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Purpose: To document the value of fast contrast enhanced-sequences in the assessment of the vascular supply and parenchymal perfusion in renal transplants., Patients: 18 recipients of a renal transplant were examined with a 1.5-tesla-MR-system. The protocol included fast contrast enhanced 3D MR angiography and coronal 2D GRE sequences. The transplant artery and vein were assessed as well as regional parenchymal perfusion., Results: 3D MRA detected three transplant artery stenoses and one occlusion. In addition, two renal vein thromboses and one compression were identified. Perfusion deficits were documented in 8 renal transplants: renal infarction (n = 4), cortical necrosis (n = 2), acute tubular necrosis (n = 1) and venous ischemia (n = 1). Fluid collections were documented as well as dilation of the collecting system and abnormalities of the surrounding tissues., Conclusion: Contrast enhanced MRI and MRA permit a comprehensive assessment of renal transplants without inducing nephrotoxicity.

Purpose: "Exoscopic" and endoscopic identification of colorectal pathologies via MRI., Methods: 5 patients (36-88 years), two normal and three with different colorectal pathologies (diverticular disease, polyps and carcinoma of the colon), were examined by MRI after colonoscopy. Subsequent to filling of the colon with a gadolinium-water mixture under MRI-monitoring, 3D-data sets of the colon were acquired in prone and supine positions over a 28 sec breath hold interval. Subsequently multiplanar T1-weighted 2D-sequences were acquired before and following i. v. administration of Gd-DTPA (0.1 mmol/kg BW). All imaging was performed in the coronal orientation. The 3D-data were interactively analysed based on various displays: maximum intensity projection (MIP), surface shadowed display (SSD), multiplanar reconstruction (MPR), virtual colonoscopy (VC)., Results: All of the colorectal pathologies could be interactively diagnosed by MPR. On MIP images some pathologies were missed. VC presented the morphology of colon haustra as well as of all endoluminally growing lesions in a manner similar to endoscopy. The colon masses showed uptake of contrast media and could thus be differentiated from air or faeces., Conclusion: The potential of CMRI in colorectal diagnosis warrants further investigation in a larger series of patients.

Purpose: To establish the value of computed tomography (CT) and magnetic resonance imaging (MRI) in predicting bladder and rectum involvement in uterine carcinoma., Material and Methods: 6 different imaging signs (focal obliteration of perivesical or perirectal fat planes, area and angle of contact between uterus and bladder or rectum, asymmetric bladder or rectum wall thickening, evidence of intraluminal masses, and signal intensity of bladder or rectum wall on T2-weighted or contrast-enhanced MR images) were analysed retrospectively in 129 patients who underwent 92 CT and/or 64 MRI examinations. The data were correlated with intraoperative findings and the results of cystoscopy and rectoscopy., Results: Asymmetric wall thickening, evidence of intraluminal masses and increased signal intensities of the bladder wall or rectum wall were valuable signs of infiltration (sensitivity 71-100%, specificity 91-96% and accuracy 89-97%). In 27 patients submitted to both imaging examinations MRI was somewhat superior compared to CT (p > 0.1) and yielded similar results as endoscopic procedures (accuracy of cystoscopy and rectoscopy of 90% and 94%, respectively)., Conclusion: CT and MRI allow to predict involvement of bladder or rectum wall in carcinoma of the uterus with a similar accuracy as endoscopic procedures.

Purpose: To determine the diagnostic value of 3 MR sequences for the diagnosis of adrenal tumors., Material and Methods: Retrospective analysis of 32 adrenal tumors (10 malignant, 15 adenomas, 5 inflammatory, 2 phaeochromocytomas) examined by MRT (1.5 T) using T2 turbo spin echo, chemical shift imaging and dynamic contrast-enhanced gradient echo sequences., Results: Differentiation between malignant and benign adrenal tumours by means of T2-weighted sequences, chemical shift imaging and dynamic contrast-enhanced sequences achieved a sensitivity/specificity of 90%/73%, 100%/68% and 90%86%. Accuracy was 78%, 78% and 87%. By combining the three procedures, sensitivity/specificity/accuracy was improved to 100%/91%/94%., Conclusion: To differentiate adrenal lesions, the following procedures are recommended: demonstration of fat by chemical shift imaging is indicative of an adenoma. In the absence of any lipid content, T2-weighted and dynamic contrast-enhanced sequences can demonstrate inflammatory lesions.

