[Frequency and causes of civil and criminal proceedings in radiology. Analysis of a survey]

The eagerness of German patients to go to court on account of actual or suspected malpractice of their physicians has increased over the years, as is the case in other Western countries. Media coverage has given rise to criticism of physicians and their services rendered more than before. This naturally also concerns the discipline of radiology, even though the probability of a radiologist being accused in a lawsuit is clearly minor in comparison to the surgical disciplines. In contrast to other fields, the X-ray pictures are always available for a second opinion. In this study, 4760 radiologists were sent a questionnaire by mail and 1503 answered. The questionnaires were evaluated regarding interrogative and informative data from pending or completed proceedings. Lawsuits were directed towards the assessment of examinations (38%), the actual performance of an examination (30%) and not towards providing patients with information as we had expected. Angiographies, mammographies, and radiographies were the most frequent reasons for instituting proceedings. The majority of litigating patients was between 40 and 50 years old. The proceedings led to civil convictions in 30% and criminal convictions in 5.5%. Of the physicians accused of incorrect conduct, 73% were of the opinion that they had been treated unjustly, 26% supported the reproach as justified, and the rest had formed no opinion. Physicians in private practice and senior consultants (70%) were most frequently sued.

Long-term MRI and clinical follow-up of symptomatic and presymptomatic carriers of dysferlin gene mutations

We report the results of a longitudinal study involving MRI and clinical follow-up in nine siblings from four families with Miyoshi myopathy (MM). All individuals carried pathogenic dysferlin gene (DYSF) mutations with six of them suffering from symptomatic disease and three being presymptomatic. In presymptomatic subjects, MRI was sensitive to detect alterations in muscle tissue years before disease onset. The first MRI alteration to disclose was evidence for myoedema in dorsal compartment muscles of the legs followed by fatty degeneration. Moreover, MRI changes anticipated the topography of subsequent clinical muscle involvement and progressed from distal to proximal dorsal leg muscles. In symptomatic subjects, MRI changes reflected the pattern and severity of clinical muscle involvement. MRI evidence, however, suggests that muscle involvement is much more prominent in early disease stages than clinically seen. Clinical follow-up up to 8 years made evident that MM onset occurs at a mean age of 18.4 years. The most prominent initial deficit was impaired tiptoe gait due to muscle plantarflexor dysfunction followed by impaired dorsiflexor function. Dorsal compartments were predominantly affected not only in distal but also in proximal leg muscles, and a more rapid progression was noticed during the early phase of the disease. Our data suggest that MRI is a helpful diagnostic tool for an early diagnosis of MM and other distal myopathies since it provides sensitive and topographic information about initial and even preclinical muscle involvement. This is of particular relevance in Miyoshi myopathy because distinct CK elevation is present long before its clinical onset and often misdiagnosed as "idiopathic".

Der Hirnabszess in der Diffusionswichtung und Unterschiede zum zystischen Hirntumor

PURPOSE

The clinical usefulness of diffusion-weighted imaging (DWI) was evaluated in patients with brain abscesses in comparison to patients with cystic brain tumors.

MATERIAL AND METHODS

Five patients with surgically confirmed brain abscesses underwent beside a brain MRI examination with contrast media application diffusion weighted imaging. Apparent diffusion coefficients (rADC) in three orthogonal diffusion gradient were calculated. The same protocol was used to examine 5 patients with cystic brain tumors.

RESULTS

Showing an rADC of 0.33 x 10(-3)/mm(2)/s abscesses have a highly restricted diffusion in comparison to cystic brain tumors with an rADC of 1,67 x 10(-3)/mm(2)/s.

CONCLUSION

Diffusion weighted imaging is a usefull diagnostic tool in the work up of brain abscesses.

Endovascular interventions on persistent sciatic arteries

PURPOSE

To report our experience with interventional procedures used to treat complete and incomplete persistent sciatic arteries (PSA).

CASE REPORTS

Three female patients with PSAs displayed varying symptoms referable to this rare anatomical variant. In the first woman, a 1-year history of intermittent lower limb ischemia and an acute event prompted angiography, which demonstrated proximal occlusion of 2 crural vessels and a partially thrombosed sciatic artery aneurysm. To prevent further embolism, the aneurysm was excluded with a stent-graft. Endograft patency and aneurysm exclusion have been maintained up to 22 months. In a 41-year-old diabetic with chronic limb ischemia and digital gangrene, a flow-limiting stenosis of the sciatic artery was stented, restoring adequate pedal perfusion. The stent remained patent at the 18-month follow-up. The third patient suffered from a tumor-related pelvic hemorrhage originating from retrograde perfusion through the PSA, which had been ligated during previous surgery. Attempted embolization via a collateral connection between the incomplete PSA and the popliteal artery failed, and the patient died.

CONCLUSIONS

Vasculopathies involving the sciatic artery are uncommon but may be amenable to interventional techniques, such as coil embolization and stent implantation. PSA aneurysm exclusion with a stent-graft may represent a new therapeutic alternative to standard surgery that obviates potential sciatic nerve damage, but the durability of the repair remains to be determined.

