[Hypoxemia 4 month after right-sided pneumonectomy]. / Hypoxämie 4 Monate nach rechtsseitiger Pneumektomie.

A 64-year-old male reported worsening dyspnea four months after right-sided pneumonectomy, due to lung cancer. Platypneu-or-thodeoxie syndrome was suspected due to a decrease in oxygen-saturation while the patient was in upright position. The shift of the right hemidiaphragm and liver caused compression of the right atrium and a shunt over a persistent foramen ovale. The right-to-left shunt was proven during right heart catheter. Interventional closure of the shunt resulted in immediate improvement of arterial oxygenation and a decrease in dyspnea.

Idiopathic osteonecrosis of the scaphoid (Preiser's disease)--MRI gives new insights into etiology and pathology.

OBJECTIVE: To describe the imaging signs of idiopathic osteonecrosis of the scaphoid (Preiser's disease) and to differentiate the findings from scaphoid nonunion. MATERIAL AND METHODS: 10 patients (4 men, 6 women, mean age 36.9 years) with radial-sided wrist pain were identified to suffer from primary osteonecrosis of the scaphoid. Imaging methods included radiograms in all cases, CT imaging in 9 cases, and contrast-enhanced MRI in 7 cases. In CT and MRI, images were also acquired in the sagittal-oblique plane for depicting the scaphoids in the entire longitudinal extension. Follow-up examinations were performed in 5 patients, two of them underwent surgery with pedicled bone grafts. RESULTS: In all patients, both osteosclerosis and lesions of the bone marrow were most intensive at the proximal scaphoid pole. A three-layered architecture was found. The zone of osteonecrosis was located most proximally, followed by a zone of repair in the middle, and the zone of viable bone marrow in the distal part of the scaphoid. In contrast to scaphoid nonunion, pathological fractures were exclusively located within the zone of osteonecrosis in 8 cases. Applying morphologic criteria, three stages of Preiser's disease were discernible. The initial stage (proximal osteosclerosis, but unaltered shape of the scaphoid), the advanced stage (pathologic fractures, volume loss of the proximal pole), and the final stage (osteonecrosis of the entire scaphoid). CONCLUSION: Pathoanatomy of Preiser's disease and the differentiation into three zones of bone marrow viability can be explained with the retrograde blood supply of the scaphoid. In its natural course, three different stages can be depicted with the initial stage seen only in MRI.

[Clinical value of dual source computerized tomography in primary diagnosis of coronary heart disease]. / Klinische Wertigkeit der Dual-Source-Computertomographie (DSCT) in der Primärdiagnostik der koronaren Herzkrankheit.

UNLABELLED: Dual-source-CT-technology (DSCT) improves temporal resolution of cardiac computed tomography to 83 ms per heart-phase. In this study, the clinical performance of this new method is evaluated. MATERIALS AND METHODS: In fifty patients (33 male, 17 female; age 50 +/- 13 years) with suspected coronary heart disease, CT angiography (slice thickness 0.75 mm, contrast-agent 60-80 ml iomeprol) was performed with a Somatom Definition scanner. Based on the coronary 15-segment-model of the AHA, scores for image quality and lumen reduction were established to enable the observer, to give recommendations for further therapy. RESULTS: Out of 750 possible AHA-segments, 655 were depicted (87.3%). 591 segments (90.2%) were assessed without any limitation of quality, 49 (7.5%) segments showed moderate, and 15 (2.3%) segments severe limitation in image quality. 508 (77.6%) segments were without pathological findings, 92 (14.0%) segments had minimal atherosclerotic lesions, 42 (6.4%) segments suffered from stenoses with lumen reduction less than 70%, and 13 (2.0%) showed significant stenoses of more than 70%. In 31 patients (62%), coronary heart disease was ruled out by CT angiography without any need for further non-invasive or invasive diagnostics. 8 patients (16%) underwent stress-testing for ischemia. In 11 (22%) patients coronary angiography was recommended, and DSCT findings were confirmed in 10 cases. Only one LCx stenosis was overestimated in DSCT. CONCLUSION: Contrast-enhanced DSCT is a powerful tool in diagnosis of coronary heart disease. 98% of coronary segments could be assessed in diagnostic quality, and at least 90% of haemodynamically significant coronary stenoses were detected.

[Early radiological diagnostics for scapholunate dissociation (SLD)]. / Radiologische Frühdiagnostik der skapholunären Dissoziation (SLD).

