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Biomedical subjects

M Mascalchi

Publications and source records attributed to M Mascalchi.

At least 91 records · Page 5Linked to original sources
PubMed1992

Rhabdomyosarcoma of the petrous ridge. CT and MR imaging in an atypical case with multiple cranial nerve palsy.

The CT and MR findings are reported in a case of biopsy proven rhabdomyosarcoma of the skull base. The tumor presumably originated in a pneumatized petrous ridge and had an atypical presentation of multiple cranial nerve palsy. The lesion exhibited a soft tissue density and a nonexpansile bone destruction on unenhanced CT. On MR imaging the lesion showed homogeneous intermediate signal intensity on T1 weighted images and a high signal intensity on proton density and T2 weighted images. The scanty literature on CT and MR features of rhabdomyosarcoma of the head and neck is reviewed.

Child, Preschool↗
PubMed1991

Delayed intracerebral hemorrhage after CSF shunt for communicating "normal-pressure" hydrocephalus. Case report.

A patient with arterial hypertension and a history of cerebrovascular accidents presented with communicating normal-pressure hydrocephalus. Two weeks after ventriculo-peritoneal CSF shunt he had a fatal intracerebral hemorrhage. Delayed intracerebral hemorrhage is an extremely rare complication of ventricular CSF shunting, the possible mechanisms of which are briefly discussed.

Aged↗
PubMed1991

Leukoaraiosis: a reappraisal. II. MRI studies.

Magnetic resonance imaging is more sensitive than computed tomography to brain white matter changes of undefined significance observed in elderly subjects termed leuko-araiosis. Cross-sectional clinical studies have shown that these changes are more frequent or are more extensive in patients with cerebrovascular disease or vascular risk factors. Pathological studies have revealed that a number of alterations may underlie focal white matter changes including complete and incomplete lacunar infarcts, état criblé, dilated perivascular (Virchow-Robin) spaces, demyelination, and gliosis. Diffuse white matter changes are more difficult to explain. These might result from confluence of focal changes, or from diffuse white matter ischemia (incomplete infarct). Alternatively, they may be related to alterations of the transependymal CSF flow. Longitudinal studies in asymptomatic subjects correlating the MRI picture with clinical, pathophysiological, and histopathological data are needed in order to establish the significance and prognostic value of the different processes underlying LA, and to plan therapeutic strategies to prevent or treat them.

Aged↗
PubMed1991

An analysis of the arterial input curve for technetium-99m-HMPAO: quantification of rCBF using single-photon emission computed tomography.

Arterial radioactivity content after the intravenous administration of HMPAO in seven human subjects was analyzed. Arterial sampling of 99mTc-HMPAO was performed on each subject over a 25-min period postinjection. The lipophilic fraction of the tracer present in the blood was rapidly extracted with octanol. An analysis of the time course of the extracted and nonextracted octanol fractions was performed in order to calculate the arterial input of the tracer available for brain extraction. HMPAO net regional brain clearances were then calculated and compared with rCBF values obtained in the same patients using 99mTc-microspheres injected into the left ventricle of the heart. HMPAO brain clearances were 0.41 +/- 0.01 and 0.27 +/- 0.01 ml/min/g for grey and white matter, respectively. Linear regression analysis was performed and the following result was obtained: clearance (HMPAO) = 0.07 + 0.43 . rCBF with a high significance (p less than 0.001). This equation can be used for the transformation of HMPAO clearances into rCBF values. Our study demonstrates that by using HMPAO and SPECT it is possible to obtain a quantitative estimate of rCBF in humans.

Adult↗
PubMed1990

Leuko-araiosis: a reappraisal. I. CT studies.

Leuko-araiosis is a purely descriptive term indicating images of bilateral, patchy or diffuse areas of decreased density frequently observable in the deep white matter on brain CT scans of adults and elderly subjects. While in earlier studies these images were considered as the "in vivo" expression of leukoencephalopathy associated with Binswanger disease, subsequently they have been reported in a rather broad spectrum of clinical conditions, including healthy aging and dementia of different types. Evidence of arterial hypertension and lacunar stroke is found in only two-thirds of subjects with leuko-araiosis. The results of pathological studies are conflicting about the nature of leukoencephalopathy, and the type and severity of medullary artery involvements. Probably several mechanisms underlie leuko-araiosis. They might act separately or be combined in different cases. Classification by physiopathological mechanism may be a suitable aim of future research in this field.