Purpose: The diagnostic value of endorectal magnetic resonance imaging (MRI) in comparison to clinical information and other imaging modalities was analysed in order to define the most accurate preoperative staging method., Methods: 54 patients with biopsy proven prostate carcinoma, who underwent subsequent prostatectomy, were examined with an endorectal surface coil. The results were compared to body coil MRI, digital rectal examination and prostate specific antigen levels. In 37 patients, results of endorectal ultrasound were available., Results: Staging accuracy, sensitivity and specificity of endorectal coil MRI were 83.3%. For body coil MRI, staging accuracy was 59.2%, sensitivity 43.3% and specificity 82.6%, for transrectal ultrasound 59.5%, 36.4% and 91.7% and for the digital rectal examination 55.6%, 26.7% and 91.7%, respectively. Staging accuracy of endorectal MRI was significantly (p < 0.05) superior to that of the other imaging modalities., Conclusion: Endorectal coil MRI allows reliable distinction between localised and advanced tumour stages and is superior to other imaging techniques in this regard. It can thus be recommended for staging in patients with prostate carcinoma.

Background and Study Aims: Endosonography has become the best available method for local staging of primary rectal cancer and diagnosing recurrent local tumor. The aim of this prospective study is to compare the accuracy of endoscopic ultrasound (EUS), using an echo colonoscope (CF-UM 3, CF-UM 20, Olympus optical) to computed tomography (CT), body coil magnetic resonance imaging (MRI) and endorectal coil magnetic resonance imaging (EMRI)., Patients and Methods: From February 1991 to July 1993 90 patients with primary rectosigmoidal tumors (n = 32: 9 women, 23 men, mean age 68 years [range 37 to 84]) or follow-up examinations for recurrent local cancer (patients: n = 58, examinations: n = 93; 41 women, 52 men, mean age 61 years [range 31 to 84]) were investigated. The results of preoperative examinations were compared to histopathological findings regarding T and N stages., Results: In T staging, accuracy of EUS (78%) was superior to CT (50%) and equivalent to both MRI (75%) and EMRI (80%). The accuracy of EUS (84%) in assessing transmural tumor infiltration was superior to CT, MRT and EMRT (50%, 75% and 80%, resp.); however, CT (77%) and MRI (86%) were more accurate than EUS (64%) and EMRI (33%) in assessing N stages. Recurrent local cancer was found in 22 patients. All but one were detected by EUS. Sensitivity, specificity and accuracy in follow-up examinations for recurrent disease for EUS were 95%, 94% and 95%, for CT 75%, 73% and 74%, for MRI 57%, 100% and 70%, and for EMRI 83%, 100% and 90% resp., Conclusions: Endoscopic ultrasound proved to be a safe and accurate method of preoperative staging and early diagnosis of recurrent rectal cancer and was superior or at least equivalent to CT, MRI and EMRI.

Computed tomography continues to be the imaging modality of choice for staging of pancreatic carcinoma. It has an accuracy of over 70% in predicting tumor resectability and a sensitivity of almost 100% in detecting nonresectable pancreatic lesions. Magnetic resonance imaging with the use of recent technical development delivers almost similar results. It can be expected, that introduction of dynamic contrast-enhanced fast sequences will further improve the results of preoperative staging.

A correct staging of clinically localized prostate cancer should nowadays consist of: digital rectal examination (DRE) (+/- -transrectal ultrasound [TRUS]) bone scan abdominal computed tomography or body coil magnetic resonance imaging (+/- laparoscopic lymph node dissection according to the PSA level) endorectal surface coil MR imaging (if available) The above-mentioned methods are discussed with preference to the new technology of endorectal surface coil magnetic resonance imaging (E-MRI) of the prostate.

