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Biomedical subjects

J Hierholzer

Publications and source records attributed to J Hierholzer.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Role of flowmetric analysis and of color-Doppler ultrasonography with contrast media in the different phases and follow-up of Graves' disease].

PURPOSE: The objectives of this study were: 1) to evaluate the role of color-Doppler ultrasonography (CDU) assessment of thyroid vascularity, measuring the peak systolic velocity (PSV) at the level of the inferior thyroid artery, and the intrathyroid vascularization in Graves' diseas; 2) to evaluate the role of contrast agent administration in predicting the relapse of hyperthyroidism or the biological activity of the disease after withdrawal of antithyroid drugs. PATIENTS AND METHOD: The study included 74 Graves' patients (59 F/ 15 M; mean age 45 years; range 23-71). Graves' disease was diagnosed according to the usual clinical and laboratory criteria. On the basis of the clinical and biochemical findings we divided Graves' patients into 4 different groups. Treatment was continued for at least 12 months, CDU examination was carried out after discontinuing therapy. Eight patients showed a relapse of hyperthyroidism within 5 months after suspension of therapy. In all cases the evaluation of intraparenchymal vascularization and PSV at the level of the inferior thyroid artery in basal conditions was followed by administration of contrast agent (Levovist, 300 mg/ml), with slow infusion (<2 ml/min) to avoid blooming artifact. Intraparenchymal vascularization was classified into 4 patterns according to Vitti et al. RESULTS: The value of the peak systolic velocity (PSV) at the level of the inferior thyroid artery was the best predictor of relapse. A value higher than 40 cm/sec was present in all the patients that showed relapse and only in two patients with stable remission. Administration of contrast agent is important to evaluate the biological activity of the disease. In the 5 patients exhibiting slightly increased vascularization after contrast agent administration we could assume the clinico-pathological recovery. CONCLUSIONS: CDU study of thyroid vascularization, based on the measurement of PSV at the level of the inferior thyroid artery and on the response to contrast agent administration is useful to distinguish three groups of patients: A) PSV >40 cm/sec with pattern III for at least 10 minutes from the beginning of the contrast agent administration (High risk of relapse); B) PSV <40 cm/sec with pattern II or III after contrast agent administration (Biological activity of the disease-Thyroiditis); C) PSV <40 cm/sec with Pattern I after contrast agent administration (Poor biological activity of the disease-recovery).

Adult↗
PubMed2001

Magnetic resonance imaging in distinguishing malignant from benign pleural disease.

OBJECTIVE: To explore the role of magnetic resonance imaging (MRI) in distinguishing malignant from benign pleural disease. METHODS: All 64 patients were examined with both computed tomography (CT) and MRI. The morphologic features of pleural lesions and MR signal intensity on T1-weighted, T2-weighted and contrast-enhanced T1-weighted images were evaluated. RESULTS: Mediastinal pleural involvement, circumferential pleural thickening, nodularity, irregularity of pleural contour, and infiltration of the chest wall and/or diaphragm were most suggestive of a malignant cause on CT and MR images. Contrary to what has been reported in the literature, pleural thickness greater than 1 cm either on CT or on MRI did not reveal a significant difference between malignant and benign pleural disease (P > 0.05, chi-square test). Using morphologic features in combination with signal intensity features, MRI had a sensitivity of 98% and a specificity of 92% in the detection of pleural malignancy. CONCLUSIONS: Compared with those on CT, the morphologic features on MRI allowed a mostly equal and in some cases superior detection and evaluation of the spread of pleural disease. In combination with signal intensity and morphologic features, MRI is very useful in distinguishing malignant from benign pleural disease.

Adult↗
PubMed2000

MRI in decompression illness.

We report a case of decompression illness in which the patient developed paraparesis during scuba diving after rapid ascent. MRI of the spine revealed a focal intramedullary lesion consistent with the symptoms. The pathophysiological and radiological aspects of spinal decompression illness are discussed.

Adult↗
PubMed2000

MRI and CT in the differential diagnosis of pleural disease.

