A. Bartolini

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.

Functional circulation and blood-brain permeability images by angio CT in the assessment of cerebral ischemia

We performed rapid sequential computerized tomography (CT) scanning following i.v. injection of a bolus of contrast medium, and generated three functional images related, respectively, to intravascular circulation time (rABCT), vascular volume density (Vv) and blood-brain barrier (BBB) unidirectional constant uptake rate (Ki). This was accomplished by calculating the first mathematical moment of the monitored time-density curves about the injection time, and by the multiple time graph analysis described by Patlack and coworkers. A satisfactory resolution was achieved, allowing separate appreciation of changes in rABCT both at large vessels and at tissue small vessels. Combined evaluation of rABCT and Vv images allowed us to draw qualitative conclusions about blood flow and perfusion reserve.

Hemodynamic assessment of vascular malformations by angio CT with generation of functional transit time images.

We performed a CT dynamic study during the first pass of an intravenously injected bolus of a iodinated contrast medium, followed by generation of the regional arm-brain circulation time (rABCT) image, in 11 patients with vascular malformations. All lesions could be detected as changes of rABCT, and the comparison with values of normal arteries and veins allowed the deduction of the hemodynamic conditions of the lesions. Seven cases showed evidence of altered distribution of rABCT in the corresponding brain hemisphere, suggesting a perfusion reserve impairment.

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.

Relationships between perfusion defects and static brain scan positivity in patients with ischaemic completed stroke: considerations about the origin of the increased uptake

The relation between perfusion defects shown by radionuclide angiography and static brain scan positivity was evaluated in patients with ischaemic completed stroke at various intervals from the onset of symptoms. An inverse relation between radionuclide angiography and static scan positivity was found for the period within 15 days of the onset of symptoms. The possible relation between changes in perfusion and static brain scan positivity is discussed.

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.