F. Roncallo

Functional perfusion and blood-brain barrier permeability images in the diagnosis of cerebral tumors by angio CT

We performed rapid sequential CT scanning following iv injection of a bolus of contrast medium and generated three functional images relating to intravascular circulation time (rABCT), vascular volume (Vv) density and blood-brain barrier (BBB) unidirectional constant uptake rate (Ki), respectively. This was accomplished by calculating the first mathematical moment of the monitored time-density curves about the injection time and from the multiple time graph analysis described by Patlack and co-workers. A satisfactory resolution was achieved, allowing separate appreciation of changes in rABCT both in large vessels and in tissue small vessels. Combined evaluation of rABCT and Vv images allowed us to differentiate between tumors.

Assessment of regional cerebral blood flow images with non-diffusible contrast media and angio-CT. Comparison with Xe-CT

We derived rCBF (ND-rCBF) images using non-diffusible contrast agent time-density curves obtained by monitoring the first pass with an angio-CT sequence. An appropriate elaboration of the sequence of the images led to the generation of vascular volume (Vv) and regional Arm-Brain circulation time images (rABCT). ND-rCBF was obtained by dividing the Vv image by the rABCT image after having rendered them suitable for such an operation. Regional cerebral vascular volume (rCBF) was assessed by standardizing Vv values with blood contrast concentration and intracranial circulation time (rICT) by subtracting from the rABCT image the inflow mean time, assessed as the lowest rABCT value of the slice. The ND-rCBF images were qualitatively fairly well comparable with synchronous rCBF (D-rCBF) images obtained with the Xe-CT technique. However quantitation of the values by ROI use gave different results, the ND-rCBF image showing considerably higher values. Using indicator images to analyse the rCBF values at different levels of rCBV and rICT, it was shown that there was a significant relation between the two ND-rCBF and D-rCBF values in the 70-80% pixels with higher rABCT and lower rCBF values.

Cerebral Venous Sinus Thrombosis: Prognostic and Therapeutic Significance of an Early Radiologic Diagnosis

We describe the CT and MRI patterns of cerebral venous sinus thrombosis (CVST) on the basis of the venous angioarchitecture and the underlying pathophysiological mechanism. We also investigated if any radiologic data exist to establish which patients can be followed conservatively and which warrant endovascular treatment. The clinical, CT-CTA and MRI-MRA findings of 11 patients (2 men; 9 women; 24 to 69 years-old) with CVST were reviewed. The morphological patterns of CVST were divided into two major groups: Vascular signs: spontaneous sinusal hyperdensity (9); spontaneous all-sequences hyperintensity (4); venous engorgement (9); empty delta sign (4); lack of sinusal contrast-enhancement (3); delayed sinusal transit-time (11); lack of flow-related signal (3). Parenchymal signs: mass effect and cortical sulcal effacement (8), white matter edema (7), venous ischemia (6), haemorrhagic infarct (3), breakdown of the blood-brain barrier (4), hydrocephalus (2). The clinical and radiologic pictures are related to cerebral venous angioarchitecture and underlying pathophysiologic mechanism of venous thrombosis. Reversibility of clinical symptoms and parenchymal lesions is far more frequent, because vessel damage slowly and progressively develops, whereas damage to brain tissue occurs later. Consequently, a prompt CT-MRI diagnosis may allow a good prognosis. Treatment using selective sinusal instillation of urokinase is considered only when the patient clinically and radiologically does not improve within the first two weeks after heparinization.

Assessment of the CO2 response by means of non diffusible contrast media and Angio-CT in patients with cluster headache

We analyzed the possibility of assessing functional vasomotor changes by means of Arm-Brain Circulation Time (rABCT) and Vascular volume images (Vv) obtained with Angio-CT, in basal condition and following CO2 inhalation, in a sample of 48 patients with cluster headache. CO2 inhalation resulted in the appearance of local changes, which were detected in 28 regions. Analysis by indicator images of Vv-dependent rABCT distribution showed two main patterns: abnormal rABCT mostly evident at the smallest Vv pixels and abnormal rABCT dependent on abnormal Vv distribution. The former pattern was linked to abnormality at the circle of Willis; the latter to abnormal local vasomotor responses. Patients with cluster headache showed both patterns, which prompted us to conclude for the presence of low-degree stenosis in carotid arteries and vasomotor instability in peripheral brain vessels.

Trigeminal Neuropathy: A Pictorial Essay

Trigeminal (cranial nerve V) neuralgia and/or palsy is quite common. Damage to this nerve produces characteristic clinical manifestations, of which unilateral facial pain and/or atrophy of the masticator musculature is the most important. When these clinical features are recognized, the radiologist, armed with knowledge of the normal anatomy of the area, can focus on each segment of the nerve in search of a cause. The trigeminal nerve and its branches is divided into four segments: the intraaxial, cisternal, gasserian, and peripheral segments. Because each segment is usually affected by different disorders, localizing a lesion to a particular segment allows the radiologist to narrow the differential diagnosis. In this way, the most efficient imaging strategy for evaluation of the symptoms can be developed. Both computed tomography and magnetic resonance imaging are useful in assessing dysfunction of the trigeminal nerve; the choice depends on the status of the patient, the presumed site of the lesion on the basis of clinical findings, and the preference of the radiologist.

