Cranial computed tomography in leukaemia

Childhood central nervous system leukemia: historical perspectives, current therapy, and acute neurological sequelae

INTRODUCTION

During the past three decades, improvements in the treatment of childhood leukemia have resulted in high cure rates, particularly for acute lymphoblastic leukemia (ALL). Unfortunately, successful therapy has come with a price, as significant morbidity can result from neurological affects which harm the brain and spinal cord. The expectation and hope is that chemotherapy, as a primary means of CNS therapy, will result in acceptable disease control with less CNS morbidity than has been observed with combinations of chemotherapy and radiotherapy over the past several decades.

METHODS AND RESULTS

In this review we discuss the poignant, historical aspects of CNS leukemia therapy, outline current methods of systemic and CNS leukemia therapy, and present imaging findings we have encountered in childhood leukemia patients with a variety of acute neurological conditions. A major objective of our research is to understand the neuroimaging correlates of acute and chronic effects of cancer and therapy. Specific features related to CNS leukemia and associated short-term toxicities, both disease- and therapy-related, are emphasized in this review with the specific neuroimaging findings. Specific CNS findings are similarly important when treating acute myelogenous leukemia (AML), and details of leukemic involvement and toxicities are also presented in this entity.

CONCLUSION

Despite contemporary treatment approaches which favor the use of chemotherapy (including intrathecal therapy) over radiotherapy in the treatment of CNS leukemia, children still occasionally experience morbid neurotoxicity. Standard neuroimaging is sufficient to identify a variety of neurotoxic sequelae in children, and often suggest specific etiologies. Specific neuroimaging findings frequently indicate a need to alter antileukemia therapy. It is important to appreciate that intrathecal and high doses of systemic chemotherapy are not innocuous and are associated with acute, specific, recognizable, and often serious neurological consequences.

Case report: CT and MRI demonstration of hypothalamic and infundibular relapse in childhood acute lymphoblastic leukaemia

The central nervous system is affected in up to 10% of patients with acute lymphoblastic leukaemia, usually in the form of leptomeningeal infiltration. Parenchymal spread is rare. We report a case in which CT and MRI demonstrated hypothalamic and infundibular relapse.

Reversible changes on computed tomography scans of the brain during induction therapy for acute lymphoblastic leukemia in children

Children with acute lymphoblastic leukemia (ALL) have been shown to develop changes on computed tomography (CT) scans of the brain. These changes are seen both during and after therapy. Some of the results have been contradictory. Nine children with ALL were examined by CT of the brain during induction therapy. All children showed normal CT scans on the day of diagnosis. One month later all had dilatation of the ventricles and widened sulci. During the next 9 months the CT scans gradually were normalized. We conclude that such changes in CT scans of the brain are transitory and are caused by the high dose of prednisolone administered during induction therapy.

Subacute brain atrophy after radiation therapy for malignant brain tumor

Brain atrophy with mental and neurologic deterioration developing a few months after radiation therapy in patients without residual or recurrent brain tumors has been recognized. Two illustrative case reports of this pathologic entity are presented. Six autopsy cases with this entity including the two cases were reviewed neurologically, radiographically, and histopathologically. All patients presented progressive disturbances of mental status and consciousness, akinesia, and tremor-like involuntary movement. Computerized tomography (CT) demonstrated marked enlargement of the ventricles, moderate widening of the cortical sulci, and a moderately attenuated CT number for the white matter in all six patients. Four of the six patients had CSF drainage (ventriculoperitoneal shunt or continuous lumbar drainage), however, none of them improved. Histologic examination demonstrated swelling and loss of the myelin sheath in the white matter in all patients, and reactive astrocytosis in three of the six patients. Neither prominent neuronal loss in the cerebral cortex or basal ganglia, nor axonal loss in the white matter was generally identified. The blood vessels of the cerebral cortex and white matter were normal. Ependymal layer and the surrounding brain tissue were normal in all patients. These findings suggested that this pathologic condition results from demyelination secondary to direct neurotoxic effect of irradiation. The authors' previous report was reviewed and the differential diagnoses, the risk factors for this pathologic entity, and the indication for radiation therapy in aged patients with a malignant brain tumor are discussed.

