Field strength dependence of MRI contrast enhancement: phantom measurements and application to dynamic breast imaging.

Differences in MRI-measured contrast enhancement have been used for tissue characterization, particularly for the characterization of mammary tumours. T1 weighted spoiled gradient echo sequences have usually been acquired for this purpose and relative signal intensity increase (Srel) has been determined to quantify contrast uptake. The field strength dependence of this technique is evaluated in this paper by phantom measurements. Srel is compared with the recently introduced "enhancement factor" (EF) and "contrast uptake equivalent" (CE) as a quantitative assessment parameter for contrast uptake. Enhancing tissues were simulated with water phantoms doped with increasing concentrations of Gd-DTPA. Spoiled gradients echo images (FLASH-2D) were obtained on a 0.2 T and 1.5 T MR system. Srel, EF and CE were determined and the results of the phantom measurements were applied to typical types of breast tissues. Srel showed a strong dependence on the magnetic field strength and was greater at higher field strengths. This is because Srel correlates positively with the native T1 which is longer at higher field strengths. Conversely, the EF and CE almost eliminated the distorting influences of the magnetic field strength. CE provided a good approximation of the actual contrast uptake. In practice, the dependence of Srel on the magnetic field strength might cause malignant lesions to be misclassified as benign at low field strengths. Either Srel criteria should be adjusted to magnetic field strength or EF and CE should be used instead of Srel for tissue characterization with dynamic contrast-enhanced MRI.

Endoscopic ultrasonography versus computed tomography in the differential diagnosis of perianorectal complications in Crohn's disease.

In this prospective study the performance of transrectal or transvaginal endoscopic ultrasonography (EUS) was compared with that of computed tomography (CT) in the diagnosis of perirectal fistulae, abscesses and diffuse inflammatory changes in the lower pelvis in 25 patients with Crohn's disease. Results were verified by surgery in eight patients and by correlation with findings on endoscopy, barium radiography and fistulography, and the clinical course in all other patients. EUS was superior to CT in diagnosing fistulae (14 vs 4 correct diagnoses) and inflammatory infiltration of the lower pelvic muscles (11 vs 2 correct diagnoses). The methods were equivalent in diagnosing perianorectal abscesses. CT was superior in the detection of inflammatory changes in the pararectal fasciae and fatty tissue which could not be detected by EUS. It is concluded that EUS should be used as the primary method for diagnosing perianorectal changes in patients with Crohn's disease especially in the case of fistulae and abscesses, having the added advantage of lack of radiation for the patient.

Polymyositis: MRI-appearance at 1.5 T and correlation to clinical findings.

The thigh regions of 10 patients suffering from polymyositis were examined by magnetic resonance imaging (MRI) at 1.5 T; follow-up examinations were performed in all patients. MRI findings were correlated with findings at physical examination and serological parameters. In four patients focal areas of hyperintensity on T2-weighted (T2W) spin echo (SE) images were found within muscles. They were not detectable on T1-weighted (T1W) images. In three of these cases enhancement within the musculature was seen following i.v. administration of Gd-DTPA on T1W images. In another five patients there was varied replacement of muscle by fatty tissue. In one patient the muscle appeared completely normal. On follow-up three patients showed definite changes in imaging findings; two correlated well with clinical and biochemical findings while the third exhibited massive deterioration clinically with mild improvement on imaging. Seven patients exhibited no change on MRI; four of these had shown a significant clinical change in the course of the disease, whilst three were clinically stable. In our small series MRI using SE technique (T1W and T2W) and contrast enhancement to date seems to be of limited value for the assessment of muscular changes during therapy. The i.v. use of Gd-DTPA did not add to MRI's diagnostic value in this series.

[The percutaneous aspiration and drainage of infected fluid retention after organ transplantation]. / Perkutane Aspiration und Drainage infizierter Flüssigkeitsretentionen nach Organtransplantation.

Local postoperative infections in immunosuppressed patients carry a high mortality rate. In this group of patients interventional radiological procedures are particularly valuable in diagnosis and treatment. We report on the results of radiologically controlled aspirations (11 cases) and drainage (37 cases) of infected fluid collections in 47 patients following transplantation of various organs. By percutaneous aspiration or drainage, 91.7% of infected fluid collections were successfully treated or the clinical condition of the patient improved so that surgical intervention could be avoided. The causative organism was identified and antibiotic treatment carried out in 72.9% (35 cases). Surgical intervention was necessary in only 4.3% (2/48). Needle aspiration or drainage of percutaneously accessible fluid collections thought to be infected appears to be particularly useful for transplant patients at increased risk and is a good alternative to surgical treatment.

