Fatty infiltration of the liver. Quantification by 1H localized magnetic resonance spectroscopy and comparison with computed tomography

RATIONALE AND OBJECTIVES

The authors evaluated the degree of fatty infiltration of the liver in subjects with diffuse liver steatosis using image-guided 1H localized MR spectroscopy and correlated the magnetic resonance (MR)-determined fat fraction with the computed tomography (CT) liver/spleen density ratio and histologic evaluation.

METHODS

MR measurements were performed at 1.5 T by applying a double-spin-echo localization sequence. Twenty-six patients underwent MR and CT examinations and ultrasound (US)-guided biopsy. Additionally, three healthy volunteers underwent MR examination. Steatosis severity was estimated using 1) the ratio between fat and total MR signal areas; 2) the ratio between liver and spleen CT number; and 3) histologic score.

RESULTS

The linear correlation between MR fat/fat-plus-water signal ratio and CT liver/spleen density values ratio is statistically significant. Both techniques correlate well with histologic score. No significant correlation exists between water or fat T2 values and the severity of steatosis.

CONCLUSIONS

1H MR spectroscopy allows a noninvasive estimate of the hepatic fat content.

Nicotinamide mononucleotide adenylyltransferase activity in human erythrocytes

Nicotinamide mononucleotide adenylyltransferase (NMN-AT) activity has not hitherto been demonstrated in human red blood cells, owing to its low activity. Since it is usually located in the nucleus, the possibility of finding it in human erythrocytes was excluded. Here we report the first demonstration and characterization of NMN-AT in human red blood cells, by an HPLC method. The enzyme is Mg2+ dependent, with a Km of 0.303 mM for nicotinamide mononucleotide and 0.103 mM for ATP, and a Vmax of 346 nmol g Hb-1 h-1. The crude preparation is also active on nicotinic acid mononucleotide, producing nicotinic acid adenine dinucleotide. NMN-AT activity is inhibited by nicotinic acid mononucleotide, and nicotinic acid adenylyltransferase is inhibited by nicotinamide mononucleotide. Fiftyfold purification of NMN-AT was achieved by DEAE-Toyopearl chromatography, and the kinetic characteristics were determined. The partially purified preparation maintained its nicotinic acid adenylyltransferase activity. These findings are discussed in light of the regulation of NAD metabolism in human red blood cells.

Alzheimer's disease histologically proven studied by MRI and MRS: two cases

Two patients affected by severe Alzheimer's disease (AD) were investigated by MRI and image-guided 31P MRS. In one case, 1H MRS was additionally performed. In both cases the diagnosis of AD was confirmed, post mortem, by the pathologist. The spectral parameters of the 31P MR spectra were estimated by fitting the 31P MR signals in the time domain. Our 31P MRS results suggest that it is possible to detect the membrane catabolism, as indexed with the level of PDE resonances visible in in vivo 31P MRS, at least in severe AD cases. The 1H spectrum from AD brain showed a marked decrease of NAA signal respect to choline.

Quantitative 31P MRS of the normal adult human brain. Assessment of interindividual differences and ageing effects

The characteristics of the 31P MR spectra from a large central volume in the brain of 47 healthy adults (aged 25-85 years) were assessed. Spectral parameters were estimated by means of a time-domain fitting technique. Statistical uncertainties of the estimates were determined by means of the Cramer-Rao theory and minimized by introducing a priori knowledge into the fitting procedure. Age-dependency of the spectral parameters was assessed by means of linear regression. Significant differences between individuals were established for some parameters. A significant age-dependency (p < or = 0.001) of ca 20% over the age range considered was found for the intensity of the phosphocreatine resonance line.

Primary osteogenic sarcoma of the posterior mediastinum. Case report

Extraosseous osteogenic sarcoma of the mediastinum is an extremely rare tumour, usually arising in the anterosuperior compartment. Clinical findings in the first reported case of high-grade osteogenic sarcoma arising in the posterior mediastinum are described.

Magnetic resonance imaging in right ventricular dysplasia

Fifteen patients with right ventricular dysplasia were investigated by T1-weighted spin- and gradient-echo pulse sequences, using a protocol that enabled both a subjective analysis of myocardial signal intensity and a quantitative/qualitative analysis of right and left ventricular function. In 8 patients, 3 investigators independently recognized abnormally hyperintense areas in the anatomic sites usually affected by the disease. In 7 of these patients, these areas showed an overlap with a-dyskinetic areas imaged by both magnetic resonance imaging (MRI) and echocardiography. In 1 patient who underwent a cardiac transplant, MRI of the explanted heart showed an excellent correlation between the distribution of the lesions and the in vivo/in vitro features. The data were compared with those from an equivalent sample of patients affected by dilated cardiomyopathy. In the latter patients, no focal hyperintensities were attributed to any anatomic sites in the right ventricule, and no focal a-dyskinetic foci were observed. Furthermore, the 2 groups of patients were significantly different in regard to dimensional and functional quantitative parameters. The results suggest that MRI is useful in integrating echocardiographic data and can be helpful in diagnosing this disease in late stages.

