Stavros C. Efremidis

The multistep process of hepatocarcinogenesis in cirrhosis with imaging correlation

Abstract. Hepatocarcinogenesis in the cirrhotic liver has recently become a subject of intense investigation. The development of hepatocellular nodules demonstrating varying degrees of cellular and architectural atypia suggests that these nodular lesions represent a pathway of carcinogenesis in cirrhosis of different etiologies. This pathway involves processes, such as capillarization and neoangiogenesis, leading to a gradual change in blood supply from portal to arterial, as a dysplastic nodule becomes hepatocellular carcinoma. These changes in intranodular blood supply create different enhancement patterns in the two phases of liver circulation after an intravenous contrast injection on multi-phase helical CT or dynamic gadolinium-enhanced MRI. This article reviews the current concepts regarding the vascular changes occurring in dysplastic nodules in the multistep process of hepatocarcinogenesis, along with the associated imaging manifestations. Some practical issues and dilemmas regarding the follow-up and biopsy of these lesions are also discussed.

The clinical significance of aortic compliance and its assessment with magnetic resonance imaging.

The biophysical properties of the aortic wall seems to play a significant role in the pathogenesis of cardiovascular disease such as atherosclerosis, hypertension, aneurysm formation, Marfans syndrome, and in normal aging. The presence and the proportion of smooth muscle, collagen, and elastin proteins contribute to the compliance of the vessel wall with the latter being the most extensible component. However, elastin fibers fracture at low stresses contributing to a decrease of the aortic compliance and consequently to an elevation of the pulse pressure, which is a risk factor of cardiovascular disease. Early detection of a decrease in the aortic compliance could help to identify early cardiovascular disease in asymptomatic patients and monitor the results of the therapeutic interventions. Therefore, estimation of the aortic compliance can be used for both screening as well as long-term follow-up. Magnetic resonance imaging which is a noninvasive, accurate, and reproducible method can estimate the compliance of the aortic wall either by measuring the relative change in cross sectional area of a chosen segment using ECG-triggered spin echo or gradient echo sequences or by measuring the pulse wave velocity through the aorta using the phase contrast-magnetic resonance imaging (PC-MRI) technique. Both techniques have been validated and many sudies suggest MRI as a valuable tool for evaluating aortic wall function. However, large prospective studies are mandatory for the method to be established as a screening tool.

MRI in the Histologic Characterization of Testicular Neoplasms

OBJECTIVE The purpose of our study was to investigate the potential role of MRI in the preoperative characterization of the histologic type of testicular tumors and, more specifically, to differentiate seminomatous from nonseminomatous testicular neoplasms. MATERIALS AND METHODS Twenty-one patients with histologically proven germ cell testicular tumors underwent MRI of the scrotum on a 1.5-T unit. T2- and T1-weighted sequences before and after i.v. administration of gadolinium chelate were performed. MRI studies were retrospectively reviewed by two radiologists and findings were correlated with the histopathologic diagnosis. An attempt was made to differentiate seminomatous from nonseminomatous testicular tumors on the basis of signal intensity and homogeneity of the lesions, presence of fibrovascular septa, tumor encapsulation, and patterns of contrast enhancement. Interobserver agreement was assessed using weighted kappa statistics. RESULTS MRI findings correctly characterized 19 (91%) of 21 testicular neoplasms (nine seminomatous and 10 nonseminomatous testicular tumors), with excellent interobserver agreement. The presence of an intratesticular lesion of predominantly low signal intensity on T2-weighted images, with septa enhancing more than tumor tissue after contrast material administration, was more suggestive for the diagnosis of a seminoma. Tumors that were markedly heterogeneous both on unenhanced and contrast-enhanced images were indicative of a nonseminomatous neoplasm. CONCLUSION Our study shows that MRI provides a credible preoperative differentiation of seminomatous from nonseminomatous testicular tumors, with excellent interobserver agreement.