Hippocampal activations during repetitive learning and recall of geometric patterns

Hippocampal activation is required for episodic memory. Encoding and retrieval of novel and memorable items have been related to different locations in the hippocampus; however, the data remain ambiguous. The application of a newly designed keyboard allowed investigation of brain activation during encoding and free immediate and delayed recall with functional magnetic resonance imaging (fMRI) in young healthy controls (n = 12). Because of the repetitive learning and recall conditions, an individual learning gradient was used to contrast neural activity at different individual levels of novelty. During learning, subjects were asked to memorize 10 geometric patterns requiring the establishment of intra-item associations for memorization. After learning, subjects were asked to recall the items actively via the keyboard. Learning and recall were alternated five times. Delayed recall was scanned about 15 min after the fifth immediate recall condition without subjects having seen the items again. Left-sided anterior hippocampal activity was observed during conditions of initial learning as well as maximum recall. Neural activity during delayed recall did not reveal hippocampal responses and was characterized by a transition of neural activity from occipitoparietal regions to bilateral temporal cortices. We conclude that both lateralization and segregation depend on the specific relational characteristics of the stimuli requiring establishment of intra-item associations for encoding as well as retrieval. The absence of hippocampal activation during delayed recall together with the increase of lateral temporal involvement possibly corresponds with an emerging transition from episodic to long-term memory.

Results of applying ADCON-L gel after lumbar discectomy: the German ADCON-L study

OBJECT

Failed-back syndrome is still an unsolved problem. Use of ADCON-L gel, already commercially available, has been proven to reduce postoperative scarring in animal experiments. The authors of two controlled clinical studies have also shown positive results when applying the gel. They did not, however, establish patient-oriented endpoints. The authors report a study of ADCON-L in which they focus on patient-oriented endpoints.

METHODS

Patients with lumbar disc herniation were randomized to an ADCON-L-treated or control group. Therapeutic success was evaluated using the validated Hannover Questionnaire on Activities of Daily Living (FFbH) 6 months after surgery. The study took place between November 14. 1996, and April 20, 1998, in eight neurosurgical centers in Germany. A total of 398 patients was recruited; 41 patients dropped out during follow up. The mean functional FFbH score (100 points = all activities are possible without problem; 0 points = no activity is possible) was 78.5 points in the ADCON-L-treated group compared with 80 points in the control group. Furthermore, in terms of secondary outcome variables, the ADCON-L group did not have an advantage over the control group. Only the mean magnetic resonance imaging score showed a slight advantage of ADCON-L over the control group.

CONCLUSIONS

The authors found no positive effect of treatment with ADCON-L gel in patients in whom one-level lumbar microdiscectomy was performed. Because of its rather large sample size and its homogeneity, the study had sufficient power to detect even small differences between the two groups.

Thrombus formation in aortic endografts

PURPOSE

To examine the incidence of intraprosthetic thrombotic deposits in aortic endografts.

METHODS

Transfemoral implantation of tube or bifurcated stent-grafts was performed in 82 patients (75 men; average age 67.7 years, range 25-88) for treatment of aneurysms of the abdominal (n = 73) or thoracic (n = 9) aorta in a 3.5-year period. Patients underwent 3-phase helical computed tomographic (CT) examinations at 3-month intervals. The length and cross-sectional area of any thrombotic deposits were measured from axial and 3-dimensional CT images.

RESULTS

Over a 12.1-month mean follow-up, intraluminal deposits of thrombotic material were observed in 19 (23.2%) patients, all with infrarenal endografts that were predominately of a bifurcated design. The first signs of thrombus formation occurred on average 7 months postoperatively (range 1 week to 20 months). In 16 patients, nonocclusive deposits of thrombotic material were seen in the aortic segment of the endograft; a graft limb was involved in 5 patients. Three graft limbs occluded owing to kinking; no thrombus was seen on CT scans taken prior to occlusion. In 3 cases the thrombotic deposits disappeared completely from the prosthesis lumen during follow-up.

CONCLUSIONS

Based on this small experience, nearly 1 in 5 patients may experience some degree of intraluminal thrombus following endovascular treatment of aortic aneurysms. Whether the deposition of thrombus is influenced by the geometry of the aortic stent-graft or by flow conditions within the prosthetic lumen must be determined in future studies.

Percutaneous techniques for managing maldeployed or migrated stents

PURPOSE

To report our experience in the percutaneous management of dislocated endovascular stents.

METHODS

During a 6-year period, 28 (2.7%) patients with a maldeployed or migrated endovascular stent (20 Palmaz, 5 Wallstent, 2 Memotherm, and 1 AVE) were recognized among 1021 patients undergoing noncardiac vascular stent procedures. Percutaneous stent management was performed using balloon catheters, gooseneck snares, grasping forceps, or additional stent implantation on the basis of the stent type, degree of expansion, mechanical characteristics, and location of the stent.

RESULTS

Three stents that embolized into the pulmonary artery were left in situ, but percutaneous management was successful in 23 (92%) of the remaining 25 dislocated stents (12 venous and 13 arterial stents). Twelve stents were repositioned in an alternate, stable position or the primarily intended location; 4 stents were anchored by a second stent, and 7 stents were removed percutaneously. In the 2 failed cases, the stents were retrieved using a minor surgical procedure. There were 2 minor groin hematomas but no secondary complications during a median follow-up of 26.2 months (range 1-62).

CONCLUSIONS

Percutaneous management of migrated or maldeployed endovascular stents is highly effective with few complications. On the basis of our findings, these techniques should be considered the therapy of choice.

Multimodal cranial neuronavigation: direct integration of functional magnetic resonance imaging and positron emission tomography data: technical note

OBJECTIVE

This is the first report of the direct integration of functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) data into cranial neuronavigation.

METHODS

In a patient with a left precentral oligodendroglioma (World Health Organization Grade III), the Zeiss MKM system (Carl Zeiss Co., Oberkochen, Germany) was used for navigation based on thin-slice, T1-weighted, contrast-enhanced magnetic resonance imaging (MRI) scans. fMRI and methionine PET data were integrated by landmark matching, with reference to skin fiducials.