The partial tear of the scapholunate ligament (pre-dynamic stage of SLD) as well as the complete tear (dynamic stage) does not lead to carpal malalignment. However, if the completely ruptured ligament is accompanied by lesions of the extrinsic ligaments, both the scaphoid and the lunate are malaligned already at rest (static stage of SLD). Later, osteoarthritis will develop, beginning in the radioscaphoid compartment, progressing to the midcarpal joint, and ending in a carpal collapse (osteoarthrotic stage of SLD). Dynamic SLD is detectable only in stress views and in cinematography. The high utility of MRI for directly visualizing the injured ligament is emphasized: reparation tissue is focally enhanced at the rupture site by intravenously applied contrast agent; the individual segments of the scapholunate ligament can be visualized in direct MR arthrography, therefore allowing differentiation of partial and complete ligamentous tears.

[Scaphoid fracture and nonunion: current status of radiological diagnostics]. / Skaphoidfraktur und -pseudarthrose: Eine aktuelle Standortbestimmung der radiologischen Diagnostik.

Scaphoid fractures, which involve approximately two-thirds of all wrist injuries, are often not detected during initial radiographic examination. By using high-resolution CT and dedicated MRI, it is possible to recognize scaphoid fractures soon at the first diagnostic approach and to assess fragment stability. CT imaging provides all the relevant information of the fracture extent and of the fracture healing in the follow-up. MRI is most sensitive in the detection of scaphoid fractures; however, fracture signs must be differentiated from those of a bone bruise. Both the initially overseen scaphoid fracture and the unsuccessful healing can lead to the natural history of scaphoid nonunion. In the injured scaphoid, CT imaging is essential for depicting the osseous morphology, whereas contrast-enhanced MRI is crucial for assessing the viability of the proximal fragment.

[Scaphoid fractures--operative or conservative treatment? A CT-based classification]. / Kahnbeinfrakturen--wann operativ, wann konservativ? CT-basierte Klassifikation.

Traditionally acute scaphoid fractures were treated by immobilization. As a consequence we have to deal with a high number of scaphoid non-unions or SNAC wrists. A study of 30 patients with scaphoid non-union showed that only 30% (9 patients) have not seen a doctor, while the majority of the patients (70%, 21 patients) were treated by a physician after trauma. In 15 (71.4%) of these 21 patients a missed diagnosis and in 6 (28.6%) a failed conservative treatment of the scaphoid fracture were the reasons for scaphoid non-union. Therefore, improvements in the diagnosis and therapy of scaphoid fractures are urgently needed. Herbert's classification of scaphoid fractures provides the underlying rationale for treatment according to the fracture type seen on X-ray. Differentiation between stable and unstable fractures sometimes is difficult from conventional X-rays. In these cases we recommend a CT bone scan in the long axis of the scaphoid. According to the CT scan we modified Herbert's classification: undisplaced waist fractures are classified as stable and can be treated conservatively or can be stabilized percutaneously using minimally invasive procedures. Comminuted or displaced fractures are classified as unstable and need operative treatment because of the increased risk of scaphoid non-union after plaster immobilization. Fractures of the proximal pole of the scaphoid should be treated operatively by internal fixation, even if they are not displaced, because of the reduced perfusion. We recommend a CT scan of the scaphoid, if there is any doubt about the diagnosis or the stability of the scaphoid fracture. In any case, a CT scan has to be ordered to justify a conservative treatment.

Comprehensive MR angiography of the lower limbs: a hybrid dual-bolus approach including the pedal arteries.

The purpose of this study was to include the pedal vasculature into the coverage of peripheral multistation magnetic resonance angiography (3DceMRA). A total of 216 patients suffering from peripheral vascular disease were examined with a modified hybrid dual-bolus technique. The cruropedal arteries were acquired first with two sagittal slabs and time-resolved 3D sequences. Then the aortofemoral vessels were visualized using the bolus-chase technique and a second contrast injection. Interventional procedures were performed in 104 patients, and in 69 of those, the cruropedal vessels were also examined with digital subtraction angiography (iaDSA). Using 3DceMRA, the cruropedal arteries were displayed with both excellent and good quality in 95% (205/216 cases), and without any venous overlay in 94% (203/216 cases). The aortofemoral vessels were not jeopardized by the first contrast injection. With iaDSA as the standard of reference, observed sensitivity of 3DceMRA was found in ranges from 80% (29%, 99%) to 100% (86%, 100%) for assessing significant stenoses, and observed specificity ranged between 93% [80%, 98%] and 100% (82%, 100%). In conclusion, hybrid dual-bolus 3DceMRA significantly reduces the limitations of standard single-bolus 3DceMRA in anatomic coverage and temporal resolution of the cruropedal arteries, thus providing high-quality images of the entire peripheral vasculature.

