Combination of single-voxel proton MR spectroscopy and apparent diffusion coefficient calculation in the evaluation of common brain tumors

BACKGROUND AND PURPOSE

MR spectroscopy and apparent diffusion coefficient (ADC) calculation have been used frequently for tumor grading and differentiation during the last decade. We evaluated whether the combination of these two techniques can improve the diagnostic effectiveness of MR imaging in patients with brain tumors.

METHODS

Forty-nine patients with histologically proved brain tumors (eight high- and 12 low-grade astrocytomas, eight metastases, eight nonastrocytic gliomas, seven meningiomas, three dysembryoplastic neuroepithelial tumors (DNETs), and three tuberculomas) were prospectively evaluated with contrast material-enhanced MR imaging, single-voxel proton MR spectroscopy (TE = 135 ms), and diffusion-weighted imaging (b = 0, 500, and 1000 s/mm(2)) before surgery.

RESULTS

MR spectroscopy could differentiate benign from malignant tumors but was not useful in grading malignant tumors. In the differentiation of malignant from benign tumors, N-acetylaspartate (NAA)/choline (Cho), NAA/Cho + creatine (Cr), lactate/Cr, and alanin/Cr ratios (P <.001) were statistically more significant than NAA/Cr and lactate/lipid ratios (P <.05). Increase in lipid/Cr and alanin/Cr ratios could distinguish metastasis and meningiomas from other tumors, respectively (P <.001). DNETs could be diagnosed by their normal spectra and high ADC values (116.25 +/- 6.93 x 10(-3) mm(2)/s). Increase in lactate/Cr ratio correlated with degree of malignancy (r = -0.71). ADCs were effective for grading malignant tumors (P <.001) but not for distinguishing different tumor types with the same grade. High-grade malignant tumors (87.16 +/- 10.41 x 10(-3) mm(2)/s) had significantly lower ADC values than did low-grade malignant (115.33 +/- 11.67 x 10(-3) mm(2)/s) and benign (107.69 +/- 8.05 x 10(-3) mm(2)/s) tumors. Peritumoral ADCs were significantly higher in low-grade than in high-grade astrocytomas (P <.05).

CONCLUSION

Combination of calculated ADC values from tumoral core and specific relative metabolite ratios acquired by MR spectroscopy added more information to MR imaging in the differentiation and grading of brain tumors and were more useful together than each alone.

Solitary tuberculoma of the cerebellopontine angle: a rare presentation

Central nervous system tuberculoma presenting as a solitary mass in an extrinsic location is rare. Due to the increase in incidence of tuberculosis in the western world, there is a corresponding increase in CNS tuberculosis. Cerebellopontine angle tumours are most commonly acoustic schwannomas or meningiomas. Radiosurgery as a primary modality of treatment for many CNS masses without prior pathological diagnosis is increasing in popularity. This report shows that a mass in the CP angle can closely mimic a tumour radiologically and inappropriate radiation treatment was avoided after surgery. Histopathological examination proved it to be a tuberculoma. Awareness of this rare presentation of a solitary tuberculoma in the CP angle is emphasised.

[Symptomatic intracranial tuberculoma revealed when the patient receiving therapy for miliary tuberculosis: a case report]

We describe a 20 year old man with miliary tuberculosis of the lung, who was noted to have multiple intracranial tuberculomas on magnetic resonance imaging but not noncontrast head computed tomographic scan receiving antituberculous chemotherapy.

Intraventricular tuberculoma

A 38-year-old female presented with headaches, fever, and malaise. Computed tomography showed an intraventricular peripheral ring-enhanced lesion with central necrosis. The lesion was totally excised. Histological examination revealed a tuberculoma. The patient was treated with antituberculous chemotherapy. The patient was asymptomatic at 9 months. Ventricular involvement in neurotuberculosis is rare, but should be considered in the presence of other indicators of tuberculous infection.

Conventional and diffusion-weighted MR imaging of intracranial tuberculomas. A case report

Intracranial tuberculoma is a rare form of central nervous system tuberculosis. We here report on conventional and diffusion-weighted cranial MR images of a non-immunocompromised patient with multiple intracranial tuberculomas, tuberculous lymphadenitis and pulmonary tuberculosis. Conventional MR imaging revealed multiple ring-enhancing mass lesions. At follow-up MR, appearances of both edema and number and size of nodules were decreased. Diffusion-weighted MR was normal and normal ADC values were found in this case of tuberculomas.