STUDY OBJECTIVE: To explore the role of MRI in the differential diagnosis of pleural disease. PATIENTS: Forty-two patients with pleural disease were included. METHOD: Retrospective study. All patients were examined with both CT and MRI. The morphologic features of pleural lesions and magnetic resonance signal intensity on T1-weighted, T2-weighted, and contrast-enhanced T1-weighted images were evaluated. RESULTS: Mediastinal pleural involvement, circumferential pleural thickening, nodularity, irregularity of pleural contour, and infiltration of the chest wall and/or diaphragm were most suggestive of a malignant cause both on CT and MRI. Pleural calcification on CT was suggestive of a benign cause. Contrary to what has been previously reported in the literature, neither on CT nor on MRI, pleural thickness >1 cm revealed significant difference between malignant and benign pleural disease (p>0.05, chi(2) test). High signal intensity in relation to intercostal muscles on T2-weighted and/or contrast-enhanced T1-weighted images was significantly suggestive for a malignant disease. Using morphologic features in combination with the signal intensity features, MRI had a sensitivity of 100% and a specificity of 93% in the detection of pleural malignancy. CONCLUSION: When signal intensity and morphologic features are assessed, MRI is more useful and therefore superior to CT in differentiation of malignant from benign pleural disease.

Adult↗
PubMed1999

Contribution of color and power Doppler sonography to the differential diagnosis of acute and chronic rejection, and tacrolimus nephrotoxicity in renal allografts.

The aim of the present study was to differentiate acute rejection, chronic rejection, and tacrolimus nephrotoxicity with color and power Doppler imaging of renal transplants. One hundred examinations were obtained from 45 patients. Pulsatility and resistive indices were calculated from color Doppler images. The grade of renal vascularization was quantified using computer-assisted pixel analysis in a rectangular region-of-interest. The percentage of vessel-covered renal parenchyma (POV) was calculated using a histogram that discriminated renal vessels from renal parenchyma via power Doppler images. Furthermore, the distance from the most peripherally located vessels to the renal capsule (PVD) was measured. A reduced POV < or = 55% proved to be the best discriminator when chronic rejection was suspected (sensitivity 79%, specificity 87%). Tacrolimus nephrotoxicity showed not only a moderate elevation of the Doppler signal but also an increased PVD > or = 3.9 mm and a normal POV. We conclude that the evaluation of renal vessels by power Doppler images improves diagnostic accuracy for patients with renal allografts.

Acute Disease↗
PubMed1999

[Malignant lymphoma: magnetic resonance tomography findings in residual supradiaphragmatic space-occupying lesions].

PURPOSE: Evaluation of MR imaging in patients with Hodgkin's lymphoma and high grade non-Hodgkin's-lymphoma and mediastinal residual mass after first line chemotherapy. MATERIALS AND METHODS: MR imaging (1.5 T) was performed in 36 patients (Hodgkin's lymphoma n = 26, NHL n = 10) after first line chemotherapy). Twenty patients had inactive residual mass, 16 patients had residual lymphoproliferative lesions. T1- and T2-weighted spin echo images were visually analysed by a score index (range 1-5) as well as quantification of enhancement by signal-intensity-ratios SImax/SIplain). RESULTS: For the differentiation between residual lymphoproliferative activity and inactive residual mass, the highest accuracy was obtained for the signal intensity of residual mass on T2-w-SE compared to pectoralis muscle (94% sensitivity, 80% specificity, likelihood ratios: 4.0 [LR+]; 0.3 [LR-]). The cut-off value of the SI ratio was calculated retrospectively at 1.96 (p > 0.05). CONCLUSIONS: Differentiation between inactive (fibrotic) and lymphoproliferative (active) residual mediastinal mass is possible by MR imaging using as parameter the size reduction after therapy and the signal intensity on T2-w-SE in comparison to pectoralis muscle. Thus study suggests an additional value using the SI ratio for the differentiation.

Adult↗
PubMed1998

Imaging in epidural lipomatosis.

This paper reviews the literature concerning symptomatic epidural lipomatosis. The different diagnostic procedures (conventional myelography, computed tomography, and magnetic resonance imaging) and therapeutic approaches (including medical treatment, surgery, and dietary influence) are discussed.

Journal Article↗
PubMed1998

Morphological changes in chest radiographs of patients with acute respiratory distress syndrome (ARDS).

