectory. A total of 90 stereotactic trajectories were performed; among them, 55 were based on FDG-PET-defined targets and 35 were based on CT-defined targets. Histological diagnosis was obtained in all patients, but six of the 90 trajectories were nondiagnostic; all six were based on targets defined by CT only. Differences between the diagnostic yield of trajectories based on FDG-PET-defined targets and those based on CT-defined targets were statistically significant in patients with contrast-enhanced lesions, but not in patients with nonenhancing lesions. These results support the view the FDG-PET may contribute to the successful management of brain tumor patients requiring stereotactic biopsy. Because no significant increase in discomfort or morbidity related to the technique was found, it is suggested that the development of similar techniques integrating PET data in the planning of stereotactic biopsy should be considered by centers performing stereotactic surgery and having access to PET technology.

Thallium imaging for brain tumors with results measured by a semiquantitative index and correlated with histopathology

BACKGROUND

The optimal management of patients with brain tumors requires knowledge of the tumor characteristics upon presentation and the discovery of recurrence after therapy. Thallium-201 (Tl-201) chloride has shown varying uptake in tumors, depending on their viability and the type and degree of malignancy. This study explores the diagnostic potential of thallium imaging in patients with brain tumors.

METHODS

Forty-three Tl-201 single photon emission computed tomographic scintigrams were performed on 40 patients with intracranial neoplasms, nearly equally divided between patients with no prior treatment and patients who had prior treatment and were suspected to have recurrent tumor and/or radiation necrosis. A thallium tumor index was calculated as the ratio of counts for a region of interest drawn in the lesion area and its mirror image in normal brain tissue. A two-tailed Student's t test was performed to compare the thallium index and histopathologic findings.

RESULTS

A value of 1.5 for the thallium tumor index allowed for the best correlation between the prediction of malignancy and the histopathologic results. In the pretreatment group, a thallium tumor index greater than 1.5 correlated with high grade malignancy, and less than 1.5 correlated with either a well differentiated astrocytoma or benign cyst. In the posttreatment group, a thallium tumor index greater than 1.5 correlated with recurrent and/or residual malignant tumor.

CONCLUSIONS

For those patients undergoing initial evaluation, the thallium study can help in the differential diagnosis of an intracranial mass lesion and offers confirmation of results of biopsy. For those patients who already have received treatment, the study can be used to detect recurrent or residual tumor.

The management of histologically unverified presumed cerebral gliomas with radiotherapy

PURPOSE

To define the natural history, and prognostic factors of patients with histologically unverified presumed gliomas diagnosed on CT or MR imaging, and treated with external beam radiotherapy.

METHODS AND MATERIALS

Retrospective review of 111 adults with histologically unverified presumed cerebral glioma treated with radiotherapy between 1974 and 1990. Using CT or MRI criteria alone 41 were presumed low grade, 63 high grade gliomas and 7 were unclassified. Survival results were compared to a cohort of 82 adults with histologically verified low grade gliomas treated over the same period with surgery and radiotherapy.

RESULTS

The 5 year survival probability of the whole cohort was 31%. Age, performance status, and the degree of contrast enhancement were independent prognostic factors for survival. Patients with presumed low grade glioma had a 5 year survival of 41% compared to 52% for patients with verified low grade glioma. After correction for prognostic factors no significant difference was found in the survival between patients with verified and unverified low grade tumors. One of 15 cases with subsequent histology, obtained at autopsy or salvage surgery, had nonglial pathology.

CONCLUSION

Patients diagnosed on the basis of clinical features and imaging as having presumed glioma have similar natural history and clinical behavior after treatment with radiotherapy to those with histologically confirmed gliomas. However, the results should not be taken as justification for avoiding biopsy. A proportion of patients may have nonglial pathology and new more effective treatment strategies for patients with glial tumors can only evolve on the basis of full diagnostic information including pathology.

Is peroperative smear cytology necessary for CT-guided stereotaxic biopsy?

Neuropathology is a relatively scarce resource with uneven geographical distribution, and some surgeons rely on macroscopic appearances of tissue and await later paraffin section histology for the final diagnosis. The effect of the introduction of a peroperative cytology service has been assessed in a 5-year series of CT-directed stereotaxic biopsies of intracranial mass lesions using a low cost adapted pre-CT stereotaxic frame. The technique has been mastered by 28 different surgeons with varying degrees of neurosurgical expertise and 259 procedures have been performed in 245 patients. Benign lesions were detected in 24 (9.8%) patients, confirming the importance of making a histological diagnosis prior to initiating treatment. Permanent morbidity was 6.5% and mortality 3.3% and morbidity was balanced by an improvement in 19.6% of the patients following the procedure. For the first 142 patients no peroperative histological diagnosis was available and a diagnostic rate of 86.6% was achieved. For the last 103 patients the availability of peroperative smears improved the diagnostic rate to 94.2% and reduced the number of second biopsies needed for diagnosis from seven to zero. Our series demonstrates the need for peroperative cytology in CT stereotaxic biopsies, and confirms that a complete neuropathology service is a prerequisite for neurosurgical patient care.