Accuracy of in-vivo assessment of prostatic volume by MRI and transrectal ultrasonography

More accurate noninvasive estimation of prostate size is important in therapeutic trials for benign prostatic hyperplasia. The accuracy of MRI and transrectal ultrasound (TRUS) in assessing prostate weight was evaluated in 48 patients who underwent radical prostatectomy for stage A or B cancer. The volume derived from the wet weight of the freshly excised specimen was used as a reference. We compared that volume with volume estimates derived from the three-axis linear dimension measurement by MRI and TRUS using a tissue density of 1.05 g/cc and the standard formula for an ellipsoid object. Prostate and seminal vesicle volumes were also computed by contouring T2-weighted 5 mm thick contiguous MR images using a semiautomatic edge detection program and pixel summation. Three-axis volume MRI method versus volume from wet weight has slightly less scatter than TRUS three-axis method (r = 0.85 vs r = 0.81). Contoured MR volume method has the least scatter r = 0.93, statistically better than the linear axis method. Contoured MRI volumetric analysis appears superior to linear MRI or TRUS methods in estimating true prostate volume.

Clinical and metabolic effects of a triphasic pill containing gestodene

The clinical and metabolic effects of a low-dose triphasic oral contraceptive containing gestodene were investigated in 42 healthy women during 6 months of treatment. No pregnancies and no severe side effects occurred during the study. The pill exerted good cycle control and the incidence of irregular bleeding was very low. As for the coagulatory system, there was an increase in prothrombin activity and in fibrinopeptide A plasma levels, and a decrease in activated partial thromboplastin time. Antithrombin III activity, fibrinogen concentration and platelets count did not change during pill intake. No significant modifications in plasma total-cholesterol, low density lipoprotein-cholesterol or in the subfraction high density lipoprotein2-cholesterol (HDL2-CH) were observed. Serum triglycerides, HDL-CH and HDL3-CH levels were significantly higher at the end of treatment. The pill did not alter fasting insulin and glucose levels or their response to an oral glucose tolerance test. These minimal effects on metabolism, combined with its high efficacy and acceptability, may suggest that this triphasic formulation with gestodene seems to be a safe and reliable contraceptive agent.

Effects of low-dose steroids on bronchial healing after sleeve resection. A clinical study

We prospectively evaluated the effect of low-dose steroids after bronchial sleeve resection in 20 consecutive patients. Ten patients (group I) did not receive steroids. Ten patients (group II) received 10 mg of methylprednisolone intravenously intraoperatively and 10 mg intramuscularly every day for 10 days. In addition, group II patients received 250 mg of hydrocortisone succinate endobronchially before extubation and 5 mg of methylprednisolone daily in an aerosol solution. Bronchoscopy was performed in all patients before extubation, every day for 10 days, and 1 and 3 months after the operation. Bronchial healing was graded endoscopically from grade I (no edema, excellent healing) to grade V (dehiscence). In group I, three patients showed grade I, four had grade II, one indicated grade III, one revealed grade IV (granuloma), and one showed grade V (dehiscence) healing. Mean postoperative hospital stay was 9.7 days. In group II all 10 patients showed grade I healing. Mean postoperative hospital stay was 7.3 days. We conclude that low-dose steroids improve the postoperative course in patients undergoing bronchial sleeve resection.

Needlestick injury in hospital personnel: a multicenter survey from central Italy. The Latium Hepatitis B Prevention Group

OBJECTIVES

To assess the rate of needlestick injury in hospital personnel in an Italian region. To identify risk factors potentially amendable to correction.

DESIGN

Hospital workers undergoing hepatitis B prevaccination testing in 1985 through 1986 were interviewed regarding needlestick injury in the previous year, job category, area of work, years of employment, and other pertinent information.

SETTING

Of the 98 public hospitals of the Latium region, 68 participated in the survey: 32 of 55 with less than 200 beds, 20 of 25 with 200 to 300 beds, 11 of 13 with 400 to 900 beds, and all of the 5 with more than 1,000 beds.

PARTICIPANTS

All healthcare workers providing direct patient care or environmental services as well as student nurses were invited by the hospital directors to undergo hepatitis B prevaccination testing and vaccination, if eligible.

