Intracranial Masses with Perilesional Edema: Differential Diagnosis with Perfusion CT.

Perilesional edema (PE) is commonly observed in association with an intracranial mass. PE is thought to be determined by vasogenic effects in the cerebral parenchyma surrounding the mass due to the loss or absence of the blood-brain barrier (BBB) inside the lesion. Alterations in capillary permeability induce extrusion of fluids into the extravascular space around the mass. On Computed Tomography (CT) PE corresponds to an area of low density for the increased water content, outside the margins of the lesion. It is difficult to differentiate PE from areas of parenchymal compressive ischemia and sometimes the two events could be associated. A solitary mass with PE is more commonly discovered on a non-enhanced computed tomography (NECT) study performed for the onset of stable or rapidly progressive neurological symptoms. In such cases, a supplementary CT scan with contrast (CECT) is generally indicated to complete the baseline imaging before MRI. Contrast enhancement is generally present in a mass with PE and it is not specific for differential diagnosis. Perfusion computed tomography (PCT) requires a few minutes in addition to the time needed for CECT. PCT may give information on regional microvascular density, permeability and blood flow, thus it may play a role when tumoral neo-angiogenesis or non-neoplastic altered haemodynamics are suspected. We therefore investigated the utility of PCT in the differential diagnosis of the intracranial solitary masses with PE.

CT in acute stroke: improved detection of dense intracranial arteries by varying window parameters and performing a thin-slice helical scan.

We evaluated the possibility of improving detection of a dense intracranial artery on CT in acute stroke by narrowing window width, varying window level and performing a thin-slice helical scan for the circle of Willis, in some cases followed by postprocessing maximum-intensity projections. We carried out 32 examinations of 31 patients with a documented cerebral ischaemic attack, performing cranial CT within 6 h of the onset of symptoms. Patients with intracranial haemorrhage were excluded, as were patients who went on to thrombolytic therapy. Varying window width and centre level on standard 5 mm thick contiguous axial slices, we detected a dense proximal middle cerebral artery (MCA) in a higher proportion of patients. A 1.1 mm thick helical scan through the circle of Willis improved recognition of a dense distal horizontal segment and the temporoinsular branches of the MCA and of a dense posterior cerebral artery.

[Assessment of contrast enhancement in solitary pulmonary nodules studied with spiral computerized tomography. Preliminary results]. / Valutazione dell'accentuazione del contrasto del nodulo polmonare solitario studiato con Tomografia Computerizzata spirale. Risultati preliminari.

This study was aimed at assessing the clinical usefulness of measuring the contrast enhancement (CE) of solitary pulmonary nodules (SPN) in distinguishing benign from malignant lesions. We used spiral CT to study prospectively 35 pulmonary lesions presenting as SPNs < 30 mm phi; we evaluated the CE of the nodules 120 minutes after the administration of 100 mL of nonionic contrast material (= 30 grams of iodine), at 2 mL/s. The final diagnosis of the 35 SPNs was made at surgery (27 cases); positive sputum cytology (2 cases), 12 months' follow-up (5 cases) or fine-needle aspiration biopsy and 6 months' follow-up (1 case). Thus, 25 of 35 SPNs proved malignant (11 adenocarcinomas, 5 squamous cell carcinoma, 2 large cell carcinomas, 2 carcinoids, 1 small cell carcinoma, 2 cases with positive sputum cytology, 2 metastases) and the extant 10 of 35 proved benign. Malignant nodules enhanced markedly more (mean value: 36.8 HU) more than benign lesions (mean value: 18.6 HU). CE exceeded 20 HU in 23/25 malignant nodules and did not in 2/25; it did not exceed 20 HU in 6/10 benign nodules and did in 4/10. With 20 HU as the threshold value for a positive test (malignancy), sensitivity was 92%, specificity 60% and accuracy 83%; positive and negative predictive values were 85% and 75%, respectively. In conclusion, CE evaluation is a sensitive, although not very specific, indicator of malignancy in SPNs.

[The radiodiagnosis of bone metastases from melanoma]. / Contributo alla radiodiagnostica delle metastasi ossee da melanoma.

The records of 3,795 cases of malignant melanoma treated at the INT (Milan) from 1975 to 1992 were reviewed. Histologic confirmation was obtained in all cases. Thirty-one patients (0.82%) with solitary or multiple skeletal metastases were identified. The review of conventional films, tomograms, CT, MR and bone scintigraphy images enabled us to detect 120 single bone lesions. The X-ray features were divided into two groups according to typical and atypical skeletal lesions. Typical bone metastases are osteolytic (87.5%), with medullary origin (91.6%), and they cannot be distinguished from other osteolytic metastases on the basis of imaging criteria alone. Lesion growth causes cortical erosion and destruction (46.6%), pathologic fractures (22.5%) and soft tissue involvement (12.5%). Lytic areas usually have ill-defined margins. Clear-cut outline is an uncommon finding. Atypical skeletal metastases exhibit a mixed osteolytic-osteoblastic pattern (10%), which is hardly ever completely osteoblastic (2.5%). Other unusual metastatic patterns include intense trabecular rarefaction with no detectable single lesion (3.3%), the presence of a well-defined sclerotic rim and periosteal reaction (12.5%). Atypical growth may cause extensive cortical destruction and periosteal production resembling osteogenic osteosarcoma. The various imaging methods show that conventional radiology has relatively poor sensitivity because of anatomical reasons, while MRI is the most sensitive method to detect skeletal localizations. Treatment changes the radiologic patterns of the lesions: recalcification, sclerotic rim, periosteal reaction are common response patterns. Finally, in spite of the above limitations, conventional radiology remains the method of choice to assess lesion evolution during the follow-up.