Aging↗
PubMed1990

Leukoaraiosis, intracerebral hemorrhage, and arterial hypertension.

To investigate whether the observed association of leukoaraiosis with intracerebral hemorrhage is direct or mediated by risk factors, we compared 116 patients with intracerebral hemorrhage confirmed by computed tomography and 155 controls without intracerebral hemorrhage, evaluating the prevalence of leukoaraiosis and vascular risk factors. Leukoaraiosis was observed in 21 (18%) of the 116 patients and in 12 (8%) of the 155 controls (p less than 0.01). Only two (6%) of the 31 patients with lobar hemorrhage had leukoaraiosis on computed tomograms, compared with 17 (24%) of the 71 patients with basal ganglionic hemorrhage (p less than 0.05). Leukoaraiosis was significantly correlated with intracerebral hemorrhage after controlling for age and sex by using multiple logistic regression analysis, while the correlation disappeared after controlling for hypertension. Our results indicate that leukoaraiosis is not an independent risk factor for intracerebral hemorrhage.

Brain↗
PubMed1990

Fast multiphase MR imaging of aqueductal CSF flow: 1. Study of healthy subjects.

Gradient-echo MR sequences are more sensitive to flow phenomena than spin-echo sequences are. We investigated aqueductal CSF flow by fast multiphase imaging. Fast multiphase imaging offers the opportunity to perform a dynamic study of fluid motion that is synchronous with the cardiac cycle. A section perpendicular to the cerebral aqueduct was imaged in 18 healthy volunteers. Serial, gated (every 50 msec from the ECG R wave), flow-compensated modulus images with 70 degrees-flip-angle excitation pulses were obtained with a single acquisition. The behavior vs time of CSF signal in the aqueduct was compared with that in the lateral ventricles. The former showed a peak at 0.47 +/- 0.1 fractions of a heart cycle after the R wave. No periodicity with the heart rate was observed for the ventricular CSF signal intensity. The mean CSF signal intensity in the aqueduct was found to range from about twice to three times that in the lateral ventricles over a cardiac cycle. Fast multiphase imaging is a sensitive and practical sequence for the MR investigation of aqueductal CSF flow. Its potential in patients with hydrocephalus is studied in a companion article.

Adult↗
PubMed1990

Fast multiphase MR imaging of aqueductal CSF flow: 2. Study in patients with hydrocephalus.

The signal intensity in the region corresponding to the cerebral aqueduct was evaluated in three patients with noncommunicating tension hydrocephalus (caused by aqueductal obstruction in two and type I Arnold-Chiari malformation in the other), seven patients with suspected normal-pressure hydrocephalus (three of whom subsequently underwent successful shunting), and 10 patients with ex vacuo (atrophic) hydrocephalus. A gradient-echo MR sequence, called fast multiphase imaging, was used. Serial images corresponding to different phases of the cardiac cycle were acquired. No flow-related enhancement was observed over the entire cardiac cycle in the patients with noncommunicating hydrocephalus. Patients with normal-pressure hydrocephalus showed a higher aqueductal CSF signal intensity, consistent with increased systolic flow rates, than patients with ex vacuo hydrocephalus. When comparing the above two groups of patients with a control group of healthy volunteers, significantly higher and lower values of the (mean) maximum aqueductal signal intensity were found in the normal-pressure hydrocephalus patients and the ex vacuo hydrocephalus patients, respectively. Fast multiphase MR evaluation of aqueductal CSF flow may help to differentiate patients with different types of hydrocephalus.

Adult↗
PubMed1990

Subcortical arteriosclerotic encephalopathy: single photon emission computed tomography-magnetic resonance imaging correlation.