CT and MR accuracy in the detection of tumor recurrence in patients treated for ovarian cancer.

OBJECTIVE: The aim of this prospective study was to evaluate the accuracy of clinical examinations (palpation/determination of serum tumor-associated antigen CA125 level), CT, and MRI in the detection of tumor recurrence in patients with treated ovarian cancer. MATERIALS AND METHODS: Twenty-four patients who had been treated for ovarian carcinoma were prospectively examined by clinical means (palpation/serum tumor-associated antigen CA125 level), CT, and MRI to assess their accuracy in detecting recurrent disease; results were correlated with surgical/bioptic/pathoanatomic findings. Nine patients had relapse; 15 women were disease-free. RESULTS: Examinations were true-negative in 14 patients (on palpation/CA125, CT, and MRI) and true-positive in 9 on palpation/CA125, in 6 on CT, and in 7 patients on MRI. False-positive examinations occurred in one patient on palpation/CA125, CT, and MRI and false-negative in zero on palpation/CA125, in three on CT, and in two on MRI, a sensitivity of 100% for palpation/CA125, 66.6% for CT, and 77.7% for MRI and a specificity of 93.3% for palpation/CA125, CT, and MRI. Accuracy of palpation/CA125 examinations was 95.8% in comparison with 83.3% for CT and 87.5% for MRI. CONCLUSION: Our results suggest that in the follow-up of ovarian cancer patients, assessment of serum tumor-associated antigen CA125 level is accurate in the determination of patients with tumor recurrence. Computed tomography is the primary imaging modality to prove macroscopic disease recurrence and can spare these patients from invasive restaging second-look laparotomy; MRI should be performed in women with questionable macroscopic recurrent tumor and negative CT examination. Neither CT nor MRI can confidently exclude microscopic disease.

High-resolution computed tomography of the lungs in irradiated breast cancer patients.

Fifty-five breast cancer patients underwent high-resolution computed tomography (HRCT) of the lungs before, 8-12 weeks, 6, 9 and 12 months after adjuvant radiotherapy. During the follow-up time, 17 of them (30%) were found to develop minimal parenchymal alterations in the irradiated lung volume by HRCT evidence. The parenchymal alterations were classified by five scores. Scores 1-4 described chronic radiologic changes, score 5 acute radiologic changes. Three patients presented with acute radiologic changes (alveolar filling) within the first 3 months after radiotherapy. Two did not show any abnormalities at later follow-ups. Chronic radiologic fibrosis (15 patients) was not seen before the sixth month post irradiation except in 2 cases. There was no correlation between acute changes and chronic fibrosis. None of these changes were seen at a lung dose of less than 40 Gy. The appearance of interstitial pulmonary lesions secondary to breast irradiation was comparable to that of other interstitial diseases of the lungs. Chest radiographs were normal in all patients. None of the 55 patients presented with clinical symptoms.

[High-resolution computed tomography of the lung in young patients with cystic fibrosis]. / Hochauflösende Computertomographie der Lunge bei jungen Patienten mit zystischer Fibrose.

In a prospective study we proved the value of high-resolution computed tomography (HRCT) and the CT scoring system developed by Stiglbauer et al. on 47 young patients suffering from cystic fibrosis (CF) (median age: 10.1 years). The most frequent pulmonary finding was bronchial wall thickening (BWT) in 43 patients (94.6%), followed by bronchiectasis (BE) in 36 patients (79.2%). A less frequent finding was ill-defined patchy consolidation (39.6%). We found an almost even distribution of BWT and BE in the upper and lower lobes of the lung. These two findings were scored according to their severity and extent. The maximum possible score for BWT and BE was 72 in a single patient. For both the overall score was 19.9 +/- 11.1. A statistically significant correlation of the CT scoring system with the lung function tests FEV1/FVC (P = 0.03) and MEF50 (P = 0.02) was found. The results of HRCT and the CT scoring system were shown to be valuable methods in the assessment of pulmonary changes, in young patients suffering from CF.

[High-resolution computed tomography (HR-CT) of the lung following lung transplantation]. / Hochauflösende Computertomographie (HR-CT) der Lunge nach Lungentransplantation.

We report our high-resolution computed tomography (HRCT) and conventional CT findings after lung transplantation in 20 patients. Sixty-four examinations were performed 7-511 days after transplantation. The radiological observations were then correlated with the clinical results. The pathological findings in the early postoperative phase were pleural effusion, edema, and pulmonary consolidation. The HRCT findings associated with acute rejection were nonspecific. Dilation and thickening of the walls of the peripheral bronchi is a common, but non-specific feature in bronchiolitis obliterans. The manifestations of posttransplant lymphoproliferative disorder are discussed in two patients.