Proton MR spectroscopy and diffusion-weighted MR imaging for the diagnosis of intracranial tuberculomas. Report of two cases

With the current prevalence of tuberculosis, the incidence of intracranial tuberculoma may be on the rise in industrialized nations. However, clinical findings suggestive of systemic tuberculosis are frequently subtle or absent in patients with intracranial tuberculoma, and no specific neuroradiologic characteristics of tuberculoma have been defined as yet. We report two cases of ring-enhanced intracranial tuberculoma in which magnetic resonance (MR) proton spectroscopy and diffusion-weighted (DW) imaging were useful in the differential diagnosis between tuberculoma and other ring-enhanced mass lesions. Pulmonary tuberculosis had been diagnosed in one patient, but radiologic lung study and tuberculin skin test were negative in the other. DW imaging showed bright signal intensity in the core of all lesions in both patients. Malignant gliomas and metastatic brain tumors do not have this characteristic. Proton MR spectroscopy of lesion cores showed lipid peaks and a choline peak in one, and a lipid/lactate mixture pattern in the other, which differed distinctively from those of the pyogenic brain abscess. in each case, one lesion was surgically removed. Antituberculosis drugs were started before surgery for one patient and after surgery for the other. In both, the remaining lesions were reduced significantly in size. We discuss the diagnostic potential of these MR techniques and management options of intracranial tuberculoma.

Solitary pontine tuberculoma

A 66-year-old man, with a history of pulmonary tuberculosis 40 years before admission, complained of headache and dysarthria that lasted for 2 weeks and was followed by diplopia. MRI revealed an isolated nodular lesion in the pons with a marked enhancement mimicking brain tumor and other diseases. Antituberculous drugs were started under the presumptive diagnosis of tuberculoma. The lesion was completely resolved after 9 months of treatment and thus, the final diagnosis was confirmed. An empiric administration of antituberculous drug may be an important and non-invasive diagnostic tool as well as a treatment in such cases.

Comparative evaluation of magnetization transfer MR imaging and in-vivo proton MR spectroscopy in brain tuberculomas

We have compared and analyzed the value of in vivo proton MR spectroscopy (PMRS) and T1 weighted magnetization transfer (MT) MR imaging in tissue characterization of brain tuberculomas. We studied 33 cases of proven intracranial tuberculomas with in vivo PMRS and T1 weighted MT MR imaging. MT ratios from the rim and core of the tuberculomas were calculated and compared with metabolites seen on PMRS. Final diagnosis of tuberculoma was based on histopathology (n = 26) and/or associated tuberculous meningitis (n = 7) in all the cases. Out of the 33 patients who underwent both PMRS and T1 weighted MT MR imaging, spectroscopy showed only lipids at 0.9 ppm, 1.3 ppm, 2.0 ppm, and 2.80 ppm in 26 cases while lipids at 0.9 ppm, 1.3 ppm, 2.0 ppm and 2.80 ppm along with choline at 3.22 ppm was seen in remaining 7 patients. MT ratios from the core or solid necrosis varied from 21-29% while from the rim or cellular region varied from 16-24%. MT ratios from all the 33 lesions were consistent with tuberculomas while PMRS showed choline along with lipids in 7 predominantly cellular lesions simulating a neoplasm. We conclude that T1 weighted MT MR imaging appears to be more consistent in the tissue characterization of brain tuberculomas.

Tuberculoma of the cavernous sinus

A case of tuberculoma of the cavernous sinus is described and 4 other previously reported cases are reviewed. The condition is very rare, and predominantly affects Asians. Periorbital pain, ptosis and ophthalmoplegia are the most common presenting features. Clinical and radiological findings are not sufficiently sensitive to differentiate it from other diseases affecting the cavernous sinus. Treatment is primarily medical, with antituberculous drugs, and the outcome is good. Surgery has a limited role in the management of this condition, mainly for establishing the diagnosis.