OBJECTIVE: To determine whether the quality of infiltrations in chest radiographs can accurately predict the histological extent of fibrotic change in patients with acute respiratory distress syndrome (ARDS). DESIGN: Retrospective clinical investigation. SETTING: Intensive care unit (ICU) of a university teaching hospital. PATIENTS AND METHODS: Of 47 patients treated with extracorporeal membrane oxygenation (ECMO) for severe ARDS over a 5-year period, 23 patients underwent open lung biopsy at thoracotomy for treatment, mostly of pneumothorax. Chest films obtained by portable chest roentgenography preceding the operation were reviewed retrospectively and compared to the histomorphological results of the lung specimen. RESULTS: Chest radiographs displayed mixed alveolar-reticular opacification in 60.2%, alveolar patterns in 22.9% and reticular opacities in 10.5%. In 0.4% there were no infiltrates, 6% could not be evaluated because of insufficient quality. There was no relevant difference between the right and left lungs. Subdividing patients into two groups according to the histological results of either absent or mild (1) or severe (2) lung fibrosis, we found an alveolar haziness in 12.3% in group 1 compared with 28.2% in group 2, while reticular characteristics were identified in 13% and 11%, respectively. CONCLUSIONS: The most common opacity in chest radiographs of patients with severe ARDS treated with ECMO is mixed alveolar-reticular opacification. Severe lung fibrosis is not positively correlated with a reticular radiographic pattern. ECMO does not lead to specific radiological changes in conventional radiograms, contrary to clinical findings that treatment with ECMO might induce pleural or pulmonic haemorrhage, especially in the earlier days when systemic heparinization had to be used instead of the heparin-coated tube-surfacing.

Adolescent↗
PubMed1998

Quantitative estimation of I-123-Iomazenil receptor binding in temporal lobe epilepsies using two SPECT acquisitions--comparison with the regional cerebral blood flow and a compartment model.

AIM: To compare published fractional rate constants of I-123-Iomazenil (IMZ) and C-11-Flumazenil (three-compartment/four-parameter model) with a I-123-Iomazenil receptor index calculated from two SPECT acquisitions and to compare the receptor index of the epileptogenic area with the contralateral side in patients with unilateral temporal lobe epilepsies. METHODS: 28 patients were studied. 13/28 patients had a drug-resistant unilateral temporal lobe epilepsy with a successful focus localisation performed by an extensive video/EEG monitoring. 15 other patients with clinically suspected focal epilepsy and a normal MRI and IMZ SPECT scanning were used as controls. SPECT scanning was performed in all patients 15 and 100 min after intravenous injection of 111 MBq IMZ and 10 min after application of 740 MBq Tc-99m-HMPAO. Quantification of the regional uptake was performed using ROI-technique and the specific and non-specific binding of IMZ was calculated. The receptor index was calculated by the difference of the specific binding from 15 to 100 min p.i. divided by the time interval. RESULTS: The receptor index showed a linear correlation with recently published fractional rate constants k3 (r = 0.69 and 0.67; p = 0.15) and a moderate correlation with the k4 constant (-0.53 and -0.43; p = 0.28) by the means of C-11-Flumazenil PET and I-123-Iomazenil SPECT studies, respectively. However, statistical significance was not reached due to the few data points available from the published reports. Furthermore, the IMZ receptor index was lower in the epileptogenic area of patients with unilateral temporal lobe epilepsies compared with their contralateral side (p = 0.02; Wilcoxon-test). The IMZ receptor index showed a weak correlation with the regional cerebral blood flow independent of the evaluated region (r < 0.4; p < 0.05). CONCLUSION: The IMZ receptor index indicated to be a simple routine approach to estimate the fractional rate constant k3 (r = 0.67). The lower value of the receptor index within the epileptogenic area might be due to a lower receptor density. However in further studies, IMZ might be a helpful tool to find out subtle changes of the receptor affinity due to its approximately 30-fold higher ligand-receptor affinity compared to C-11-Flumazenil.

Adult↗
PubMed1998

Loss of dopamine-D2 receptor binding sites in Parkinsonian plus syndromes.