[Stenosis of the extracranial carotid artery]. / Stenose der extrakraniellen Arteria carotis.

Magnetic resonance angiography (MRA) as well as intraarterial digital subtraction angiography (DSA) were performed in 45 patients suffering from cerebrovascular disease, both procedures within one week of each other. MRA und DSA were evaluated separately for every patient retrospectively by two experienced radiologists on consensus basis. The results were then compared using catheter angiography as gold standard. Evaluation was confined to the common and internal carotid arteries (CCA, ICA) in the neck subdivided into 5 grades of stenosis. A comparative assessment was impossible in 9% cases due to motion artifacts and patient malposition. Out of 18 verified CCA stenoses 13 were demonstrated by MRA and 39 out of 44 ICA stenoses were assessed by MRA. There was a highly significant correlation between degree of stenosis detected by the two methods. Spearman Rank correlation coefficients of 0.824 and 0.913 were found for CCA and ICA, respectively.

Sonography of nonneoplastic disorders of the salivary glands.

We examined 637 patients with salivary gland disorders by real-time sonography. In 270 patients, the possibility of neoplasia of the salivary glands could not be excluded by ultrasound. In the remaining 367 patients, the following disorders were diagnosed sonographically: acute inflammation (72 patients), Sjögren's syndrome or chronic inflammation (81 patients), abscess (9 patients), sialolithiasis (192 patients), and cysts (13 patients). The present study discusses the ultrasound appearances of a variety of diseases and the indications and limits of sonography in the evaluation of salivary gland pathology.

Color Doppler imaging of inferior vena cava: identification of tumor thrombus.

Color-coded Doppler sonography (CCDS) was used for the examination of tumor thrombus (n = 7) and benign thrombosis (n = 6) of the inferior vena cava. Tumor thrombus was due to hepatocellular carcinoma in two cases and to renal cell carcinoma in five cases. Whereas no specific information about the nature of thrombus formation could be gained by gray scale sonography, a typical patchy vascularization pattern was noted within tumor thrombi in six of seven cases using CCDS. This ws due to marked neovascularization within the tumor thrombi, confirmed by histologic examination in all cases. In one patient no vascularization within the tumor thrombus could be observed by CCDS because the thrombus was relatively small. In patients with bland thrombosis, either no vascularization of the thrombus was seen (n = 5) or linear recanalization of the thrombus occurred (n = 1). Therefore, it might be possible to differentiate tumor from nontumor thrombus in the inferior vena cava by using CCDS. Further studies are needed to confirm this preliminary hypothesis.

High resolution CT in children with cystic fibrosis.

High resolution CT (HRCT) was performed in 24 children (median age 57.9 months) suffering from cystic fibrosis (CF). In 23 patients (one examination unacceptable because of motion artifacts) the most frequent finding was bronchial wall thickening, shown in 21 patients (91%), followed by bronchiectasis in 15 patients (65%). Less frequent findings were mucus plugging and patchy consolidations, which could be demonstrated in 11 patients each (48%). Findings were classified using a CT scoring system and including only irreversible pulmonary changes; a statistically significant correlation with lung function tests (FEV1/FVC; MEF50) could be established. HRCT to date seems to be the most valuable method to determine extent and severity of lung involvement in children with CF and should therefore be routinely used for the staging of this disease.

[The technic of adrenal biopsy. Ultrasound versus CT as the guidance method]. / Technik der Nebennierenbiopsie. Ultraschall versus CT als Zielmethode.

Forty-seven needle biopsies of the adrenal glands have been performed under ultrasound or CT guidance. The aim was to clarify the best guidance method, the best approach, the choice of biopsy needle and possible complications. Analysis of the results provided the following answers: 1. A mass in the right adrenal can be biopsied under ultrasound control by a transhepatic approach. Small lesions of the left adrenal are best approached under CT guidance. In these cases a subcostal angled approach is advised. 2. Cutting biopsy needles provide better results than aspiration biopsy needles. 3. The complication rate of adrenal biopsies is very low if thin cutting needles are used.

[High-resolution computed tomography (HR-CT) of the lung before transplantation. The value of methods for evaluating the recipient]. / Hochauflösende Computertomographie (HR-CT) der Lunge vor Transplantation. Wertigkeit der Methode zur Empfängerevaluation.