RESULTS

The inaccuracy of the image fusion between fMRI and T1-weighted MRI data was 1.7 mm, that between PET and T1-weighted MRI data was 4.3 mm, and that for the subsequent registration of the navigation was 1.2 mm. The correct fMRI localization of the precentral gyrus was intraoperatively verified by cortical somatosensory evoked potential (phase-reversal) monitoring. Although the tumor was not clearly defined in the MRI scans, [11C]methionine PET demonstrated a clear tumor border, enabling us to achieve gross total tumor removal without postoperative functional deficits.

CONCLUSION

Functional neuronavigation permits observation and preservation of relevant brain areas. Other functional areas (such as short-term memory areas) that can be detected only by fMRI might also warrant future monitoring. The simultaneous integration of fMRI and PET data adds a new dimension to cranial neuronavigation, enabling the observation of tumors in relation to functional cortical areas (in our case, the motor strip).

Diagnosis of papillomas of the breast: value of magnetic resonance mammography in comparison with galactography

The aim of this study was evaluation of MRI alone and in combination with mammography and galactography in the diagnosis of intraductal papillomas. From 1994 to 1998, a total of 48 women presenting with pathologic mammary secretion underwent galactography and magnetic resonance mammography (MRM). Thirty-five patients aged 16-71 years (average age 46 years) subsequently underwent surgery or diagnostic puncture and the histologic findings were compared with the results of the radiologic examination. Histology revealed papillomas in 16 cases. In 6 of these patients, there was associated malignant degeneration. Malignancy without associated papilloma was observed in 3 cases. Galactography displayed a sensitivity of 94% and a specificity of 79% with five false-positive findings and one false-negative finding in the recognition of intraductal papillomas. Malignant processes were detected by mammography/galactography in only one instance. Magnetic resonance mammography visualized pathologic contrast medium uptake in 8 of 9 cases of malignant disease (sensitivity 89%). One patient with in situ ductal carcinoma escaped detection with MRM. Papillomas showed no or below-the-threshold-lying contrast uptakes with no specific sign suggestive of papilloma. Galactography in combination with mammography remains the primary diagnostic procedure in cases of pathologic mammary secretion or suspected papilloma. The addition of MRI permits exclusion of malignant disease with a high degree of certainty; thus, expectant management in individual cases with negative findings appears justified.

Diffusion-weighted MRI: detection of cerebral ischemia before and after carotid thromboendarterectomy

PURPOSE

Conventional postoperative evaluation of patients following carotid thromboendarterectomy (TEA) consists of a clinical neurologic examination to assess neurologic deficits, color duplex ultrasound to document the surgically reestablished patency of the carotid artery, and CT for exclusion of postoperative ischemic infarctions. Recent studies prove that diffusion-weighted MRI is more sensitive in the detection of fresh insults than conventional MRI and CT. The objective of the study was to ascertain the incidence of clinically asymptomatic peri-and postoperative ischemic infarctions visualized at MRI.

METHOD

We included 52 patients in the study. Fifty-one patients (31 men, 20 women; average age 68 years) underwent cranial MR examination including a diffusion-weighted sequence at 24 h prior to carotid TEA and again 24 h following the procedure. One patient did not agree to participate.

RESULTS

In 29 of 51 patients (56%), neither the pre-nor the postoperative MR scans showed any diffusion abnormalities. In 16 patients (31%), however, preoperative MRI detected fresh ischemic insults. In nine patients (17.6%), the size of the insult resulted in surgery being postponed for 4 weeks. In six patients (11.8%), postoperative MRI returned findings of fresh disturbances of diffusion suggestive of ischemia that were not visualized on preoperative scans. Discrete neurologic deficits were observed in only two (3.9%) of these patients. Deficits were transient and disappeared within 72 h.

CONCLUSION

Our findings underscore MRI's capacity for visualizing perioperative ischemic events. Moreover, MRI provides evidence of clinically asymptomatic embolisms that occur perioperatively.

MRI in the diagnosis of small bowel disease: use of positive and negative oral contrast media in combination with enteroclysis

The aim of the study was to evaluate the additional findings of MRI following small bowel enteroclysis and to compare the efficacy of negative and positive intraluminal contrast agents. Fifty patients with inflammatory or tumorous small bowel disease were investigated by small bowel enteroclysis and consecutive MRI using breathhold protocol (T1-weighted fast low-angle shot, T2-weighted turbo spin echo). Patients were randomly assigned to either receiving a positive oral (Magnevist, Schering, Berlin, Germany) or a negative oral MR contrast media (Abdoscan, Nycomed, Oslo, Norway). The pattern of contrast distribution, the contrast effect, presence of artifacts, as well as bowel wall and extraluminal changes, were determined and compared between the contrast type using Fischer's exact test. Sensitivity, specificity, and diagnostic accuracy for MRI and enteroclysis were calculated. Twenty-seven patients had clinically proven Crohn's disease and two patients surgically proven small bowel tumours. Magnetic resonance imaging had important additional findings as abscesses and fistulae in 20 patients. Surgically compared sensitivities were 100 and 0% for MRI and enteroclysis, for the detection of abscesses, and 83.3 and 17 % for the diagnosis of fistulae, respectively. Bowel wall thickening was more reliably detected with use of positive oral contrast media without intravenous enhancement (p < 0.001), whereas postcontrast negative oral contrast media allow for a superior detection (p < 0.001). T2-weighted sequences were necessary with use of negative oral contrast media, because loop abscesses may be masked. Magnetic resonance imaging should be performed in all patients with suspicion of extraintestinal complications, because the complications are more reliably detected by MRI. Negative oral contrast media show advantages with the use of intravenous contrast but can mask loop abscesses using only T1-weighted imaging.