Loss of FEV1 in cystic fibrosis: correlation with HRCT features

Abstract. The purpose of this study was to determine which high-resolution computed tomography (HRCT) features in patients with cystic fibrosis are most strongly associated with functional impairment as expressed by forced expiratory volume in one second (FEV1). Forty-seven patients with cystic fibrosis underwent chest HRCT and had pulmonary function tests. The HRCT examinations were evaluated for 11 features scored using a modification of Bhalla system and FEV1 was recorded as percentage of the predicted value. Univariate and multivariate correlations between HRCT scores and FEV1 were performed. The most common HRCT feature was bronchiectasis (98%) followed by atelectasis–consolidation (81%), bronchial wall thickening (77%), tree-in-bud sign (74%), mucous plugging (72%) and mosaic perfusion pattern (47%). On univariate analysis the following features correlated strongly with FEV1: bronchial wall thickening (p<0.0000001), tree-in-bud sign (p<0.0000001), mucous plugging (p<0.0000001), atelectasis–consolidation (p<0.0000001), thickening of interlobular septa (p<0.0002), severity (p<0.0002) and extent of bronchiectasis (p<0.0002). On multivariate analysis bronchial wall thickening and atelectasis–consolidation were the strongest independent determinants of the FEV1. We found a regression equation between FEV1 and the two HRCT features: FEV1=constant variable+a multiplied by bronchial wall thickening+b multiplied by atelectasis–consolidation (a and b=regression coefficients, R2=0.48). The major morphological determinants of functional abnormality in cystic fibrosis, as expressed by the loss of FEV1, are bronchial wall thickening and atelectasis–consolidation.

16-MDCT Cystoscopy in the Evaluation of Neoplasms of the Urinary Bladder

OBJECTIVE The purpose of this study was to evaluate the utility of 16-MDCT cystoscopy in the detection of urinary bladder neoplasms in a high-risk population. SUBJECTS AND METHODS Fifty patients who presented with hematuria and a recent diagnosis or a history of bladder carcinoma underwent CT cystoscopy. All patients were examined in the supine and prone positions after bladder distention with room air. A detector configuration of 16 x 0.75 mm and a pitch of 1.2 was used. Virtual images were obtained with volume-rendered algorithms. Transverse tomographic slices, multiplanar reformatted images, and virtual images were prospectively evaluated separately and in combination. Conventional cystoscopy was considered the standard of reference for assessing the efficacy of MDCT cystoscopy in the detection of urinary bladder tumors. RESULTS Fifty-five (96%) of 57 urinary bladder lesions recognized at conventional cystoscopy were detected with MDCT cystoscopy. The size of the lesions ranged from 0.3 to 9.7 cm in diameter, including 18 lesions with a diameter of 0.5 cm or less. Transverse, multiplanar reformatted, and virtual images proved complementary for lesion detection. CONCLUSION MDCT cystoscopy is an accurate technique for the detection of urinary bladder neoplasms in patients at high risk, yielding satisfactory results in the identification of lesions smaller than 0.5 cm.

Myxopapillary ependymoma of the conus medullaris with subarachnoid haemorrhage: MRI in two cases.

Abstract Subarachnoid haemorrhage due to cauda equina tumour is rare. We report two myxopapillary ependymomas of the conus terminalis, presenting with in this way. Rims of low signal were observed at their upper and lower borders, mainly on T2-weighted images. This finding has been described in ependymomas of the cervical region but not, to our knowledge, in myxopapillary ependymomas of the conus terminalis.

Pituitary gland height evaluated by MR in patients with β-thalassemia major: a marker of pituitary gland function

In transfusion-dependent β-thalassemia major, increased iron deposition in the pituitary gland has a cytotoxic effect leading mainly to hypogonadotropic hypogonadism. Our purpose was to assess in these patients the height of the pituitary gland and to evaluate whether it represents a marker of pituitary gland function. In 29 patients with β-thalassemia major and 35 age- and gender-matched controls the pituitary gland height was evaluated in a midline sagittal scan using a spin echo T1-weighted (500/20 TR/TE) sequence. In all patients, an extensive endocrine evaluation was performed, including measurements of spontaneous and stimulated levels of gonadotropins, thyroid hormones, growth hormone, insulin-like growth factor, and adrenal hormones. The pituitary gland height was lower in thalassemic patients with hypogonadotropic hypogonadism (n=15) (mean 3.48; SD 0.46) than in the age- and gender-matched controls (mean 6.29; SD 0.77), (P<0.001). No statistically significant difference was found between thalassemic patients without hormone dysfunction (n=14) (mean 5.34; SD 1.52) and age- and gender-matched controls (mean 5.91; SD 1.06). We conclude that in thalassemic patients the pituitary gland height is an additional marker of pituitary gland function and might be useful in clinical management.