A persistent or new mass in the anterior mediastinum after chemotherapy for mediastinal lymphoma poses a major differential diagnostic problem. Misinterpretation as a persistent or recurrent tumor may lead to additional unnecessary and potentially harmful therapy. Benign mediastinal tumors, albeit very rare, need confirmation by biopsy since they cannot be distinguished by radiological methods from persistence or relapse of lymphoma. We present a case report of a patient with diffuse thymic hyperplasia following successful chemotherapy for nodular sclerosing Hodgkin's disease, with a review of the literature.

The assessment of abdominal vessels with conventional methods is invasive and frequently does not yield an accurate diagnosis, particularly in the evaluation of the portal venous system. MR angiography is non-invasive and is well suited for the examination of abdominal vessels. Both vessel morphology and intravascular flow patterns can be characterized with this method. Clinical indications include portal hypertension, portal vein thrombosis, portosystemic shunts, assessment of congenital anomalies, thrombus, and tumor propagation into the inferior vena cava and the renal veins, proximal renal artery stenosis, and assessment of the pelvic arteries and veins. In the future, MR angiography may become an important part of the non-invasive evaluation of abdominal and pelvic vessels.

The aim of the present study was to compare the diagnostic value of spiral CT with that of conventional CT in hilar pathologies. Initially, we determined the minimum amount of contrast material necessary which still produced a good enhancement of the pulmonary vessels. After testing with 20 patients, we found that a bolus of 60 ml injected at a rate of 6 ml/s was optimal. This was then used for 30 patients who were subsequently examined with both CT techniques. In nearly every case, the spiral CT examination produced a significantly better enhancement of the pulmonary vessels than conventional CT. In 35 patients the diagnostic value of the spiral CT was compared with the conventional method. In 19 cases (54%) its diagnostic value was higher, and for 7 of these (20%), an optimal diagnosis was made with spiral CT whereas no clear diagnosis was possible with conventional CT.

Inflammatory disease of the female pelvis can be diagnosed both on the basis of clinical symptoms and complementary ultrasound. The role of CT and MRI is limited to complicated cases. CT guidance allows the biopsy needle to be localized precisely for diagnostic or therapeutic punctures. Furthermore, CT and MRI play an important role in the evaluation of prolonged puerperal fever of unknown origin: endomyometritis is associated with characteristic features in MRI, whereas puerperal ovarian vein thrombosis is best diagnosed using MR angiography. For other rare causes, MRI and CT have to be used according to clinical need.

Spatial resolution of MRI within the true pelvis can be increased by a factor of 12 using an endorectal coil. The value of this new method for demonstrating the prostate, the rectum, the cervix and vagina and of pathological processes of these organs was examined in 89 patients and the results compared with conventional body coil MRI. In 25 patients who underwent radical surgery the results of the preoperative studies were compared with the histological findings. Detailed recognition of anatomical structures was markedly improved by using the endorectal coil. Diagnosis of carcinoma of the prostate and extension of the tumour was accurately assessed in 33 patients. Preoperative staging was correct in 87%, compared with 73% when using a body coil. The difference was less marked in examinations for carcinomas of the rectum, the cervix and vagina. Nevertheless, staging was more accurate in a few cases with a better recognition of recurrences. MRI with endorectal coils will have an important role in diagnosis of carcinomas of the prostate in the future. Its use in the diagnosis of carcinomas of the rectum and cervix must be subject to further studies.

The veins in the pelvis and lower limbs have been demonstrated by means of magnetic resonance angiography (MRA) in 11 normals and in 20 patients, using a "time-of-flight" technique (TOF). Using normals, changes in the measurement parameters were used in order to optimise the examination protocol; consequently, the internal and external iliac veins and the superior and inferior gluteal veins could be identified in all cases and the internal pudendal veins in 6 out of 11 cases. This examination protocol was then used in patients with clinical suspicion of lower limb or pelvic vein thrombosis. Comparison of the MRA findings with those of phlebography (7 cases), duplex sonography (6 cases) and colour Doppler examinations (11 cases) showed that MRA was better for diagnosing thrombosis of the internal iliac veins (10 cases) than the other methods. In two patients thromboses of the common iliac veins and the inferior vena cava were demonstrated which were missed by colour Doppler examination. On the basis of our present experiences, MRA, using a two-dimensional TOF technique, appears to be a reliable non-invasive technique for demonstrating the veins of the pelvis and thigh.