We examined the lungs of 49 patients with end-stage lung disease non-responding to conventional therapy when referred to lung transplantation by means of high resolution computed tomography (HR-CT). In 24 of these patients lung transplantation has been performed meanwhile. All scans were evaluated separately for both lungs with special regard to presence and extend to the following findings, in order to select the adequate type of transplantation procedure: pleural thickening, bullae and bronchiectasis. In patients with end-stage emphysema the severity of parenchymal damage was recorded additionally. In 20 patients (40.8%) HR-CT results had a major impact on the selection of the surgical procedure. In 16 cases single lung transplantation was recommended because parenchymal changes were either localised unilaterally or a significant difference regarding the severity of emphysematous changes from one side to the other. In 4 cases double lung transplantation was the adequate procedure due to bilateral bronchiectasis or bullae. Based upon these results HR-CT seems indispensable in patients prior to lung transplantation.

Case report: lipoma of the liver--ultrasound, CT and MR imaging.

A case of lipoma of the liver is presented; ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) findings are reviewed and compared with previous reports. The ultrasound pattern and appearance of the tumour in CT as well as MRI are discussed.

[The value of thoracic and abdominal computed tomography with intensive care patients]. / Wertigkeit der thorakalen und abdominellen Computertomographie bei Intensivpatienten.

We evaluated in a retrospective study the therapeutic relevance of thoracic and abdominal CT examinations on 157 intensive-care patients with previously inconclusive radiological examinations. Indications for CT were sepsis (n = 105), rarely a decrease in haematocrit (n = 30), multiorgan failure (n = 16) or suspected aortic aneurysm (n = 6). In 83.4% of examinations CT detected clinically relevant features, in 44.3% positive CT studies resulted in invasive therapy within 72 hours and therefore changed patient management decisively. Our results justify the use of CT, enabling if necessary an on-target intervention, the advantages outweighing the inherent risks if the patient is exposed to the relatively small risk of being temporarily removed from the intensive-care unit for immediate invasive treatment.

MRI in the diagnosis of primary lymphoma of bone: correlation with histopathology.

Seven patients with primary non-Hodgkin lymphoma of the skeleton were examined with MRI. The results were compared to "small cell" primary malignant bone tumors. The latter showed marked hyperintensity on SE T2-weighted images; in contrast, the lymphomas appeared as inhomogeneous lesions of low signal intensity on T2-weighted images. Histologic examination with silver stains of specimens of these lesions revealed a high content of fibrous tissue, which could explain the signal behavior on MR. All seven lymphomas were located in the epiphysis or metaphysis of the appendicular skeleton; intraarticular tumor growth was demonstrated in five cases.

[Results after conservatively managed vertebral fractures of the thoracolumbar level with special reference to bony stenosis of the spinal canal]. / Ergebnisse nach konservativ versorgten Wirbelfrakturen am thorakolumbalen Ubergang unter besonderer Berücksichtigung knöcherner Stenosen des Spinalkanals.

Seventy-two patients with compression fractures of the lower thoracic and lumbar spine who were treated by the Böhler method from 1972 to 1987 were followed up to compare the clinical signs and the results of conventional radiography and spinal computed tomography. There were 33 men and 39 women with an average age of 44.3 years (23-69 years). Treatment by the Böhler method is indicated for fractures between T12 and L5, which constitute 60% of all vertebral fractures. The main distribution in our patients was T12 (n = 26) and L1 (n = 33). Four patients primarily had neurological symptoms. The mean duration of hospitalization was 16 days (4-54). In our results, back pain is the most frequent complaint. A comparison with the findings on the day of the accident showed that the vertebral deformity decreased in all cases (index: mean accident = 0.64; mean follow-up = 0.82). In the CT scan we found spinal stenosis in up to 30% in 9 patients (12.5%) with no neurological symptoms. Based on these results, the authors recommend the Böhler method in lower thoracic and lumbar compression fractures without neurological symptoms. The main aim of the treatment must be reduction of the vertebral deformity to a minimum in order to maximize the biomechanical integrity of the vertebral column and prevent degenerative changes. The use of computed tomography is recommended even in these fractures because of possible spinal stenosis. CT is accurate, especially in evaluating the nature of facet joint failure.

CT in pancreatic involvement of non-Hodgkin lymphoma.

In an attempt to evaluate characteristic CT features of primary pancreatic involvement in non-Hodgkin lymphoma (NHL), scans of 10 patients were reviewed retrospectively and compared to 50 patients with histologically proved different neoplasms of the pancreas. Setting the correct diagnosis of NHL would be essential for planning of treatment and prognosis. CT findings of NHL were characteristic but not specific. Nevertheless, the presence of a homogeneous pancreatic mass with a diameter of 7 cm or more, infiltrating surrounding tissue accompanied by retroperitoneal and/or mesenteric lymphadenopathy strongly suggests NHL. CT-guided needle biopsy can help to establish the diagnosis of pancreatic NHL.