Computed tomography of the brain following prophylactic treatment with irradiation therapy and intraspinal methotrexate in children with acute lymphoblastic leukemia

In 28 children with acute lymphoblastic leukemia (ALL) computed tomography (CT) was performed in order to demonstrate possible cerebral changes following treatment with prophylactic irradiation and intraspinal methotrexate (MTX). The time of CT-scan examination varied from 1 year and 1 month to 10 years and 1 month after diagnosis of ALL. The age of the children ranged from 3 years and 11 months to 14 years and 5 months. Six children had normal CT scans, 12 children had slight atrophy-like changes, and nine had severe cerebral atrophy. Two patients in the latter group presented an enlarged ventricular system as well. In one patient intracerebral calcification was the only pathologic finding. The severe changes were seen in children of all age groups, but predominantly in children with a short duration of their disease, severe symptoms, and frequent marrow relapse. Changes induced by steroid therapy may be reversible. No satisfactory explanation of the demonstrated cerebral pathologic findings can be given, except that they are the consequences of the combination of total therapy and severity of disease in the individual patient. Measurement of attenuation coefficients in grey and white matter shows increasing values with age during childhood. A combination of decreasing attenuation coefficients, especially in the white matter, and the finding of severe atrophy seems to be a bad prognostic sign.

The development of cerebral CT changes during treatment of acute lymphocytic leukemia in childhood

Twenty-three children with acute lymphocytic leukemia (ALL) were examined with cranial CT at least twice with a minimal interval of 10 months. The first CT was performed at the time of diagnosis in 11 children and during therapy in 12; all but two were normal on the first CT examination. These two had slight enlargement of the ventricular system and subarachnoid space at the time of diagnosis. These findings were unchanged on the second CT examinations. Seven patients, all in remission from leukemia of the central nervous system manifested abnormal findings on later CTs. Low density areas in the periventricular white matter were seen in the brains of three, with increasing subcortical calcification in one of these cases. Five children had slight enlargement of the ventricular system and subarachnoid space, especially of the basal and Sylvian cisterns. Later CT examinations in five, plus brain autopsy in two cases, revealed unchanged or progressive conditions. The CT findings have been related to the treatment and some characteristics of the disease. The frequency of CT abnormalities was higher in patients who had received therapeutic irradiation and intraventricular methotrexate treatment. The possible reasons for the CT abnormalities are discussed.

Computed tomography brain scans in long term survivors of childhood acute lymphoblastic leukemia

There have been varying frequencies cited for the occurrence of abnormal brain CT scans in leukemic patients and conflicting evidence about the significance of these abnormalities and their relationship to sanctuary therapy. Our study of CT brain scans in 26 long survivors of acute lymphoblastic leukemia showed an overall prevalence of 35% abnormal scans. There was no statistically significant difference between the number of abnormal scans in patients given radiotherapy as part of their CNS prophylaxis and those receiving only intrathecal methotrexate. Because the children in each treatment group were evenly matched with respect to other treatment variables possibly relevant to the causation of abnormal brain scans, a strong case is made for more rigorous design of such studies, preferably in a prospective fashion, looking simultaneously at other parameters of brain structure and function.

CT studies before and after CNS treatment for acute lymphoblastic leukemia and malignant non-hodgkin's lymphoma in childhood

CT was performed on 72 children with acute lymphoblastic leukemia or non-Hodgkin's lymphoma. Thirty-two of these patients were investigated prior to CNS radiation and intrathecal methotrexate therapy. Ten of these patients (31%) were known to have hydrocephalic dilatation of the CSF spaces. Clinical data and subsequent observations with analysis of the CT findings show that no difference in the attenuation values of brain tissue occurs in the absence of a CNS relapse. The percentage of abnormal findings before and after therapy remains constant. The adverse late effect described in the CT literature seem principally to be damage diagnosed too late. It is questionable if the CT demonstration of dilated CSF spaces before treatment has a prognostic significance.

Basal ganglia calcification on CT scanning in children with acute lymphocytic leukemia

Calcification occurring in the basal ganglia in children with acute lymphocyte leukemia following therapy is uncommon and to the best of our knowledge has not been reported prior to therapy. Eleven cases of bilateral symmetrical calcification in the basal ganglia were noted in 2350 CT scans, two being in children with acute lymphocytic leukemia. In one of the two cases, calcification was present prior to therapy.