Regional cerebral blood flow was studied using 99mTc-HM-PAO and single photon emission computed tomography (SPECT) in five healthy subjects and in eight patients with clinical and computed tomography (CT) features of subcortical arteriosclerotic encephalopathy. All the patients and controls underwent magnetic resonance imaging (MRI). Circumscribed cortical hypoperfusion was observed in three patients, and in one case there was no evidence of cortical or sulcal alterations on MRI. In all the patients, a reduction of the white matter perfusion was found in periventricular and/or supraventricular regions. This pattern was substantially correlated with the typical white matter hyperintensities shown by MRI scans. These findings support the hypothesis that white matter hypoperfusion is the most prominent functional abnormality in subcortical arteriosclerotic encephalopathy.

Aged↗
PubMed1989

Computed tomography, magnetic resonance imaging and pathological correlations in a case of Binswanger's disease.

The results of 3 computed tomography (CT) examinations carried out over a 7 year period and of a post-mortem magnetic resonance (MR) study showed aspects of a white matter disease in a hypertensive patient suffering from vascular dementia. Histopathology revealed the primary cause of dementia to be a white matter degeneration sparing the U fibers. Rarefaction of both the myelin sheaths and the axons was present together with severe thickening of the medullary arteries. These findings support the existence of Binswanger's disease (BD) as a distinct variety of arteriosclerotic dementia. CT and MR imaging are valuable aids for diagnosis. However, since there are many other causes of CT and MR demonstrated diffuse white matter degeneration in the elderly, a conclusive diagnosis of BD requires pathological confirmation.

Dementia, Vascular↗
PubMed1989

Histopathological correlates of leuko-araiosis in patients with ischemic stroke.

A neuropathological study was carried out in 4 cases of ischemic stroke with leuko-araiosis (LA), 3 cases of clinically suspected Binswanger's subcortical arteriosclerotic encephalopathy (SAE) also showing LA, and 3 cases without LA. Unlike the SAE cases, in 3 of the cases in the first group the white matter changes corresponding to LA could not be explained by ischemic mechanisms related to small vessel changes.

Aged↗
PubMedDate not supplied

Breath-hold spin-echo MR imaging for evaluation of dynamic enhancement of native and treated hepatocellular carcinoma after intravenous Gd-DTPA administration.

Using a simple modification of a standard spin-echo sequence which enable acquisition of three breath-hold images in 15 s, dynamic enhancement of 30 histologically proven hepatocellular carcinomas (17 native tumors, 6 completely necrotic tumors after nonsurgical treatments, and 7 tumors with viable and necrotic portions) after intravenous injection of gadolinium-DTPA was evaluated. Native hepatocellular carcinomas and viable portions in treated nodules showed elective enhancement in images obtained 40 s after contrast injection. Contrast between these lesions and the normal liver decreased thereafter. No contrast uptake was seen in entirely necrotic nodules and necrotic portions of treated nodules. Because of the capability to demonstrate the elective arterial blood supply typical of hepatocellular carcinoma, breath-hold T1-weighted spin-echo sequence should replace conventional T1-weighted images for the evaluation of intravenously administered gadolinium-DTPA enhancement of this tumor before and after nonsurgical treatments.

Aged↗
PubMedDate not supplied

Liver and spleen enhancement after intravenous injection of carboxydextran magnetite: effect of dose, delay of imaging, and field strength in an ex vivo model.

It has been predicted that liver and spleen enhancement after administration of superparamagnetic contrast agents may be different, depending on the strength of the main magnetic field. With the use of an ex vivo model, we investigated at 0.3, 0.5, and 1.5 T the effects on liver and spleen signal intensity of 5, 15, and 45 mumol/kg body weight of dextran magnetite (SHU 555A) in 54 rats. Nine rats served as controls. At different time delays since injection, the animals were killed, and after perfusion with saline, the liver, brain, and spleen were fixed in formalin. The specimens were embedded in an agar gel matrix and imaged with inversion recovery T1-weighted, proton density spin echo, and T2*-weighted gradient recalled echo (GRE) sequences. At each magnetic field strength, peak liver and spleen signal loss increased with increasing dose of the contrast medium. Signal loss was significantly more conspicuous after a dose of 15 than 5 mumol/kg body weight, but not after a dose of 45 compared with 15 mumol/kg. No signal change was observed in the brain. GRE images showed higher enhancement than proton density-weighted spin echo and inversion recovery images but were noisier. The enhancement showed a plateau between 30 min and 24 hours. Only the signal decrease of the liver after a low dose of contrast medium on GRE images was significantly higher (p < 0.01) at 1.5 than at 0.5 and 0.3 T. Other differences in respect to the field strength were less significant (p < 0.05) or nonsignificant. Differences in the spleen enhancement were nonsignificant. SHU 555A at a dose of 15 mumol/kg is an efficient intracellular contrast agent for liver and spleen at low, mid, and high field strength. Proton density spin echo images are probably the sequence of choice to exploit SHU 555A contrast effects and a wide time window for imaging after its intravenous injection does exist.