Endograft treatment of anastomotic aneurysms following conventional open surgery for infrarenal aortic aneurysms

OBJECTIVE

to evaluate the use of endograft therapy for treating anastomotic aneurysm following open surgical repair of infrarenal aneurysms of the abdominal aorta.

METHODS

four male patients (age 47-75 years) at high surgical risk (ASA IV n=3, ASA III n=1) developed secondary aneurysms at the site of the central (four aneurysms) and additional peripheral (two aneurysms) anastomosis of their tube or bifurcation prosthesis an average of 13 years (range 1-23 years) after conventional open surgical correction of infrarenal aneurysm of the abdominal aorta. In two patients, there was covered rupture of the aneurysm sac. The aneurysm diameter was 4.8 cm, 8.0 cm, 7.4 cm, 7.0 cm, respectively (mean 6.8 cm). Follow-up included helical CT imaging at 1 week, 3 months and 6 months postoperatively.

RESULTS

anastomotic aneurysm was successfully treated in all four cases. No evidence of endoleak was observed during the follow-up period. Two patients died 14 and 18 days after surgery due to myocardial infarction and cerebrovascular accident. The endovascular repair of the two patients who died was intact.

CONCLUSION

although no long-term results are available, the use of a graft-in-graft method to repair anastomotic aneurysms following conventional implantation of tube or bifurcation prostheses appears to be effective, particularly in patients at high surgical risk.

Does successful embolization of endoleaks lead to aneurysm sac shrinkage?

PURPOSE

To determine whether embolization of endoleaks after endovascular repair of aortic aneurysms is associated with a decrease in the diameter of the aneurysm.

METHODS

Fifteen patients (13 men; median age 76 years) demonstrated primary endoleaks persisting > or =3 months after endovascular abdominal aortic aneurysm repair with a variety of commercial endografts. In 8 patients, coil embolization failed to completely obliterate the leak, whereas embolotherapy proved successful in the remaining 7 patients. Surveillance of endoleaks and the effect of their embolization on aneurysm size were followed with serial computed tomographic (CT) scans. Follow-up after embolization extended for at least 12 months.

RESULTS

Patients with persistent leak exhibited a slight increase in mean aneurysm area from 21.41+/-4.25 to 22.47+/-6.70 cm2. Medians differed from 20.03 (range 16.59-28.73) to 23.03 (range 14.14-33.69) cm2 (p = 0.0078, 95% confidence interval [CI] = 0.0075 to 0.0081). Successfully treated patients, however, showed a mean decrease from 20.58+/-3.63 (median 19.87) to 16.36+/-6.46 cm2 (median 18.10) at 1 year (p = 0.0156, 95% CI = 0.0151 to 0.0160). The medians differed significantly between groups (p < 0.05).

CONCLUSIONS

Persistent endoleaks after endovascular aortic aneurysm treatment led to an increase in the diameter of the aneurysm, whereas complete occlusion was associated with a significant decrease in aneurysm diameter.

MRI with mangafodipir trisodium in the detection of pancreatic tumours: comparison with helical CT

The aim was to compare spiral CT and MRI enhanced with mangafodipir trisodium (Mn-DPDP) in the detection and staging of pancreatic lesions. 20 patients with suspected pancreatic cancer were included in a phase III study. Triphasic spiral CT (4 ml s-1) and MRI (axial T1 weighted turbo spin echo with and without fat suppression, T1 weighted gradient echo and T2 weighted turbo spin echo at 1.5 T) were performed. All sequences were repeated following contrast medium using the same instrument settings as in the unenhanced sequences. Mn-DPDP was administered by slow injection of 5 mumol kg-1 body weight. Imaging results were correlated with surgery, laparoscopy, biopsy and/or follow-up. Eight pancreatic adenocarcinomas were present. Ten patients had chronic pancreatitis, and two showed a stenosing papillitis. CT detected eight malignant lesions and MRI detected seven. One pancreatic cancer was not detected with MRI. CT and MRI excluded malignancy in nine patients. MRI and CT returned three false positive results. Mn-DPDP improved delineation of the lesion, resulting in a higher level of diagnostic confidence. Differentiation between pseudotumorous lesions in chronic pancreatitis and pancreatic carcinoma was difficult due to similar slight contrast enhancement. Owing to better delineation of the lesion and the higher confidence in diagnosis, MRI with Mn-DPDP may have the potential to improve the detection rate and the staging accuracy of focal pancreatic lesions. These results need to be confirmed in a larger patient trial.

In vivo imaging of activated microglia using [11C]PK11195 and positron emission tomography in patients after ischemic stroke

Neuroprotective strategies are currently being developed for stroke patients. Although the focus is on the development of early treatment the importance of late pathogenetic events is increasingly recognized. To investigate the microglial reaction in stroke we used a marker for activated microglia, [11C]PK11195, and PET in five patients with ischemic stroke 5-53 days after infarction. In one patient serial measurements were made. We demonstrated in each individual and at each point in time that a microglial reaction takes place in the area where T1 weighted MRI (magnetic resonance imaging) shows intensity changes. We consider this PET method as a promising tool to study the late pathogenetic consequences of cerebral infarction and to evaluate neuroprotective strategies with respect to the consequences of the microglial activation.

Functional cranial neuronavigation. Direct integration of fMRI and PET data

OBJECTIVE

We report our first experiences with the direct integration of fMRI data into cranial neuronavigation.