A previously well 24-year-old man complained of persistent epigastric pain after a session of intensive muscle building exercise especially of the abdominal muscles. The abdomen was diffusely tender without guarding. There was an increased concentration of bilirubin (64.7 mumol/l), GOT (117 U/l), GPT (529 U/l) and alkaline phosphatase (150 U/l). Ultrasound examination showed a widening of the choledochal duct to 11 mm without signs of gallstones. Endoscopic retrograde cholangiography additionally revealed contrast-medium extravasation from the left hepatic duct. Computed tomography, performed immediately afterwards, confirmed the extravasation, while liver and pancreas were unremarkable. Laparoscopy revealed a 5 mm tear in the left hepatic duct, close to the hepatic duct bifurcation with bile effusion into the peritoneal cavity. The latter was rinsed endoscopically with Ringer's solution and drains were placed in the omental bursa and subhepatically in the region of the bile leak. To relax the sphincter Oddi glycerol trinitrate was administered postoperatively, for the first five days 72 mg/24 h intravenously, then for nine days twice daily 20 mg by month. No more bile drained as early as the second postoperative day and the patient was free of symptoms 2 weeks later.

The fast spin echo (FSE) technique leads to time saving by individual phase coding of several spin echoes within one repetition interval. The new sequencing was compared quantitatively and qualitatively with conventional spin echo sequences in 30 patients with gynaecological pelvic disease. The signal-to-noise ratio was higher on FSE images in all tissues but to a variable degree. This led to an increased contrast-to-noise ratio, particularly between fat and solid structures, and to a reduction in the contrast between fat and fluid. Artifacts were reduced in FSE sequences leading to improved image quality in 83% and increased diagnostic information in 10%. This is of particular advantage when using time consuming T2-weighted sequences, which are necessary for the examination of the female pelvis.

Twenty-one children with predominantly solid tumours detected by US were also examined by MRI (7 neuroblastomas, 2 Wilms tumours, 3 hepatoblastomas, 2 germinal cell tumours, 1 ganglioneuroblastoma, 1 gangliocytoma, 1 Cushing's adenoma, 1 phaeochromocytoma, 1 retroperitoneal rhabdomyosarcoma, 1 diffuse lymphangiectasia of a kidney, 1 splenunculus). The findings from both methods were compared with respect to the identification of the organ involved, extent of the tumour, effect on neighbouring structures and tissue characteristics. US and MRI were of equal value in defining the origin of the lesion and in demonstrating pathological enlargement of lymph nodes. Exact tumour extent could be better demonstrated with MRI because of the ability to perform multiplanar sections and to demonstrate intrathoracic and intraspinal spread. MRI was superior in 9 cases in demonstrating tumour structure and in 6 cases in the evaluation of vascular involvement and vascular anatomy. MRI is therefore recommended as an additional method to US for diagnosis and for treatment planning.

Sclerosing peritonitis is a serious complication of CAPD characterised by thickened peritoneal membranes which lead to decreased ultrafiltration and intestinal obstruction. The roentgenographic signs of SP were analysed in 11 patients who underwent plain x-ray of the abdomen, follow-through examinations of the small bowel, ultrasonography and computed tomography. Results were correlated with the histological degree of SP. Besides the non-specific findings of intestinal obstruction, patients with histologically marked SP had loculated fluid collections, thickening of the bowel wall and/or peritoneum, peritoneal calcifications and thickened peritoneal membranes. Due to the fact that postoperative complications often occur in patients with SP, detection of the radiological signs should lead to cautious surgical interventions and changeover to haemodialysis.

We describe 3 cases of eosinophilic pneumonia of unknown etiology with atypical clinical findings diagnosed by bronchoalveolar lavage (BAL). In 2 patients with subacute symptoms and restrictive ventilatory dysfunction there was no eosinophilia in peripheral blood, and chest X-ray showed a bilateral acinar and mixed interstitial-acinar pattern respectively. Transbronchial lung biopsies revealed only nonspecific changes. The third patient had acute respiratory failure and the eosinophils in peripheral blood were 1500/microliters. Chest X-ray demonstrated only minimal interstitial changes. In all instances the eosinophilic pneumonia was diagnosed by a marked BAL-eosinophilia of 25 to 45%. No specific etiology could be detected for the eosinophilic lung disease. The response to treatment with corticosteroids was prompt.