RESULTS

Of 30,226 hospital workers of the 68 participating hospitals, 20,055 were interviewed (66.3%): 47.7% of the 7,172 doctors, 71% of the 14,157 nurses, 55.9% of the 2,513 technicians, and 71.9% of the 6,384 ancillary workers. Needlestick injury was recalled by 29.3%; the rates were 54.9%, 35.3%, 33.8%, 26.5%, 18.7%, and 14.7% in surgeons, registered and unskilled nurses, physicians, ancillary workers, and technicians, respectively. The recalled injury rate was 39.7% and 34.0% in surgical and intensive care areas; in infectious diseases, it was 16.7%. Rates were lower in hospitals with 200 to 300 beds (25.6%). The needlestick injury rate declined from 32% in those with less than 5 years of employment to 28% in those with more than 20 years (p less than .01). Prevalence of HBV infection was higher in student nurses and young workers recalling a needlestick exposure (14.3% and 15.8%, respectively), versus 10.1% and 12.8% in those not exposed (p less than .01 and less than .05, respectively).

CONCLUSIONS

Parenteral exposure to blood-borne infectious agents is a relevant risk among healthcare workers in our region, particularly in defined job categories and hospital areas (surgeons, nurses, surgical, and intensive care areas). Immunization and educational efforts should be made along with better designs of devices to reduce the risk of infection.

ACE inhibition in diabetic patients: effect on pressor responsiveness to noradrenaline

The pressor responsiveness to noradrenaline was assessed before and after four weeks of treatment with enalapril (20 mg/day) in eight mild-to-moderate essential hypertensives, in eight normotensive type II diabetics and in eight mild-to-moderate hypertensive type II diabetic patients. The ACE inhibitor interfered to the same extent with the renin-angiotensin system and did not alter noradrenaline kinetics in the three groups of patients, but significantly reduced the arterial responsiveness only in non-diabetic subjects. It is suggested that factors, such as an exaggerated sodium retention, might determine the lack of effect of enalapril in diabetic patients.

[Magnetic resonance in trigeminal neuralgia]

One of the possible causes of the so-called "essential" trigeminal neuralgia is a neurovascular compression of the fifth cranial nerve root at the pons. The demonstration of this hypothesis could orientate the surgical treatment to microvascular decompression. In order to evaluate the role of MRI in the diagnosis of trigeminal neuralgia due to neurovascular compression, the authors present the results of a prospective evaluation of the cranial MR studies of 18 neuralgic patients in comparison with a retrospective evaluation of the cranial MR studies of 50 healthy control subjects. The results show that neurovascular compression can be demonstrated in 83.3% of the neurological patients. In all cases a good correlation between the clinical symptoms, the side of positive MR findings and the surgical findings, when available, was demonstrated. On the other hand, neurovascular compression was demonstrated in 28% of the healthy control subjects. The authors conclude that neurovascular compression can be demonstrated in a high percentage of patients with the so-called "essential" trigeminal neuralgia. Compared with the other imaging modalities (angiography, Computed Tomography) MRI is the best technique in the diagnosis of this disease. In fact, MRI is not only able to differentiate the symptomatic from the essential type of neuralgia, but is also very sensitive in the identification of trigeminal neuralgia due to neurovascular compression. This diagnosis could direct the surgical treatment to microvascular decompression.

[Single lung transplantation: experimental technique and functional results]

Single lung transplantation was performed in 22 pigs. The first 10 experiments were devoted to settle the surgical technique: in these cases we employed small animals (8-12 kg); technical difficulties and the high incidence of perioperative complications induced us to utilize bigger animals (greater than 20 kg) in the subsequent experiments. In the recipient, after left pneumonectomy we prepared the right pulmonary artery and encircled it with an inflatable silicon cuff connected to a reservoir positioned outside the chest cavity of the animal. The inflation of the cuff allows the complete occlusion of the right pulmonary artery and thus the functional evaluation of the isolated transplanted lung. Perioperative functional evaluation has been performed at different times till the third postoperative day, documenting the good status of the transplanted lung. This study confirms the possibility to employ pigs for experimental single lung transplantation to settle the surgical technique with economic and organizing advantages. Furthermore, it confirms the good results achieved in the dog, in which the occlusion of the contralateral pulmonary artery by means of an inflatable silicon cuff allows to evaluate the isolated transplanted lung function.