METHOD

For navigation we used the MKM system and thin-sliced T1 contrast enhanced images. As a first step 21 patients had fMRI for localization of the precentral gyrus, 2 patients for Broca area detection. By anatomical correlation, these functional data were indirectly compared to the intraoperative findings using cortical SSEP (n=20) or cortical stimulation (n=3). Encouraged by these preliminary results, we started the direct integration of fMRI into neuronavigation in June 1999, followed by PET in January 2000, enabling us to compare functional images with intraoperative findings directly. fMRI and PET data were integrated by landmark matching referring on skin fiducials. Meanwhile, fMRI data of 8 patients (6 motorcortex, 2 Broca) and PET images of 1 patient were directly integrated into neuronavigation. Six out of 8 patients had additional cortical monitoring, 2/8 were exclusively operated on by functional neuronavigation.

RESULTS

Using indirect comparison between fMRI and intraoperative findings we observed a good correlation in every case for the motorcortex, but only in 1/2 for the speech area. In all 6 direct integrated fMRI cases, these findings corresponded well to the conventional ones. Both patients with sole functional navigation did not have any postoperative neurological deficit. The inaccuracy of the fMRI ifT1 matching was 2. 7 mm (sigma=0.9 mm) and 1.3 mm (sigma=0.4 mm) of the subsequent referenciation of the navigation. The tumor delinement shown by 11C-methionine PET could be proven by intraoperative biopsy outside its indicated tumor margin. The inaccuracy of the PET matching was 0. 8 mm.

CONCLUSION

Functional neuronavigation enables to visualize and preserve relevant brain areas. Other functional areas like short-term memory, which solely can be detected by fMRI might also be monitored in the future. The integration of PET data expect to gain a better differentiation of tumor and edema.

[Ischemia of the lower extremity due to a persistent a. ischiadica--a possible interventional therapeutic approach]

The sciatic artery is a rarely seen variant of the vessels of the lower limb. Anatomically it is the prolongation of the inferior gluteal artery and accompanies the sciatic nerve from the sciatic foramen to the knee. More than other vessels, the sciatic artery shows vasculopathies like diffuse dilatation or aneurysms. This report describes an interesting case of embolic acute ischemia, caused by a persistent sciatic artery with an aneurysm. We treated the ischemia with intra-a. lysis and bridged the aneurysm with an covered stent.

[Double-helical CT pitfall: the native hyperdense basilar artery]

PURPOSE

The unenhanced signs of basilar thrombosis at computed tomography (CT) is the hyperdense visualization of the basilar artery due to intravascular thrombosis. In patients who are clinically asymptomatic, hyperdense visualization of the basilar artery can be observed, if scanned with a double helical CT. Purpose of the present study was to evaluate the diagnostic significance of these changes seen at double-helical CT.

MATERIAL AND METHOD

Ten patients patients underwent double-helical CT of a portion of the base of the skull. In each case, 5-mm and 10-mm fused slices were obtained. The patency of the visualized vessels was then documented using contrast-enhanced images.

RESULTS

The differences in attenuation between the 5-mm and 10-mm fused slices obtained at native examinations were a median 11 HU. Subsequent contrast enhanced studies documented patency of the examined vessels.

CONCLUSION

The present data show that the hyperdense basilar artery as a sign of thrombotic occlusion is not valid when thin, fused slices are obtained at double-helical CT.

Brain activation during human navigation: gender-different neural networks as substrate of performance

Visuospatial navigation in animals and human subjects is generally studied using maze exploration. We used functional MRI to observe brain activation in male and female subjects as they searched for the way out of a complex, three-dimensional, virtual-reality maze. Navigation activated the medial occipital gyri, lateral and medial parietal regions, posterior cingulate and parahippocampal gyri as well as the right hippocampus proper. Gender-specific group analysis revealed distinct activation of the left hippocampus in males, whereas females consistently recruited right parietal and right prefrontal cortex. Thus we demonstrate a neural substrate of well established human gender differences in spatial-cognition performance.

[Magnetic resonance tomography of the pancreas]

The following publication is an overview looking at the diagnostic possibilities of magnetic resonance imaging regarding diseases of the pancreas and showing image examples. We emphasize new techniques like the MRCP showing meaningful indications and diagnostic limitations.

[Intraarterial chemotherapy in cases of breast cancer]

A general review of the results and technique of intraarterial chemotherapy in cases of breast cancer is given. The remission rate for untreated primary tumors is nearly 100%, for completely treated local relapses approximately 70%. The complication rate is quite low using an intraarterial well-tolerated cytostatic agent such as mitoxantrone. However, thromboembolism of the vertebral artery facing the internal mammary artery may occur. The indication for intraarterial chemotherapy should always be set by an interdisciplinary board.

Foot pain after a plantar fasciotomy: an MR analysis to determine potential causes

PURPOSE

The purpose of this work was to determine potential causes of foot pain in patients who have had a surgical release of the plantar fascia for treatment of fasciitis.

METHOD

We studied 17 patients (15 women, 2 men; age range 22-59 years, mean 40 years) with foot pain after undergoing a fasciotomy. Fourteen unilateral and three bilateral procedures accounted for the 20 ankles evaluated. Mean duration after surgery was 22 months (range 3-53 months). Each patient was instructed to localize the pain to a region of the foot; classify the pain as new onset, persistent, or recurrent; and characterize it as to the action that produced the greatest pain. T1-weighted sagittal and dual-echo T2-weighted images in the sagittal, coronal, and axial planes were obtained in a 1.5 T magnet. The MR studies were evaluated for abnormalities of the plantar fascia, perifascial soft tissues, tendons, and osseous structures.