Conventional MRI and magnetisation transfer imaging of tumour-like multiple sclerosis in a child.

Abstract. Tumefactive multiple sclerosis is a rare entity in children. Differential diagnosis includes other mass lesions such as neoplasm and abscess. A case of tumefactive multiple sclerosis in a child is presented. The open-ring pattern of enhancement on conventional MRI and magnetisation transfer imaging was important for the initial diagnosis and the evaluation of the course of the disease.

Acute spontaneous spinal subdural haematomas in a patient with essential thrombocythaemia

Sirs: Spinal subdural haematomas are rare, and most of them develop following trauma [11]. Spontaneous spinal subdural haematomas are far more uncommon and to our knowledge they have never been reported in patients with essential thrombocythaemia. Essential thrombocythaemia (ET) is a chronic proliferative disorder of the bone marrow that is characterized by increased production of platelets (PLT) [4]. In contrast to thrombocytopenia, a wellknown entity predisposing to spontaneous cranial subdural haematomas, thrombocythaemia manifests mainly with thrombotic events [1, 4]. There have been very few reported cases of spontaneous intracranial subdural haematomas complicating ET [2, 3, 9, 12] and only one case of spinal extradural haematoma [14]. We report a patient with known ET who presented with acute extensive spontaneous spinal subdural haematomas. A 60-year-old female with a history of E. T. was admitted with acute onset of severe headache, midscapular pain, and back pain radiating to both buttocks. No trauma was reported, not even a trivial one. Physical examination revealed neck stiffness, bilateral Lasegue sign and increased deeptendon reflexes in the lower limbs, but otherwise muscle power, sensory and bladder functions were intact. Plantar reflexes were flexor and her level of consciousness was normal. Her platelet count was 619.000, and the INR was 0.87. RBCs, WBCs, and biochemical tests were all within normal limits. A coagulopathy profile including activated protein C, protein S, antithrombine III, factor V, factor II, lupus anticoagulant, and anticardiolipine antibodies was normal. ANAs, anti-dsDNA, ANCA, RF, CRP, C3, C4, values were also negative/ normal. Examination of bone marrow smears disclosed a large number of giant megakaryocytes. Platelet aggregation studies were abnormal showing markedly reduced response to ADP, collagen, and epinephrine. After CT of the brain that did not reveal any abnormal findings, a lumbar puncture followed that produced an haemorrhagic CSF with xanthochromic supernatant after centrifugation. Eight days after the onset of symptoms MRI of the spine showed a longitudinal mass lesion within the ventrolateral subdural spinal space extending from T3 to L5 (Figs. 1 and 2). The lesion gave a heterogeneous high signal on both T1 and T2 weighted images suggesting subacute haemorrhage. Her past medical history was remarkable for two incidents of acute LETTER TO THE EDITORS

High resolution computed tomography of the chest in cystic fibrosis (CF): is simplification of scoring systems feasible?

The purpose of this study was to simplify HRCT scoring systems (SS) for CF by selecting representative HRCT parameters. Forty-two consecutive patients with CF underwent baseline and follow-up chest HRCT. Three radiologists evaluated 84 HRCTs employing five SS. “Simplified” HRCT SS were formed by selection of parameters exhibiting statistically significant relations with FEV1. Pulmonary function tests (PFTs) and nutrition (IBW%) were recorded. Regression analysis, Pearson correlation and T-test were used for statistical analysis. Three HRCT parameters were selected for the formation of “simplified” HRCT SS (severity of bronchiectasis, bronchial wall thickening, atelectasis-consolidation) using regression analysis. There was excellent correlation between each “simplified” and corresponding complete score (0.892 < r < 0.0967, p < 0.0001) or the remaining four complete scores (0.786 < r < 0.961, p < 0.0001). Strong correlation was found among the five “simplified” scores (0.803 < r < 0.997, p < 0.0001). Comparing baseline complete and “simplified” scores with corresponding follow-up ones, significant worsening was observed (p < 0.0001). PFTs and IBW% did not change significantly. HRCT scores correlated moderately with FVC and FEV1, but there was no correlation with FEF25-75 and IBW%. “Simplified” HRCT SS are as reliable as the complete ones and detect progression of lung disease earlier than clinical parameters. They are easy to use and could be adopted in clinical practice.