Protocollo diagnostico non invasivo nelle stenosi carotidee

Digital Subtraction Angiography (DSA) is now considered the elective diagnostic tool in the evaluation of carotid artery steno-occlusive pathology, although the use of intra-artery catheters implies some iatrogenic risk. Aim of the study is to evaluate the possible utilization of a flow-chart based on non-invasive diagnostic tools, such as Ultrasound (US) and Angio-CT in the pathology of neck vessels. We retrospectively evaluated 35 pts with previous Transient Ischaemic Attacks (TIAs) in the carotid artery territory, aged between 38 and 67 years; 21 males, 14 females. The NASCET classification was used to quantify the entity of each carotid stenosis. All patients underwent neck US and Angio-CT; in 15 of them Angio-MRI and DSA were also performed. Angio-CT protocol implies volumetric acquisition from the C6 to the suprasellar region, 3 mm thick slices, 1.5 pitch, 100 ml TV c.m., 3 ml/20 s acquisition time, 1 mm axial image reconstruction, elaboration techniques: SSD, MIP. US and Angio-CT images were comparated with Angio-MRI and DSA findings; according to the present study, axial, SSD, MIP Angio-CT images have the same accuracy as DSA in the evaluation of vessel course and stenosis degree; in the evaluation of the vessel course only they are comparable to Angio-MRI; in the quantification of the stenosis their reliability is the same as US. Angio-CT is more sensitive than DSA and MRI in the evaluation of parietal abnormalities. The complementary use of US and Angio-CT techniques gives functional and anatomical information about extra-and intracranial carotid course, making invesigation possible also in uncooperative patients with minimal invasivity.

Functional circulation images by angio-CT in the assessment of small deep cerebral infarctions

We analyzed circulation time (rABCT) and vascular volume density images obtained by angio-computerized tomography (angio-CT) in 63 patients with small deep cerebral infarctions. Abnormalities in the rABCT image were found in 88% of the patients and in the vascular volume image in 48%. Two groups with different clinical pictures were picked out by rABCT changes: one with major-vessel involvement, the other with small-vessel involvement. The perfusional changes found were mainly due to altered vascular canalization rather than to altered vasomotility. The hemodynamic theory could explain the spatial relations between perfusion changes and CT hypodense areas without needing assumptions linking blood flow and metabolism.

Assessment of 99mTc-HM-PAO parameters with SPECT for improved evaluation of blood flow in cerebral lesions

A method for investigating the linearity between blood flow and distribution of 99mTc-HM-PAO uptake in patients undergoing single photon emission computed tomography (SPECT) is presented. This method, based on particular elaboration techniques of sequential multiple acquisitions, provides a local index: cumulative transit time (CTT) related to all factors, other than blood flow, affecting 99mTc-HM-PAO uptake. Because a correct qualitative blood flow estimation is based on the uniformity of the above factors, the occurrence of a change of this index indicates a nonlinear relation between blood flow and 99mTc-HM-PAO uptake distributions. It was shown that although linearity between blood flow and 99mTc-HM-PAO uptake may be questionable, a qualitative assessment of blood flow was correct in 100% of ischemic patients. In nonischemic patients this percentage fell to 60%.

Meningioma of the Lateral Ventricle in a Young Adult MR Findings and Differential Diagnosis

Intraventricular neoplasms are uncommon CNS masses, representing only 10% of all tumours. Previous studies of intraventricular neoplasms have shown consistent trends in tumour location and in the age of patient presentation. Within the lateral ventricle, specific regions can be identified as sites of predilection for each particular tumour. It was found that these tumours tend to occur in natural age-related groupings. Meningiomas of the lateral ventricles of the brain are rare tumours. The incidence of this tumour type is very low, since they account for only 0.2% of all intracranial neoplasms and 0.5–5% of all intracranial meningiomas. We present a case of an intraventricular meningioma arising from the trigone in a young adult and discuss the available literature on intraventricular meningiomas and its differential diagnosis.

Acute Disseminated Encephalomyelitis: Clinical, CSF, and MRI Findings and the Distinction from Multiple Sclerosis

Acute disseminated encephalomyelitis (ADEM) is an inflammatory demyelinating disorder of the central nervous system usually developing in close temporal relationship to an infective illness or vaccination. This paper presents clinical, cerebrospinal fluid and MRI findings in ADEM and discusses the role of the MRI in the distinction of ADEM and MS. We reviewed the medical records, cerebrospinal fluid (CSF) and MRI studies of six consecutive patients diagnosed as having ADEM during a three-year period. All patients had CSF, including electrophoresis for demonstration of oligoclonal bands, and MRI studies in the acute stage; five patients repeated these examinations in the subacute and chronic stages. Four patients had clinical evidence of a multifocal neurological syndrome. In the two other cases there was clinical evidence only of transverse myelitis. The CSF was abnormal in all cases and showed a mild increase in cell count and protein. IgG synthesis and myelin basic protein were present in three patients. MRI was abnormal in all six patients in the acute stage of the illness. In five cases there were some features of the distribution of the lesions which differed from those usually seen in MS. One showed extensive asymmetric bilateral changes; two had high signal lesions in the basal ganglia and thalamus; two demonstrated a tumour-like mass. One patient died one week after clinical onset and the pathologic findings showed an acute haemorrhagic leukoencephalitis. One patient demonstrated a recurrent MRI pattern of diffuse periventricular white matter lesions, after an abrupt end of corticosteroid treatment. Five patients demonstrated a marked decrease in the size and number of the lesions after steroid treatment; no new lesions were identified. The CNS white matter may be affected by inflammatory demyelinating disorders, including ADEM, that cause clinical diagnostic difficulty with MS. MS and ADEM may be indistinguishable in the acute phase. The clinical course of the disease together with the follow-up MRI will distinguish one entity from the other. Long-term follow-up disclosing newly appearing symptoms and lesions is against the diagnosis of ADEM, because this entity is typically a monophasic disease, unlike MS that usually has a releasing and relapsing course.