RESULTS

The plantar fascia appeared thick in all ankles (mean 8.0 mm, range 6-12 mm). A total of 25 symptomatic sites were assessed. An acute plantar fascia rupture explained plantar symptoms in two feet. In another 16 feet (12 with plantar heel pain and 4 with nonspecific heel pain), 6 had documentation of acute plantar fasciitis and 9 demonstrated perifascial edema. Of the latter nine feet, five demonstrated abnormalities of the posterior tibialis, peroneus longus, and peroneus brevis tendons. The pain localized to the medial arch in six feet; five feet had abnormalities of the posterior tibialis tendon and one foot demonstrated edema in the flexor digitorum brevis muscle. The pain localized to the lateral midfoot in one foot, which had a cuboid stress fracture.

CONCLUSION

The cause of foot pain in patients who had a plantar fasciotomy appeared to be multifactorial. Three likely causes of pain were identified: persistent or recurrent acute plantar fasciitis, pathology related to arch instability, and structural failure from overload.

Pediatric liver neoplasms: a radiologic-pathologic correlation

Only 1-2 % of all pediatric tumors occur in the liver. Two thirds of these tumors are malignant and almost all of the tumors cause clinical symptoms due to their mass effects. Besides the poor prognosis in most of the malignant tumors, for further treatment the origin and nature of the neoplasm has to be known. Due to the mostly unimpeded growth into the peritoneal cavity, the origin of the tumors is primarily often unclear and can non-invasively only be determined by advanced imaging techniques. The display of the macro- and microhistological key features of primary pediatric liver neoplasms, including hepatoblastoma (HB), infantile hemangioendothelioma (IHE), mesenchymal hamartoma (MH), undifferentiated (embryonal) sarcoma (UES), and hepatocellular carcinoma (HCC), together with their imaging representation by ultrasound, computed tomography, and magnetic resonance imaging, may deepen the understanding of the underlying pathology and its imaging appearance. Furthermore, in many cases sufficient information may be provided not only to differentiate benign from malignant tumors, but also to guide for adequate treatment.

MR mammography: influence of menstrual cycle on the dynamic contrast enhancement of fibrocystic disease

Magnetic resonance mammography (MRM) provides data regarding the nature of tumours based on contrast medium dynamics; fibrocystic changes in the breast, however, may lead to false-positive results. This study investigated whether the contrast medium dynamics of fibrocystic changes are dependent on the menstrual cycle. Twenty-four patients with palpable lumps but normal mammographies and ultrasound studies were examined. The MRM technique was performed during the first and second part of the menstrual cycle using a FLASH 3D sequence, both native and at 1, 2, 3 and 8 min after intravenous application of 0.15 mmol/kg body weight of gadodiamide. The calculated time-intensity curves were evaluated based on the following criteria: early percentage of contrast medium uptake in relation to the native value; formation of a plateau phenomenon after the second minute; the point of maximal contrast medium uptake; and calculation of the contrast enhancing index. During the second half of the menstrual cycle, a generally greater contrast medium uptake was observed. Nevertheless, when further diagnostic criteria, such as continuous contrast medium increase as a function of time, were considered, there was no increased rate of false-positive findings. The phase of the menstrual cycle may affect the specificity of the examination, if only the quantitative contrast medium uptake and the percentage of contrast medium uptake in the first 2 min are considered. A control MRM during the other half of the cycle may then be indicated and additional diagnostic criteria may improve specificity.

[Temperature stress for patients in routine magnetic resonance examinations]

PURPOSE

To determine energy exposure and temperature changes in routine magnetic resonance imaging practice.

MATERIALS AND METHODS

Body core and skin temperatures were compared in 155 persons (143 patients, 12 volunteers) undergoing routine magnetic resonance examinations with a 1.5 T field-strength magnetic resonance tomography unit using a fluoroptic temperature measurement system.

RESULTS

Average applied energy was 0.3 W/kg for whole body and 1.92 W/kg for spatially localized SAR. The maximum whole-body SAR was 1.43 W/kg spatially localized. Body core temperatures differed from those of the control group by a median 0.1 degree C and only a few patients (16.8%) exceeded the limit (+/- 0.5%) at which regulatory mechanisms set in. All patients remained within the normal physiological circadian temperature range (+/- 1 degree C). Skin temperature rose a median 0.49 degree C, with a maximal increase of 5.31 degrees C, which may be considered to be within the limits of physiological temperature change.

CONCLUSIONS

Clinically relevant warming of the body is unlikely in routine magnetic resonance imaging practice.

[Value of dynamic MRI in the diagnosis of hypophyseal microadenomas]

PURPOSE

To evaluate dynamic MR imaging of the pituitary gland.

MATERIAL AND METHODS

19 patients with suspected mass lesions of the pituitary gland were examined at 1.5 Tesla with dynamic and standard MRI using a Turbo-FLASH sequence (1 image/s for 40 s).

RESULTS

In 13/19 patients microadenomas were detected. One of the 13 microadenomas was detected using dynamic imaging and was not seen on standard MRI. The remaining 12 microadenomas were diagnosed with standard MRI.

CONCLUSION

Dynamic imaging of the pituitary gland is a time-consuming and costly diagnostic technique. If laboratory results suggest the presence of a microadenoma and conventional MRI is unable to localise it, dynamic imaging should be performed.

[MRCP (magnetic resonance cholangiopancreatography)--an assessment of current status]

For the first time, magnetic resonance cholangiopancretography (MRCP) provides images of the biliary and pancreatic ducts based on 3D data similar to those we are used to from endoscopic retrograde cholangiopancreatography (ERCP) and percutaneous transhepatic cholangiography (PTC). Extraordinarily impressing is the fact that no contrast media have to be applied. The following manuscript shows technical basics and the development of this technique from gradient echo sequences to the recent single-shot techniques. Furthermore possibilities and limitations of MRCP will be discussed with respect to certain illnesses.