[Case report: evaluation of two cases of tuberculoma incident to tuberculosis meningitis]

Intracranial tuberculoma is one of the most serious complications of tuberculous meningitis. In this report, two patients who develop intracranial tuberculoma as a complication of tuberculous meningitis have been presented. The first patient was a 35 years old male patient who were still been in therapy for cavitary tuberculosis. The other one was 42 years old male patient and have had treated for subdural empyema two years ago. There was no positivity in both of the cerebrospinal fluid (CSF) specimens of the patients by Gram and Erlich Ziehl Neelsen stained preparations, while the CSF sample of the first case yielded Mycobacterium tuberculosis in culture. The tuberculoma diagnosis of these patients managed by the help of computerized tomography (CT) and nuclear magnetic resonance imaging (NMR) methods. As a result, it was thought that CT and NMR techniques have a great role in the diagnosis and management of complications in tuberculous meningitis patients.

Intrasellar tuberculoma presenting as pituitary apoplexy

The combination of apoplectic symptoms and a sellar mass most often points to a diagnosis of a pituitary adenoma. Sellar tuberculomas are not considered as a cause of 'pituitary apoplexy' and there has been no radiological documentation of haemorrhage associated with them. We report a 27 years old man who presented with 3 previous episodes of pituitary apoplexy. CT scan showed evidence of a sellar mass with haemorrhage. Transsphenoidal biopsy of the intrasellar mass was reported as 'tuberculoma'. The patient had marked reduction in the size of the lesion following antituberculous therapy with no recurrence of symptoms. Intrasellar tuberculomas must be considered as one of the differential diagnosis when patients present with a pituitary apoplexy.

[Multiple cerebral tuberculomas presenting with paradoxical expansion: a case report]

A 24-year-old male presented with headache. He had been treated with antituberculous drugs for 19 months. MRI revealed 4 intracranial Gd-DTPA enhanced lesions surrounded by massive edema in the right frontal, both occipital and left basal ganglionic regions. Digital subtraction angiography showed no tumor stain. Two procedures for tumor resection were performed for the right frontal and left occipital regions, the latter of which definitively diagnosed by the polymerase chain reaction method. The tumors were well demarcated, showed a rough surface, and were elastically hard. The two residual lesions responded differently to chemotherapy. The lesion in the right occipital region decreased in size, while the other in the left basal ganglionic region continued to grow gradually 26 months after the antituberculous chemotherapy was started. According to previous reports, treatment should be continued for as long as 12-30 months in cases showing paradoxical expansion. In this case, the left basal ganglionic lesion began to decrease in size after 28 months of administration of anti-tuberculous drugs. We report successful treatment of a case of multiple tuberculomas presenting with paradoxical expansion managed by a combination of surgery and continuous chemotherapy.

Intracranial and spinal tuberculosis requiring neurosurgical intervention. The Wellington Hospital experience 1998-2001

AIMS

To describe the Wellington Neurosurgical Unit's recent experience of managing tuberculosis between January 1998 and January 2001.

METHODS

Patients with microbiologically confirmed tuberculosis of the central nervous system and whose management included surgery are described. Personal recall and review of the hospital records were used to extract relevant data.

RESULTS

Five patients were identified. As well as involvement of the brain parenchyma, meninges, spinal cord or spinal column, all had evidence of tuberculosis elsewhere. All but one patient deteriorated neurologically after being started on antituberculous chemotherapy.

CONCLUSIONS

The number of patients presenting with neurotuberculosis appears to have increased recently in the Wellington region. The high proportion of paradoxical progression in our series is unusual. Neurosurgical intervention may be required for diagnosis, to treat hydrocephalus, or to relieve mass effect. Management is prolonged and often complex, and close co-operation is required between the neurosurgical team and a physician experienced in the management of tuberculosis.

Differentiation of tuberculous from pyogenic brain abscesses with in vivo proton MR spectroscopy and magnetization transfer MR imaging

BACKGROUND AND PURPOSE

MR imaging features are nonspecific with respect to the causative organism for patients with brain abscesses. On the basis of the hypothesis that the biochemical environment depends on the infecting organism and might be different in tuberculous compared with pyogenic brain abscesses, this study attempted to determine whether pyogenic brain abscesses can be differentiated from tuberculous brain abscesses by use of magnetization transfer (MT) MR imaging and in vivo proton MR spectroscopy.

METHODS

Twenty-seven patients with a total of 33 pyogenic brain abscesses and three patients with a total of 12 tuberculous abscesses were evaluated with in vivo MR spectroscopy and MT MR imaging. The diagnosis in all cases was based on the culture of the causative organisms and histopathology whenever done as a part of clinical management.