Ultrasonography is the method of first choice for the rational work-up of abdominal pathologies. The results and limitations of this method for diagnosis of diseases of the gallbladder, bile ducts, liver, pancreas, spleen, kidney and urinary tract, adrenal glands, vessels and lymph nodes, female pelvis and gastrointestinal tract are presented in a short overview. Particular reference is made to a critical approach, emphasizing relevant further investigations.

52 patients with bronchogenic carcinoma were studied preoperatively by means of conventional tomography and CT. The results were compared with surgical findings to evaluate the accuracy of these methods in detecting mediastinal lymph node involvement. 323 mediastinal lymph nodes were identified by CT and 237 of these were studied histologically. In 25% of lymph nodes with diameter between 0.5 and 1 cm metastases could be identified. On the other hand, 25% of lymph nodes measuring up to 3 cm did not contain metastases. The results varied in different regions (pre- and paratracheal, azygos region, aorto-pulmonary, subcarinal). The probability of involvement of small nodes was doubled if there were in regions neighbouring metastases. In view of the high incidence of false positive and false negative CT findings, conventional methods were sufficient in the presence of definite pathological findings.

Magnetic resonance imaging (MRI) is a valuable noninvasive method for evaluating the female and male pelvis. The advantages of MRI include direct multiplanar imaging and excellent contrast resolution. The superb soft-tissue contrast provides unique depiction of the characteristic zonal architecture of the uterus, vagina and the prostate. The role of MRI in the pre- and posttherapeutic evaluation of carcinoma of the endometrium, cervix, ovaries, vagina and prostate is described. Our own experience with patients with a suspected tumor recurrence shows that MRI is able to distinguish tumor recurrence from posttherapy fibrosis if the interval between therapy and MRI is more than one year. MRI seems not to be useful in differentiating these entities at an early stage after treatment.

The use of magnetic resonance imaging (MRI) for diagnosis and preoperative staging of renal cell carcinoma was evaluated in 79 patients with 88 tumors. Gradient-echo and spin-echo images before and after intravenous administration of Gadolinium-DTPA were compared with the results of computed tomography (CT) and histologic staging. The two imaging techniques had comparable results: T-stage was predicted correctly with CT in 78.4% and with MRI in 84.0% of the cases, while the N-stage was accurately assessed in 81.8% and 79.5%, respectively. MRI had some advantages in diagnosing perirenal tumor spread and in excluding an infiltration beyond Gerota's fascia. Therefore, MRI is a true alternative to CT for staging large renal cell carcinomas and especially for patients with contraindications for iodinated contrast agents.

CT and MR imaging are of minor importance for the preoperative diagnosis of rectosigmoid carcinoma. A synchronous colon tumor can be excluded with a barium enema, while an accurate diagnosis of liver metastases is possible using real-time ultrasonography. However, post-operative management requires the use of tomographic methods: MR imaging has proved to be more accurate than CT for differentiation between local recurrence and post-operative scars. Therefore MRI should be the method of choice after surgery for rectosigmoid carcinoma in all patients without postoperative baseline examinations.

Based upon the results obtained in 346 patients, the diagnostic value of conventional techniques, ultrasonography, computed tomography and magnetic resonance imaging in the detection of peritoneal tumor spread is analyzed. Since such signs as ascites, mesenteric and omental infiltration and peritoneal masses are non-specific, various conditions have to be considered in the differential diagnosis. None of the imaging modalities can exclude intraperitoneal tumor spread.