[Clinical magnetic resonance spectroscopy. The state of the art]

Magnetic resonance spectroscopy is a noninvasive technique which allows the study of the chemical composition of tissue. In the first part of this paper the authors describe the physical principles and the technical features of spectroscopy, including spectral acquisition, localization techniques and peak quantification. The second part of the paper regards the evaluation of the biological significance of the peaks observed in the most frequently studied spectra (31P and 1H). The third part concerns the clinical feasibility of magnetic resonance spectroscopy: in order to employ spectroscopy in the clinical practice, this technique should be able to fulfill such requirements as tissue characterization, metabolic quantification, therapy follow-up, biochemical understanding of the physiopathologic phenomena and pH evaluation. The fourth and last part of this paper deals with the clinical applications of spectroscopy. The authors consider the results of other research groups in the spectroscopic evaluation of the striate muscle, the central nervous system, heart, liver and some other organs. Then they describe some preliminary personal results in cerebral spectroscopy (41 healthy subjects studied with 31P and 5 with 1H) and liver spectroscopy (19 healthy subjects studied with 31P and 9 healthy subjects and 9 patients with liver steatosis studied with 1H). The authors conclude that the problem of the potential clinical application of spectroscopy is still open. So far the use of this technique is limited to research centers, which should point out the clinical role of spectroscopy.

Computed tomography for preoperative assessment of T3 and T4 bronchogenic carcinoma

Between January 1986 and January 1991, 175 patients with suspected T3 or T4 bronchogenic carcinoma underwent computed tomographic (CT) examination of the chest before thoracotomy. We considered two groups of patients: group 1 includes 98 patients with a paramediastinal mass on standard chest X-ray; invasion of hilar and mediastinal structures was preoperatively investigated with CT and then assessed at thoracotomy. The sensitivity, specificity and accuracy were 72%, 75% and 73%, respectively; positive and negative predictive values were 71% and 76%. In group 2 77 patients had a peripheral tumor suspected of invading the parietal pleura and the soft tissues of the chest wall (patients with evident rib or vertebral invasion were not included). Sensitivity, specificity and accuracy of CT were 52%, 86% and 71%, respectively; positive and negative predictive values were 74% and 70%. We conclude that CT with injection of contrast material is indispensable when direct lung cancer infiltration must be ruled out; its accuracy is however not sufficient to be relied upon in all patients.

[Cardiac magnetic resonance. Optimization of the parameters in the evaluation of right and left ventricular function]

MR imaging is the only non-invasive tomographic imaging modality capable of imaging the heart along planes that are parallel to each other and in any desired direction. Such reconstruction algorithms can thus be applied to MR images as the Simpson's rule which allows volume estimation of all cardiac cavities, although very irregular in shape, like the right ventricle. The authors optimized the technical parameters to obtain a set of multiphase double-angulated images on both the short and the long axes of the heart, in about 1-hour time. This technique was used to examine 31 patients suffering from several cardiopathies. The images allowed both end-diastolic and end-systolic volumes to be estimated, as well as the ejection fractions of both ventricles. In the left ventricle the area-length method and the Simpson's rule were applied, whereas only the latter was employed in the right ventricle. The correlation coefficients of US and MR data were, for the 3 parameters, r = 0.813, r = 0.920, and r = 0.879, respectively, in the first case, and r = 0.905, r = 0.923, and r = 0.890 in the second one. The time required to analyze the obtained data, which is done manually, is still considerably long.

'Organoid' thymoma: a well-differentiated variant with distinctive clinicopathological features

The present paper describes the clinical, histological and immunohistochemical features of five cases of 'organoid' thymoma. The histological hallmark of this lesion is the prominent and diffuse 'organoid' pattern, defined by the presence of several areas of medullary differentiation. These areas, which are strictly reminiscent of the medullary area of the normal thymus, are scattered within a neoplastic tissue resembling the thymus cortex, the overall appearance mimicking that of normal thymus. All cases shared common clinical features; they were non-invasive or minimally invasive tumours arising in young or middle-aged female patients. Although the incidence of 'organoid' thymoma is low (5.2% in our series), our morphological, immunohistochemical and clinical data suggest that this peculiar tumour may represent a well-differentiated variant of thymoma, with low-grade aggressiveness and a distinct clinicopathological profile.

The effect of ace inhibition on peripheral hemodynamics in normotensive and hypertensive patients with type II diabetes

The effect of treatment with enalapril (10 days at 10 mg/d followed by 4 weeks at 20 mg/d) on forearm hemodynamics was assessed in eight normotensive patients and eight patients with hypertension affected by Type II diabetes as well as in eight patients with essential hypertension and normal glucose tolerance. The ACE inhibitor decreased regional vascular resistances and increased the maximum arteriolar-vasodilating capacity and venous distensibility in the three groups of patients. Thus, this study shows that ACE inhibition by enalapril improves regional hemodynamics in patients with Type II diabetes.