[MRI of the abdomen combined with enteroclysis in Crohn disease using oral and intravenous Gd-DTPA]

In spite of the improved MR-diagnosis of the abdomen, MRI is not used as a routine method for the diagnosis of inflammatory small bowel disease. The aim of this study was--after optimazation of the bowel opacification--the correlation of the findings obtained with enteroclysis and MRI in patients with known Crohns' disease. 60 patients between 17 and 72 years of age were investigated. First, an enteroclysis was performed in typical manner. The applicated methylcellulosis was blended with positive oral MR contrast media (Magnevist oral, Schering). After enteroclysis, MRI of the abdomen was performed using T1- and T2-weighted breathhold sequences (Flash 2D pre- and postcontrast and TSE) in axial and coronal planes. The length of the affected bowel and the stenosis seen with enteroclysis correlated well with the visible thickening of the small bowel wall and the stenosis seen in MRI. Using MRI, additional findings could be obtained in 28 patients, such as fistulas, abscesses or a hydronephrosis, or a better assessment of the stenosis was possible with MRI, because of the avoidance of overshadowing of the affected bowel loop with MRI. A brilliant MR-tomographic imaging of the small bowel is possible under the condition, that the small bowel contrast is optimal. The main prerequisite is a large filling volume of the small bowel to reach a homogeneous contrast and a good distension of the small bowel lumen.

MRI follow-up of pisiform bone transposition for treatment of lunatomalacia

OBJECTIVE

Transposition of the pisiform bone is an operative treatment for lunatomalacia. The postoperative viability of the transposed pisiform bone is difficult to assess. The purpose of the study was to evaluate the utility of MRI for postoperative assessment of viability of the pisiform and lunate bones.

DESIGN AND PATIENTS

Six patients who underwent transposition of the pisiform for treatment of lunatomalacia, were assessed pre- and postoperatively with conventional radiographs (including tomography), CT and MRI.

RESULTS

Conventional radiographs, conventional tomograms and CT were all useful in demonstrating the location of the transposed pisiform. CT showed the transposed pisiform without superposition. However, neither CT nor conventional techniques provided information regarding viability of the pisiform. In all patients investigated in the first year following surgery, T1-weighted MR images showed high signal intensity in the transposed bones. In all patients investigated after 1 year, the signal intensity decreased to an intermediate level on T1-weighted images. Enhancement following contrast medium administration in the transposed pisiform and the lunate was noted in all patients, indicative of viability.

CONCLUSION

Contrast-enhanced MRI is able to provide important information regarding the viability of the transposed pisiform and the remaining parts of the lunate. Thus, contrast-enhanced MRI provides an improved means of postoperative assessment regarding short-term follow-up following pisiform transposition. In the long-term follow-up conventional radiography and CT may be equal to MRI in showing increasing sclerosis and/or fragmentation.

[Doubtful mammographic findings: the value of negative MR mammography for tumor exclusion]

PURPOSE

To determine whether the addition of MR mammography (MRM) is useful in excluding malignant lesions and how reliable negative MRM findings are.

METHODS

Amongst 694 MRM's, those originally regarded as normal were retrospectively reappraised. 239 female patients were involved. In all these patients there were clinical, sonographic and/or mammographic findings which were not entirely normal but there was no urgent indication for histological clarification. In 46 patients there were, however, histological examinations since the patients themselves insisted on it. In the remaining patients there was clinical, sonographic, mammographic and/or MRM follow-up after 12 to 18 months.

RESULTS

In 95.4% (200/239) a carcinoma could be excluded by means of MRM, in 7 patients a carcinoma in situ and in two patients an invasive carcinoma was demonstrated histologically which had not been demonstrated by MRM. Even in retrospect, no abnormality could be found.

CONCLUSION

Because of the only moderate sensitivity of MRM in the recognition of carcinoma in situ, doubtful lesions which can be localised, should be biopsied by a stereotactic method. In cases where evaluation is difficult on clinical, sonographic and mammographic findings, MRM is of value in excluding tumours, particularly in patients with increased carcinoma risk.

Value of MR mammography in the detection and exclusion of recurrent breast carcinoma

PURPOSE

This is a study of 140 patients undergoing MR mammography (MRM) for evaluation of possible local recurrent disease following breast-conserving surgical treatment of mammary carcinoma. MRI was performed 1-228 months (mean 28.3 months) postoperatively.

METHOD

MRM and interpretation of the dynamic measurements were performed in a standardized manner after positioning the patient in a double breast coil. A GRE sequence (Flash 3D, TE 5 ms, TR 12 ms, FA 25 degrees) was acquired before and 1, 2, 3, and 8 min after intravenous injection of Gd-DTPA in a dose of 0.15 mmol/kg body wt.

RESULTS

Recurrent disease was excluded in 82.8% of cases with MRM. In another 13.6% of patients, MRM was able to reliably detect recurrence of malignancy. In five cases (3.6%), MRM returned false-positive results.

CONCLUSION

MRM is a sensitive method for detecting or excluding recurrence of malignant disease. It remains to be determined whether early detection of recurrent disease can contribute significantly to improving the prognosis in these patients.

MRI of histologically confirmed mammary carcinoma: clinical relevance of diagnostic procedures for detection of multifocal or contralateral secondary carcinoma

PURPOSE

MR mammography (MRM) is a sensitive diagnostic method for the detection of mammary carcinomas. The present study evaluates whether MRM can yield additional relevant data in cases of histologically confirmed mammary carcinoma.

METHOD

Thirty-four patients with histologically confirmed mammary carcinoma were examined at MRM using a T1-weighted GE sequence and a T2-weighted SE sequence. Morphologic criteria and the dynamic contrast medium behavior of the tumors were evaluated.