64 patients were operated on for carcinoma of the oesophagus during a five-year period (1/83 to 1/88) at the Department of Surgery of the University of Cologne; 95.3% of these suffered from squamous cell carcinoma. A preoperative CT of the thorax was performed in 38 patients, 13 of whom underwent abdominothoracic surgery and 25 blunt oesophagus dissections. The CT and plain diagnostic results were compared retrospectively and postoperatively with the intraoperative or histological findings. Three of seven oesophageal carcinomas of up to 2 cm size were not identified by CT. Infiltration of adjacent mediastinal structures by T3 carcinomas was detected in 16 of 22 cases with 3 false positive findings. In blunt oesophagus dissection the preoperatively diagnosed lymph node status agreed with the histological findings in more than 80% of the cases; a limitation, however, was the fact that only those lymph nodes could be assessed that clung to the resectate. In contrast, agreement was seen in only 7 of 13 cases (with 6 false negative findings) after abdominothoracic resection of oesophageal carcinomas. On the whole, there was agreement between preoperative and histological staging according to the TNM classification (UICC = in 50% of the cases, whereas in almost 40% (n = 15) the size or extension of the tumour growth had been underestimated preoperatively. Hence, the value of CT for the preoperative staging of oesophageal carcinoma is restricted.

One hundred and forty-six intracranial hematomas in 129 patients were examined by MRI (136 examinations) and CT (147 examinations). Even using a high field MR system (1.5 T) and gradient-echo sequences, CT was the more sensitive method during the acute phase (46% compared with 93%). During the sub-acute phase, MR was superior to CT (97% compared with 58%), as it was in the chronic phase (93% compared with 17%). Petechial bleedings and discreet foci of contusion could only be demonstrated by MRI. Moreover, MRI showed evidence of residues from hemorrhage (signal reduction due to hemosiderin deposition) long after CT has become normal. Analyses of MRI images allows one to date the bleed and to distinguish between a) the formation of clot in a haemorrhagic cavity, b) bleeding into the tissues and c) a liquefying hematoma. Bearing in mind this classification, the localisation of the hematoma and the clinical findings mostly allow it is possible to determine the cause of the bleeding. Another advantage is the certain detection of vessels supplying arterio-venous malformations and cavernous hemangiomas.

Taking the results of 307 cases with peritoneal carcinomatosis, the diagnostic value of ultrasonography and computerized tomography in the detection of peritoneal spread of gynaecological and gastrointestinal tumors is discussed. Ascites is the most important, though nonspecific, symptom which can be detected with the greatest accuracy. Peritoneal nodular lesions as well as omental and/or mesenteric involvement can easily be missed by both methods. Thus, staging-laparotomy cannot be replaced in the management of gynecologic malignancies.

The use of fast gradient echo sequences enable reduction of the acquisition times in MR imaging, allowing examinations during suspended respiration. Furthermore, repeated single slices in the same position after administration of a paramagnetic contrast agent provide dynamic evaluation of tissue perfusion. These new diagnostic modalities were applied for imaging normal adrenal glands in 128 cases and for differentiation of 83 adrenal tumors in 74 patients. CT remains the imaging method of choice for the detection of adrenal masses, due to the higher spatial resolution. Fast gradient echo MRI offers the possibility of differentiation between benign and malignant adrenal lesions. The 70% accuracy reached with precontrast scans can be augmented to 90% using dynamic contrast-enhanced studies.

The new technique of rapid magnetic resonance imaging (MRI) with a paramagnetic contrast agent provides excellent imaging of the kidneys and their lesions. MR imaging of this anatomical region at short breath holding intervals matches the well-known quality of computed tomography (CT) for the first time. MR and CT studies were performed on 36 patients with proven renal cell carcinoma. Different investigators evaluated the staging of the tumor by means of both techniques in a prospective study. In all patients a radical nephrectomy was performed. Surgical and pathological findings were compared. Though little difference was found in diagnostic value between the two systems, MRI results concerning the T-stage were better. Venous invasion was clearly shown by MRI without the use of contrast medium. Furthermore, sagittal and transaxial images provided a more direct assessment of the extent of the tumor and its demarcation to healthy parenchyma. Thus, MRI is helpful in planning of the surgical approach when organ-sparing excision of renal tumors is to be performed.

In 56 patients with abdominal abscess typical radiological abscess sings were analized to establish a rational and stepwise use of imaging procedures. Plain radiographs of the abdomen should be carried out at first because of their large diagnostic possibilities and standardized practicability. In addition with ultrasonography the diagnosis is possible in almost 90% of the cases. Contrast medium examination are rarely of diagnostic value. Computed tomography should be used in the remaining unclear cases and for planning of further surgical treatment.

