Radiation doses in cerebral perfusion computed tomography: patient and phantom study.

The purpose of this study was to investigate radiation doses in cerebral perfusion computed tomography (CT) examination. As a part of routine patient monitoring, data were collected on patients in terms of the skin dose and CT dose index (CTDIvol) and dose-length product (DLP) values. For the estimation of the dose to the lens a phantom study was performed. Dose values for skin and lens were below the threshold for deterministic effects. The results were also compared with already published data. For better comparison, the effective dose was also estimated. The values collected on patients were in the ranges 230-680 mGy for CTDI and 2120-2740 mGy cm for DLP, while the skin dose and estimated effective dose were 340-800 mGy and 4.9-6.3 mSv, respectively. These values measured in the phantom study were similar, while the doses estimated to the lens were 53 and 51 mGy for the right and left lens, respectively.

[Fluid attenuated inversion recovery sequences: indications in neuroradiology]. / Indicazioni delle sequenze Fluid Attenuated Inversion Recovery nella neuroradiologia.

The acronym FLAIR refers to fluid attenuation inversion recovery sequences, which are T2-weighted MR pulse sequences with liquor signal saturation by a long TI. They are characterized by long TR and TE and therefore the acquisition time is very long in the conventional mode, while fast imaging (the Turbo mode) reduces acquisition time to less than 2 minutes. Our study was aimed at codifying the use of this type of sequence in neuroradiologic studies. All the exams were performed with an MR unit with a 1-Tesla magnetic field. We carried out 150 neuroradiologic exams with this pulse sequence on patients with cerebral, medullary or orbital conditions. This technique is very useful to study periventricular or cortical lesions in multiple sclerosis and in other multifocal cerebral conditions (e.g., multiple metastases or lacunar infarcts), but we pointed out the following other advantages: better definition of the extent of infiltrative white matter lesions (i.e., gliomatosis cerebri and lymphomas), better differentiation of cystic from necrotic cavities and exact characterization of cortical damage in cerebral ischemic lesions (useful also for the differential diagnosis). Moreover, FLAIR pulse sequences could diagnose some globe conditions, such as amelanotic uveal melanomas and malformations with no need of contrast agent administration. In contrast, they were useless to study deep ischemic areas, solid neoplasms, hemorrhagic lesions, poroencephalic areas, intrinsic medullary lesions and intra-orbital and extra-ocular conditions. In conclusion, the FLAIR technique is a major diagnostic tool in neuroradiologic MR studies because they overcome such limitations of Turbo SE PD sequences as blurring artifacts; moreover, their acquisition time is always very short. In some cases, FLAIR images are decisive for the diagnosis.

[Comparative assessment of conventional spin echo sequences and turbo spin echo in the study with magnetic resonance of the lesions of the spinal cord]. / Valutazione comparativa fra sequenze SE tradizionali e Turbo SE nello studio con Risonanza Magnetica delle lesioni del midollo spinale.

In the last few years, new magnetic resonance (MR) pulse sequences called Fast or Turbo Spin Echo (TSE) sequences have become available. This kind of T2-weighted images is particularly useful for the study of spondylosis and degenerative spinal conditions, because it both reduces involuntary motion artifacts and its acquisition time is shorter than that of conventional SE T2-weighted images. Our study was aimed at assessing the diagnostic gain of this new type of pulse sequences in intrinsic spinal cord conditions. Therefore, we acquired TSE and conventional SE sequences, consequently, in 36 patients with intrinsic spinal cord conditions, which were apparent on T2-weighted images, and then compared the sensitivity, contrast resolution, and depiction of lesion margins and extent in both acquisition techniques. The results of our study follow: even though all lesions were identified with both techniques, contrast resolution was higher with TSE than with conventional SE images. Lesion margins and extent were substantially equally depicted with both techniques. Finally, TSE sequences had the same, and sometimes even higher, diagnostic yield than conventional SE sequences: therefore, TSE can be considered the sequence of choice in the study of intrinsic spinal cord conditions.

