Value of 123I-IMT SPECT for diagnosis of recurrent non-astrocytic intracranial tumours.

The value of single-photon emission tomography (SPECT) using iodine-123-alpha-methyl-tyrosine (IMT) for the diagnosis of recurrent or residual gliomas is well established. In the current study we investigated whether IMT-SPECT could also be useful in the follow-up of brain metastases and other intracranial tumours of non-astrocytic origin. The study included 22 patients with suspected recurrent intracranial tumours of non-astrocytic origin (12 brain metastases, one supratentorial primitive neuroendocrine tumour (PNET), one rhabdoid tumour, two clivus chordomas, three ependymomas, two pituitary tumours, one anaplastic meningioma) who had previously been treated by surgery and/or radio/chemotherapy. SPECT results were correlated with clinical and MRI follow-up data. The study was true positive in 13 patients, true negative in five, false positive in one and false negative in three patients. Notably, all false negative findings were <13 mm. The resulting sensitivity of the IMT-SPECT was 81%. We concluded that the IMT-SPECT is a promising complementary imaging tool for the detection of recurrences of non-astrocytic intracranial tumours and their distinguishing from treatment-induced changes. The limitation of the IMT-SPECT is its low sensitivity for the detection of small lesions.

Magnetic resonance imaging versus computed tomography scan: accurate diagnosis of soft tissue lesions.

Due to their cost effectiveness and accessibility, computed tomography (CT) scans are being utilized when magnetic resonance imaging (MRI) appears to be the diagnostic technique of choice. Because of their availability, CT scans are still used for diagnosis of disc herniations. MRI may, however, be superior in its specificity. In taking into account the subjective complaint and orthopedic and neurological findings, a disk herniation can often be diagnosed without a CT scan or MRI. However, should the patient fail to respond to conservative care or show unusual symptoms, an MRI is indicated. This article discusses a case where MRI would be the imaging procedure of choice.

Subarachnoid hemorrhage from brain tumors in childhood.

Six children are reported in whom subarachnoid hemorrhage was an initial symptom of brain tumor. In our neurosurgical clinics, this represented 3.6% of pediatric brain tumors and showed a frequency equal to aneurysmal rupture among nontraumatic subarachnoid hemorrhage of children. In pediatric patients, hemorrhages from brain tumors occur predominantly in the posterior fossa. The medulloblastoma, which had been believed to bleed rarely, is now realized to be a common source of tumor hemorrhages in such cases. The introduction of CT scan facilitates early recognition of hemorrhagic stroke from brain tumors and prompt management for acute intracranial hypertension and brainstem dysfunction. Although the patients achieve favorable recovery from their initial catastrophic condition, the ultimate prognosis, in the majority of cases, is still rather poor because such hemorrhages usually develop from a malignant tumor. The present and other recent reports indicate that the incidence of hemorrhagic stroke from brain tumors in pediatric patients is much higher than has been thought and is an important cause of subarachnoid hemorrhage in this age group.

Median and tibial somatosensory evoked potentials. Changes in short- and long-latency components in patients with lesions of the thalamus and thalamo-cortical radiations.

Alterations in short- and long-latency components of median and tibial somatosensory evoked potentials (SEPs) were studied in patients with lesions in the thalamus and thalamo-cortical radiations. When the lesions were located primarily in the ventro-posterior thalamus, the SEP changes consisted of the following combination: absence of response; decrease in response amplitude; delay in peak latency; and attenuation of median N20-P25 and tibial P40. The laterally situated ventro-posterior lesions tended to preferentially affect tibial SEPs whereas the medially situated lesions tended to preferentially affect median SEPs. The lateral thalamic lesions affected primarily the long-latency SEP components, whereas the medial thalamic lesions affected primarily the mid-latency or the mid- and long-latency SEP components. Corona radiata infarcts produced SEP changes similar to those with the ventro-posterior thalamic lesions except that absence of evoked responses was not observed. Subcortical infarcts tended to affect the mid- and long-latency SEP components with relative preservation of the short-latency components. The present data indicate that only the lesions involving the primary thalamic relay area affected all SEP components, particularly the short-latency components, and that the lesions in other thalamic areas can also influence the SEPs, particularly the mid- and long-latency components. The present study further demonstrates that a combined use of median and tibial SEPs is useful in delineating the topographic organization of the somatosensory system in the thalamus.

Sustained tumour opacification in infants during cerebral angiography.

Total body opacification in infants following the intravenous injection of a large dose of water soluble contrast medium has long been recognised, but no example of increased radiodensity of abdominal or intracranial tumours has been reported using this technique. This paper reports the sustained opacification of intracranial tumours in three infants during cerebral angiography. Two of the tumours were papillomas of the choroid plexus of the lateral ventricle and the third a medulloblastoma of the fourth ventricle. Three possible explanations of this phenomenon are briefly considered: 1. That the amount of contrast medium was sufficient to cause total body opacification and the visibility of the tumours was due to a combination of their vascularity and the iodine concentration in the circulation blood. 2. That the observed phenomenon is peculiar to these tumours. 3. That the sustained opacity of these these tumours is due to the same cause or causes as the density enhancement of some intracranial tumours demonstrated by computerised tomography after intravenous injection of contrast medium.