Using representative case studies the diagnostic problems of colonic infiltration in cases of gastric and pancreatic neoplastic or inflammatory lesions are discussed. Typical signs in both barium enema and ultrasonography lead to the detection of secondary bowel wall lesions. Characteristic intraperitoneal pathways of spread and roentgen-morphologic features are important in the attempt to differentiate inflammatory from malignant infiltrations. In these cases ultrasonography, showing a diffuse thickening of gastric or bowel wall, is a useful additional diagnostic tool, which gives further information about topographical relations in the abdomen.

The problems of extracolic-infiltrative lesions of the sigmoid colon and recto-sigmoid junction are discussed, based on representative case studies. Because of the localisation of these bowel segments in the lower peritoneal cavity, they can be reached by direct infiltration of contiguous tumors--especially carcinoma of the ovary--or by seeding into the pouch of Douglas and the sigmoid mesocolon. In many cases characteristic roentgen-morphologic features indicate a secondary infiltration, but inflammatory and malignant lesions have to be differentiated. The differential-diagnosis must consider also diverticulitis, endometriosis and extracolic growth of colonic carcinoma. Additional ultrasonography and computed tomography may help to clear topographical relations and to detect direct and indirect signs of peritoneal carcinomatosis and abscess.

Pre-operative computed tomograms were obtained in 52 patients with histologically confirmed peripheral bronchial carcinomas and possible involvement of the pleura and thoracic wall was analysed. The results were compared with the operative and histological findings. Thickening of the pleura and of the sub-pleural fat line was observed in 24 cases. Amongst these patients there was only one case with histologically confirmed pleural infiltration. In 17 patients the sub-pleural fat line was obliterated, or could not be defined. Amongst these, 11 showed tumour extension to the pleura or soft tissues of the chest wall. It is concluded that the most suspicions sign of pleural tumour extension is absence of the sub-pleural fat line. The more frequently observed pleural thickening cannot be considered as a reliable sign for pleural involvement.

Plain radiographs of the abdomen in supine and left decubitus position were combined with additional contrast medium examinations, ultrasonography and computed tomography and used for diagnosis in 47 patients with surgically verified abdominal abscesses. Typical abscess signs were analysed to establish the stepwise use of imaging procedures. Diagnosis of an intraperitoneal or retroperitoneal abscess can be made in over 50% of the cases by accurate interpretation of abdominal plain films. If combined with ultrasonography, diagnosis is possible in even almost 90% of the cases. Computed tomography may additionaly show the exact localisation and extension of the lesion and is mainly used in planning further surgical treatment.

Involvement of the central nervous system in acquired immune deficiency syndrome (AIDS) is usually due to opportunistic infections; these frequently offer a difficult differential diagnostic problem. Imaging methods play an important part in the elucidation of symptoms. CT and MR findings were analysed in 13 patients with AIDS and neurological symptoms. Some infections of the central nervous system (encephalitis of unknown aetiology, cytomegalic encephalitis, meningitis) may show cerebral atrophy or even no morphological changes. Toxoplasmosis and PML are the most common opportunistic infections typical changes on CT and MR may lead to diagnosis. MR offers advantages compared with CT in its higher sensitivity for the demonstration even of small lesions.

The limitations of differentiation of retroperitoneal and pelvic paraureteral lesions causing ureteral obstruction are discussed in 84 cases using computerized tomography. The unspecific feature of a plate- and weblike connective tissue pattern in tumors, scar formation and inflammatory process is demonstrated

In the FFE-sequence the new parameter "flip angle" introduces, besides the possibility of fast MR-imaging, an increased variability of external MR parameters. Experimental studies in healthy volunteers and patient examinations were carried out to establish the most useful parameter combinations giving reasonable contrasts. Variation of external parameters allows a manipulation of image contrasts: using small flip angles in combination with longer TE good T2-weighted images can be achieved; large flip angles with short TR and TE produce a sufficient T1-weighting. In this way the FFE sequence proves to be a valuable method for rapid assessment of pathologic lesions.