UNLABELLED: This study analyzed temporal changes of striatal dopamine-D2 receptor binding during the course of different extrapyramidal movement disorders using 123I-iodobenzamide (IBZM) SPECT. METHODS: Eighteen patients (9 with Parkinson's disease, 9 with parkinsonian plus syndrome) were followed for 11-53 mo. Dopamine-D2 receptor binding was assessed using 123I-IBZM SPECT at the beginning and at the end of the follow-up period. SPECT data were acquired 120 min postinjection of 3-5 mCi 123I-IBZM. A semiautomated algorithm was applied to the raw data for semiquantitative evaluation of regional cerebral receptor binding. RESULTS: Intraobserver (r = 0.992) and interobserver (r = 0.930) variance was low for the semiautomated interpretation of the SPECT examination of the dopaminergic D2 receptor binding, reflecting a highly reproducible SPECT algorithm. Mean specific dopamine-D2 receptor binding was lower in patients with parkinsonian plus syndrome compared to patients with Parkinson's disease on the initial (p < 0.001) as well as the follow-up study (p < 0.001). In patients with Parkinson's disease, we observed an unaffected receptor binding compared to a reduced binding of radiotracer in patients with parkinsonian plus syndrome during the course of the disease (p < 0.001). CONCLUSION: During the follow-up, patients with Parkinson's disease showed a constant dopamine-D2 receptor binding. In contrast, patients with parkinsonian plus syndrome revealed a decline of the binding of dopamine-D2 receptor. These findings are in agreement with histopathological data that demonstrated a preserved dopamine-D2 receptor status in patients with Parkinson's disease and a decline of the dopamine-D2 receptors in patients with parkinsonian plus syndrome. SPECT examinations using 123I-IBZM are useful for assessing dynamic changes of dopamine-D2 receptors in extrapyramidal movement disorders. Semiquantitative SPECT evaluations may provide valuable information for clinical management and prognosis of the patient with extrapyramidal movement disorders.

Adult↗
PubMed1998

[Imaging tumor extension of renal cell carcinomas with magnetic resonance tomography. Improved tumor-tissue contrast with Gd-DTPA-assisted spin-echo sequences and simultaneous fat suppression].

PURPOSE: To evaluate the use of contrast-enhanced T1-weighted images with fat suppression (T1FS) to improve the contrast-to-noise ratio of renal cancer and renal parenchyma as well as perirenal fat. METHODS: 25 patients with histologically proven unilateral renal cancer after nephrectomy were examined before surgery. In addition to plane and contrast-enhanced T1-weighted as well as T2-weighted spin-echo images, all patients had T1 FS immediately after administration of Gd-DTPA in two planes. The contrast-to-noise ratio was calculated using circular regions-of-interest which outlined the tumor, the renal parenchyma, pyelon, and the perirenal fat. RESULTS: T1 FS significantly improved the contrast-to-noise ratio of renal cancer and renal parenchyma compared to all conventional spinecho sequences (p < 0.001; Wilcoxon-Test). Compared to contrast-enhanced T1-weighted images without fat-suppression T1 FS yielded a higher CNR of the tumor, the perirenal fat and the pyelon. Another advantage was the absence of the chemical-shift artifact which is mostly pronounced in T2-weighted images and a reduced number of observed artifacts due to breathing. CONCLUSION: T1 FS should replace conventional contrast-enhanced T1-weighted spin-echo images in the work-up of renal cancer using MRI.

Adult↗
PubMed1998

[The assessment of skin tumors with magnetic resonance with high resolution and a paramagnetic contrast medium].

INTRODUCTION: The technologic improvement of surface coils in MRI has allowed better visualization of the skin and thus permitted the clinical use of this technique in dermatology. MRI allows to assess the depth and extent of skin tumors and to detect any malignant transformation. The MR differentiation between benign and malignant skin lesions relies on morphological criteria which however do not have an absolute diagnostic value. We investigated the role of paramagnetic contrast agents in the differentiation between benign and malignant skin lesions. MATERIAL AND METHODS: Forty-one patients, 33 with benign and 8 with malignant skin tumors, were submitted to MRI. All the examinations were performed with a 1.5 T superconductive unit, with a 2.5 cm surface coil. Axial T1- and T2-weighted SE images were acquired with 2 mm slice thickness. Paramagnetic contrast material was administered to all patients. The signal intensity of the skin lesions was calculated before and after paramagnetic contrast agent administration positioning a region of interest. A percentage ratio of contrast enhancement was calculated to quantify contrast agent uptake and the relative values were compared between benign and malignant lesions. A qualitative analysis was also performed rating the contrast enhancement of each lesion as high, intermediate, or absent. RESULTS: The quantitative analysis showed a statistically significant difference (p < .5) between the contrast enhancement values of benign and malignant lesions. In particular, malignancies had values ranging 117.3 (+/- 28.7) to 125 (+/- 32.4), while benign lesions had -20.6 to 99.8 (+/- 21.1). Conversely, no difference in contrast enhancement was found at qualitative analysis. CONCLUSIONS: MRI is a promising tool for characterizing skin tumors. Our preliminary results should be confirmed on larger series of patients with the use of high temporal resolution imaging sequences.

Adolescent↗