RESULTS

MRM showed a 100% sensitivity and diagnostic accuracy in the detection of mammary carcinomas. Additionally, three unexpected contralateral carcinomas were discovered. In 26 patients, there was a multifocal or multicentric tumor process. In 24 patients, peritumoral edema was visualized, which corresponded histologically in 21 patients with lymphangiosis and in 3 with an inflammatory peritumoral reaction.

CONCLUSION

Because of its high sensitivity in the diagnosis of multifocal disease and of contralateral carcinomas, MRM would seem to represent a useful addition to preoperative diagnostic procedures. The potential benefit to the patient and its cost efficiency, however, remain to be clarified.

[Mechanically detachable minicoils attached to a wire for superselective embolization]

PURPOSE

Evaluation of clinical usability and effectivity of newly developed, mechanically applicable minicoils attached to a wire for super-selective embolisation.

MATERIAL AND METHODS

The new embolisation coils have been used in 16 patients aged between 28 and 90 years for the following indications: 4 haemorrhages in cases of advanced carcinoma of the cervix, one false aneurysm, 7 traumatic lesions and 4 arteriovenous fistulas. The minicoils are made of platinum and are attached to a guide wire with a connecting hook. Application is via a microcatheter in coaxial technique.

RESULTS

Percutaneous embolisation has been successful in patients. Additional surgery has not been required in any of them. Manipulation of the system is relatively easy and embolisation is made possible under controlled circumstances. In one case a minicoil disappeared into a peripheral vessel, but could be recovered percutaneously.

CONCLUSION

The minicoils allow super-selective embolisation but, for reasons of cost, should be reserved to such vascular regions where the risk of misplacing must be kept at a minimum. Basic experience with embolisation techniques is indispensable for the application of this method.

Percutaneous transluminal rotational atherectomy in the treatment of peripheral vascular disease using a transluminal endatherectomy catheter (TEC): initial results and angiographic follow-Up

PURPOSE

To evaluate the clinical results of percutaneous transluminal rotational atherectomy in the treatment of peripheral vascular disease.

METHODS

Rotational atherectomy was performed in 39 patients aged 39-87 years (mean 66.6 years). A total of 71 lesions (43 stenoses and 28 occlusions) were treated in 40 limbs. Additional balloon angioplasty was required in 54% of lesions. Fifteen patients (37.5%) presented in Fontaine stage II, 10 patients (25%) in Fontaine stage III and 15 patients (37.5%) in Fontaine stage IV. Rotational atherectomy at 750 rpm was carried out over a 0.014-inch guidewire with continuous aspiration into a vacuum bottle. Follow-up angiography and color flow Doppler examinations were performed in 22 patients (23 limbs) after a mean period of 6 months (range 2-14 months).

RESULTS

There was one primary technical failure. In 36 of 40 lesions there was a good angiographic result with residual stenoses in less than 30%. In 70 lesions treated by rotational atherectomy, however, 54% showed residual stenoses of 30%-50% and these cases required additional balloon angioplasty. The mean ankle-brachial index improved significantly (p << 0.001) from 0.49 before the procedure to 1.01 after the procedure. A single distal embolus, related to primary recanalization, occurred and there were two large inguinal hematomas. Cumulative clinical patency after 6 months was 83.8% and cumulative angiographic patency after 6 months was 79.1%.

CONCLUSION

Percutaneous rotational atherectomy is a promising approach for the treatment of chronic peripheral vascular disease. Further prospective, randomized studies are necessary to compare percutaneous transluminal angioplasty with this new technical approach.

[Abdominal arteriovenous and arterio-portal fistulas: etiology, diagnosis, therapeutic possibilities]

PURPOSE

Arterioportal and arteriovenous fistulas (APF, AVF) are rare vascular disorders occurring as a result of congenital vascular malformation, trauma, iatrogenic causes or neoplasms. The clinical spectrum of presentation ranges from symptom-free individuals to patients with severe portal hypertension or congestive heart failure. While the majority of patients have been treated surgically in the past, interventional radiological procedures are being performed with increasing frequency. To prove this trend we reviewed the international literature.

REVIEW

We reviewed the clinical presentation and management of 79 cases reported between 1980 and 1996 in the literature and six own patients.

RESULTS

Review of the literature and our own six cases show that these fistulas can be divided in intrahepatic (n = 49, 75%) and extrahepatic fistulas (n = 20, 25%). The most important causes are trauma (n = 29, 37%), iatrogenic induced by procedures (n = 21, 27%) and congenital vascular malformations (n = 10, 13%). APFs and AVFs can be diagnosed by ultrasound, computed tomography and magnetic resonance imaging. Angiography confirms the diagnosis and in many cases allows definitive interventional radiologic treatment.

CONCLUSION

Management of AVFs and APFs remains a challenge. However, interventional radiologic procedures provide a safe, low-cost, and effective method for treatment. Due to these facts in the last three years we notice an increasing part of interventional procedures for treatment.

Musculoskeletal involvement in cystic echinococcosis: report of eight cases and review of the literature

OBJECTIVE

Our purpose was to describe the morphologic appearance of musculoskeletal lesions in patients with cystic echinococcosis shown by CT and MR imaging.

CONCLUSION

Patients with musculoskeletal lesions of cystic echinococcosis typically have cystic structures in adjacent soft tissues. These cysts morphologically resemble abscesses, with peripheral uptake of contrast medium and variable signal intensities on T1-weighted MR images. The absence of calcifications or endovesicular daughter cysts does not exclude the diagnosis of cystic echinococcosis.