CT-guided stereotactic neurosurgery using the Brown-Roberts-Wells system: experience with 125 procedures

Experience with a consecutive series of 125 computerized tomographic (CT) image guided stereotaxic neurosurgical procedures, performed using the Brown-Roberts-Wells (BRW) system is described. Operative objectives included tissue sampling for diagnostic purposes, intra-operative localization of craniotomy flaps and intracerebral lesions, cyst and abscess aspiration and lesion to modulate tremor. A neuropathological diagnosis was possible in 96% of the biopsies, and lesions were precisely localized in all patients undergoing microsurgical stereotaxic craniotomy. Two patients (2.2%) undergoing stereotaxic biopsy died as a result of the procedure and one patient's hemiparesis was permanently worsened (0.8%). In only one of three patients undergoing stereotaxic thalamotomy was tremor abolished. This report confirms that CT image guided stereotaxic neurosurgery is safe, accurate and versatile. There is, however, a moderate incidence (7.2%) of lesser complications that can occur with this type of surgery. These complications, which are emphasized in this paper, are related to both the site of surgery and the neuropathology.

The prognosis of primary intracerebral tumours presenting with epilepsy: the outcome of medical and surgical management

It is not known whether conservative or early aggressive (resective surgery with or without radiotherapy) management is better for tumours presenting with epilepsy. The prognosis of 560 patients with a clinical and CT diagnosis of intrinsic supratentorial tumour was examined retrospectively. Epilepsy was the first symptom in 164 patients. Histological confirmation of diagnosis was available in 391 (70%) of cases. Median survival was 37 months in the group presenting with epilepsy and six months in those presenting with other symptoms (p less than 0.0001). Patients presenting with epilepsy were more likely to have a normal clinical examination, a non-enhancing low density lesion on CT scan and a low grade tumour. From Cox's stepwise proportional hazards model, significant independent variables adversely affecting prognosis were increasing age, focal neurological signs and enhancing CT lesions at diagnosis, non-resective surgery and male sex. Of those presenting with epilepsy 80 patients had surgical treatment within two months of CT diagnosis. The Cox's model failed to identify any beneficial effects for either early resective surgery or radiotherapy. In primary intracerebral tumours with presentations other than epilepsy, resective surgery and radiotherapy were amongst the important factors associated with prolonged survival. Primary intracerebral tumours presenting with epilepsy are relatively benign and their outcome appears to be chiefly determined by clinical factors.

The treatment of primary malignant brain tumours

Images

Stereotactic-endoscopic procedures on processes of the cranial midline

The term "midline tumour" is defined partly from the topographic and from the pathogenetic point of view. Problems of modern imagegenerating procedures in establishing the diagnosis of cerebral midline lesions are described. The role of stereotactic diagnostic and therapeutic interventions is emphasized. Stereotactic brain tumour biopsy, installation of shunts and reservoirs under visual control are performed. Interstitial radiotherapy is carried out for low-grade gliomas. As an important innovation, stereotactic procedures are combined with endoscopic techniques. Particular diagnostic and therapeutic difficulties of typical midline tumours such as craniopharyngeoma, germinoma, glioma and primary cerebral lymphoma as a local extension are discussed. A reasonable concept in diagnosis and therapy of cerebral midline lesions is proposed.

Resolution of fluent dysphasia following excision of metastatic carcinoma from the arcuate fasciculus

The effect of therapy on aphasic syndromes in patients with brain tumours is poorly documented. A case in which resection of a metastatic lesion led to resolution of a fluent dysphasia that had not responded to corticosteroid therapy is presented. As well as surgical and neurolinguistic interest this case demonstrates that CT diagnosis of malignant glioma can be erroneous and may lead to sub-optimal treatment.

Therapy and survival of adult patients with intracranial glioma in a defined population

During the 3 years 1978-1980 146 adult patients with intracranial glioma were diagnosed in the Province of Uusimaa in southern Finland. The median survival of all patients was 15 months, of glioblastoma (n = 41) 5.1 months, of anaplastic astrocytoma (n = 29) 12.4 months, of benign grade I-II astrocytoma (n = 30) 93.5 months, of other glioma 82.9 months (n = 27), and of probable glioma 9.8 months (n = 19); 22 patients are still alive 8.9-11.9 years after diagnosis. The patients who were 15-44 years of age at the time of diagnosis survived 75.4 months in the median (n = 58), 45-64 years 10.5 months (n = 61) and 65 years or older 4.8 months (n = 27); 96 patients were operated, 89 received radiotherapy and 34 chemotherapy. According to the proportional hazards' model, follow-up time, age and histological type of tumor were statistically highly significant in explaining differences in survival.

Percutaneous stereotactic brain tumour biopsy and cyst aspiration with a non-invasive frame

A non-invasive Stereoadapter was used for stereotactic CT-guided percutaneous brain biopsy in 18 patients with 16 solid tumours and four cysts. The Stereoadapter was mounted on the patient's head using ear plugs and a nasion support. After the CT study, the Stereoadapter was detached. The target was simulated on a phantom base and a probe carrier attached to the Stereoadapter. For surgery, the Stereoadapter with the probe carrier was remounted to the patient's head. Local anaesthesia was mainly used. Tissue samples were aspirated with a 2 mm diameter Sedan-Nashold biopsy cannula, introduced through a twist drill hole. Conclusive histological/cytological diagnosis was obtained in 16 of the 20 lesions. The new method proved to be reliable and quick. Since the imaging study and the surgery could be separated in time and place, the biopsy procedure was less time-consuming than previous methods of stereotactic biopsy using an invasive frame.