RESULTS

All 27 patients with pyogenic brain abscesses had lipid and lactate levels of 1.3 ppm and amino acid levels of 0.9 ppm with or without the presence of succinate, acetate, alanine, and glycine, while the three patients with tuberculous abscesses showed only such lipid and lactate levels. The MT ratio from the wall of the pyogenic abscesses was significantly higher (P <.001) than that from the tuberculous abscess wall.

CONCLUSION

It might be possible to differentiate tuberculous abscesses from pyogenic abscesses by using MT MR imaging and in vivo MR spectroscopy, which could be of value in influencing the management of such cases.

Magnetization transfer MR imaging correlation with histopathology in intracranial tuberculomas

OBJECTIVE

The purpose of this study was to correlate the differences in the magnetization transfer (MT) ratios of different components of the tuberculoma with histopathology and to see whether MT or conventional MR imaging correlates better with histopathology.

METHODS

MT T1 and conventional spin echo MR imaging was performed in six patients with intracranial tuberculomas. The tuberculomas were excised as a single mass and ex vivo MR imaging was performed using the same protocol. The gross histopathology was compared with in vivo imaging with respect to the MR signal intensity (MT ratio) in all six specimens.

RESULTS

The size of the tuberculomas was larger on MT T1-weighted images compared to T2-weighted images and matched the gross measurements of each specimen. The MT hyperintense rim matched the cellular component of the tuberculoma that was masked on T2-weighted images because of the associated perifocal oedema. The cellular component had a lower MT ratio compared to the necrotic components.

CONCLUSION

The outer hyperintense rim and hyperintense strands are due to the cellular infiltrate, noncaseating granulomas, and gliosis while the hypointense core represents solid caseation. The cellular outer rim shows lower MT ratio compared to the core of the tuberculoma. Histological correlation of the cellular and necrotic components of tuberculomas is best shown with MT T1 imaging.

[Multiple intracranial tuberculomas in infancy]

INTRODUCTION

Tuberculous involvement of the CNS is most frequent in children aged between 6 months and 6 years, although it may occur at any age. It may present as meningoencephalitis, basal arachnoiditis or intracranial tuberculomas. Whilst meningitis is typical of infancy, tuberculomas and arachnoiditis are commoner in adults. It has been estimated that tuberculomas make up 3% of the cases of neurotuberculosis. The increasing use of CAT and MR has been a great help for diagnosis of this serious complication of tuberculosis.

CLINICAL CASE

A 5 month old patient presented with tuberculous meningitis which had been treated with streptomycin, isoniazid, pyrazinamide and rifampicin at the usual dosage. One month later, after good initial progress, triventricular hydrocephaly was diagnosed and a ventriculoperitoneal shunt inserted. Three months after this, there was an episode of intracranial hypertension. Cranial CAT showed considerable zones of hypodense parenchyma without ventricle dilatation. On MR there were multiple, disseminated, rounded areas which were hyperintense on T2 and compatible with intracranial tuberculomas. After fresh insertion of a ventricular shunt, the patient progressed but still had a residual right hemiparesia and retarded development.

CONCLUSIONS

Although intracranial tuberculomas usually occur in adults, they may be seen in children following meningoencephalitis. Occasionally, following a good initial response to tuberculostatic drugs, tuberculomas appear, although not present before, as happened in our patient. This usually occurs within the first three months, and although the mechanism is unknown, it is believed to be due to the accumulation of lymphocytes and macrophages at preexisting microscopic foci when treatment is started.

Focal limb dystonia in a patient with a cerebellar mass

BACKGROUND

Focal dystonia of acute onset is indicative of a structural lesion in the nervous system. Cerebellar lesions have rarely been associated with dystonia.

CASE DESCRIPTION

A 42-year-old woman was admitted to the neurology ward because of fever, confusion, and gait unsteadiness. She was diagnosed as having tuberculous meningitis, and, after a few days of antituberculous treatment, she developed prominent dystonia of the left upper limb. Cranial nuclear magnetic resonance imaging showed an isolated lesion compatible with a tuberculoma in the left cerebellar hemisphere. Both the limb dystonia and the tuberculoma resolved with maintained antituberculous treatment.

CONCLUSIONS

In the patient described, the presence of upper-limb dystonia ipsilateral to a focal cerebellar lesion and the resolution of the dystonia and the mass lesion following treatment suggest that the cerebellum or its connections to the thalamus and/or basal ganglia could be involved in the pathophysiology of the dystonia.