Language disturbances from mesencephalo-thalamic infarcts. Identification of thalamic nuclei by CT-reconstructions.

The authors report the cases of two patients with CT-documented paramedian mesencephalo-thalamic infarcts, showing language disturbances. The first patient showed a non fluent, transcortical motor-like aphasia, the other had a fluent but severely paraphasic language disorder. The CT study disclosed that it was the dorso-median thalamic nucleus that was mostly involved in both cases. These findings agree with a few previous pathological studies suggesting that the paramedian thalamic nuclei, particularly the dorso-median nucleus may play some role in language disturbances. However the anatomical basis for thalamic aphasia remains speculative, taking into account the importance of cortical connections in the origin of subcortical neuropsychological disturbances.

High-dose contrast-enhanced computed tomography (CECT) with iopamidol in the detection of cerebral metastases. Tolerance of the contrast agent.

Intravenously administered iodinated contrast media have been demonstrated, since early experience with computed tomography of the brain, to improve clinical value of the procedure for detecting intracranial lesions. There is no universal agreement about the amount and the method of administration of the contrast medium. Many authors maintain that the use of large doses gives better results for the diagnosis of tumors and metastases. The purpose of this paper is to evaluate the tolerance of iopamidol administered by rapid intravenous infusion in a large number of patients undergoing contrast enhanced computed tomography to detect brain metastases. The authors examined 969 consecutive adult patients suffering from lung cancer, brain metastases have been detected in 17% of cases. Adverse reactions to contrast media occurred in 3 patients. Non ionic contrast media are recommended in this diagnostic procedure.

Iopamidol 150. A low iodine content non-ionic water-soluble contrast medium for CT myelocisternography.

Results of a clinical trial in CT myelocisternography performed with a new reduced concentration of iopamidol (150 mg I/ml) are reported. This compound is characterized by very low osmolality and osmotic pressure close to those of blood and CSF. Thirty patients were examined. Before, during and after the procedure pulse rate and blood pressure were recorded, EEG was taken and neurologic examination performed. After the examination no alteration in these parameters was recorded. The demonstration of the subarachnoid space and related structures was invariably adequate for diagnosis. In no case was a repeat study using a higher concentration of contrast medium needed. Mild reactions occurred only in three patients (10%). The authors conclude that iopamidol 150, owing to its safety and good imaging capacity, is useful in CT imaging of the subarachnoid space.

Computed tomography of the lumbar spine. Experience with an Expert System in computer aided diagnosis.

The authors report their experience in the formulation of an Expert System for computer aided diagnosis in the examination of the lumbar spine with computed tomography. A large number of steps are identified in the process of diagnostic evaluation of CT examinations; about 80 decisional rules are considered and arranged in five 'areas'. The Expert System under study is a first proposal, intended for use by radiologists with some basic training.

Applications of dynamic-CT, or angio-CT in neuroradiology. A disappointing experience.

The authors expose their experience in neuroradiological applications of dynamic-CT (D-CT) or angio-CT. The examinations are performed by means of a G.E. 8.800 CT/T. A special software offers automatic analysis of the region of interest. Vascular and tumoral patients are examined trying to evaluate: (a) the blood flow in patients suffering from transient ischaemic attacks and (b) to estimate the possibilities of D-CT in the evaluation of tumoral vascularity and in the identification of characteristic curves for different kinds of tumors.

CT evaluation of the lumbosacral spine.

The biologic cost-effectiveness of computed tomography (CT) versus myelography is so favorable to CT that it is now the method of choice for evaluating patients with less clear-cut clinical findings. CT is now used to detect lesions formerly difficult to diagnose, such as subluxation, arthrosis, facet osteophytes, and stenosis of the vertebral canal, as well as herniated disks and lateral disks. The findings in over 1,000 patients examined by CT for lumbosacral spinal pathology are documented. Associated or multiple abnormalities were present in about 60% of cases, with bulging or herniated disks occurring in 45% and 44%, respectively. Postsurgical arachnoiditis was seen in 43% of 64 patients studied for recurrence of symptoms after surgery.