Animals↗
PubMedDate not supplied

Solitary necrotic nodule of the liver: imaging and correlation with pathologic features.

We describe two cases of solitary necrotic nodule of the liver, an uncommon nonmalignant lesion that can mimic a metastasis. The nodule appeared hypoechoic, or targetlike, on sonography, hypodense without contrast enhancement on computed tomography, and hypointense on magnetic resonance imaging, including diffusion-weighted images. These features, peculiar when considered together, are explained by the coagulative type of necrosis.

Adult↗
PubMedDate not supplied

Small hepatocellular carcinoma: differentiation from adenomatous hyperplasia with color Doppler US and dynamic Gd-DTPA-enhanced MR imaging.

BACKGROUND: To investigate the usefulness of color Doppler ultrasound (US) and dynamic Gd-DTPA-enhanced magnetic resonance (MR) imaging in the differentiation of small hepatocellular carcinoma (HCC) and adenomatous hyperplasia (AH). METHODS: Thirty-eight small (3 cm or less) nodular lesions (in 38 cirrhotic patients) with US features consistent with HCC underwent evaluation with color Doppler US and MR imaging. Breath-hold T1-weighted rapid acquisition spin echo MR sequence after bolus injection of 0.1 mmol/kg gadopentetate dimeglumine was used to evaluate dynamic enhancement. US-guided tissue-core percutaneous biopsy established the diagnosis: HCC in 28 cases and AH in 10. RESULTS: Color signals with pulsatile or continuous Doppler spectrum were demonstrated in 19 of 28 HCCs (68%) but in none of the AHs. Although there was considerable overlap in signal intensity between HCC and AH on both unenhanced T1- and T2-weighted images, early enhancement on breath-hold T1-weighted images obtained 40 s after starting contrast administration was observed in 22 of 28 HCCs (79%) but in none of the AHs. In 26 of 28 HCCs (93%), pulsatile or continuous flow at color Doppler US, early enhancement at dynamic MR imaging, or both were observed. CONCLUSION: Findings with color Doppler US and dynamic Gd-DTPA-enhanced MR imaging enable a reliable distinction between small HCC and AH.

Biopsy↗
PubMedDate not supplied

Electric and CO2 laser SEPs in a patient with asymptomatic syringomyelia.

We recorded electrically stimulated somatosensory evoked potentials (electric SEPs) and pain-related SEPs following CO2 laser stimulation (CO2 laser SEPs) from a 17-year-old patient affected by myotonic dystrophy whose MRI disclosed a large syrinx extending from spinal level C2 to S3. Careful clinical and electromyographic examinations revealed no motor or sensory disturbances, apart from myotonia. The only abnormality noted in median and ulnar nerve short-latency electric SEPs (recorded with a non-cephalic reference electrode) was the absence of cervical component N13, the other SEP responses (N9, N10, N11, P14, N20) being normal. The cutaneous pain threshold and CO2 laser SEPs (both obtained by a CO2 laser beam applied to the back of the hand) were normal. Thus cervical component N13 appears to be highly sensitive to the effects of central cord lesions, even when these are asymptomatic.

Adolescent↗
PubMedDate not supplied

MR imaging in a case of Hallervorden-Spatz disease.

Magnetic resonance using a 0.5 T system and a T2-weighted spin-echo pulse sequence revealed symmetric areas of marked hypointensity of the globi pallidi in a case with a family history of and presenting with clinical features consistent with Hallervorden-Spatz disease. No such findings were seen in any of 16 normal volunteers of similar age. Magnetic resonance may be useful for diagnosing Hallervorden-Spatz disease.

Adult↗