[Differential diagnosis of the signal-compromised lunate in MRI]. / Zur Differenzialdiagnostik des "signalkompromittierten" Os lunatum in der MR-Tomographie.

PURPOSE: To define both the underlying pathology and diagnostic criteria in lunates presenting with conspicuous signal pattern in MRI. MATERIALS AND METHODS: The retrospective evaluation of 2940 MRI examinations revealed 203 patients with signal alterations of the lunate. All MRI examinations were performed on 1.5-Tesla platforms using dedicated surface coils and an intravenous contrast agent. To establish a definitive diagnosis, a total of 252 MRI examinations (49 follow-ups), 22 CT examinations and 4 arthroscopic studies were obtained in addition to the obligatory conventional radiographs. RESULTS: Incorporating all clinical data, radiographs and MRI examinations succeeded in assigning a diagnosis in 136 signal-compromised lunates (67.0 %), whereas additional diagnostic procedures or follow-up examinations were required for the definitive diagnosis in 57 cases (33.0 %). The most frequent entities were 51 cases of Kienbock's disease (25.1 %), 47 cases of ulnolunate-(triquetral) impaction syndromes (23.2 %) and 44 cases of intra-osseous ganglion cysts (21.7 %). Other pathologies included 23 degenerative, 19 traumatic and 10 inflammatory changes as well as 9 congenital conditions. For MRI assessment of the altered lunate, the most important parameters were location and morphology as well as involvement of the articular and osseous structures of the carpus. CONCLUSION: The lunate may be affected by different pathological states of the wrist. In total, only one quarter of the signal-compromised lunate represented Kienboeck's disease.

[Direct MR arthrography of the wrist in comparison with arthroscopy: a prospective study on 125 patients]. / Direkte MR-Arthrographie des Handgelenks im Vergleich zur Arthroskopie: Eine prospektive Studie an 125 Patienten.

OBJECTIVE: In literature the diagnostic value of MRI for detecting lesions of the carpal ligaments and the TFCC is judged controversially. The aim of the following study is to determine the diagnostic accuracy of direct MR arthrography for depicting and staging of intraarticular lesions of the wrist. MATERIAL AND METHODS: One day before undergoing arthroscopy, 125 patients suffering from wrist pain were examined with direct MR arthrography in a prospective and blinded study. A mixture of contrast medium (iodine-containing contrast medium and gadopentetate in relation 200 : 1) was injected into both radiocarpal and midcarpal joints. The following sequences were acquired on a 1.5T scanner: coronal T1-weighted SE, coronal fat-saturated T1-weighted SE, coronal T1-/T2*-DESS-3D, and sagittal T2*-weighted MEDIC. MRI results were compared with arthroscopic findings using statistical analysis (SEN = sensitivity, SPE = specificity, PPV = positive predictive value, NPV = negative predictive value, ACC = accuracy). RESULTS: In comparison to arthroscopy as the accepted diagnostic gold standard, the following results were found for MR arthrography. Detection of TFCC lesions: SEN 97.1 %, SPE 96.4 %, PPV 97.1 %, NPV 96.4 %, ACC 96.8 %. Detection of complete tears of the scapholunate ligament: SEN 91.7 %, SPE 100 %, PPV 100 %, NPV 99.1%, ACC 99.2%. Detection of partial tears: SEN 62.5 %, SPE 100 %, PPV 100 %, NPV 94.8 %, ACC 95.2 %. Detection of cartilage defects: SEN 84.2 %, SPE 96.2 %, PPV 80 %, NPV 97.1 %, ACC 94.4 %. In total, only three lesions of the lunotriquetral ligament were present. CONCLUSION: Direct MR arthrographic imaging is well suited for detecting intraarticular lesions of the wrist. The presented diagnostic results of MR arthrography are superior to the results of unenhanced MRI reported in the literature. Direct MR arthrography as a reliable diagnostic tool is strongly recommended if lesions of the scapholunate ligament and the triangular fibrocartilage complex are suspected. In contrast, an attitude of caution must be adopted in diagnosing lesions of the articular cartilage of the wrist.

[Radiologic diagnosis of lunate necrosis]. / Radiologische Diagnostik der Lunatumnekrose.

In the literature little is to be found concerning diagnosis and differential diagnosis of Kienböck's disease. Because of technical development in radiological imaging, we now possess very detailed pictures. However, there are many radiological findings within the lunate bone, which can be misinterpreted as Kienböck's disease. Pathological findings of the lunate bone are demonstrated, which are not Kienböck's disease. These findings were compared to different stages of Kienböck's disease and identified. The early stages of Kienböck's disease show changes especially in the MRI, which are very similar to acute bone bruise, ulnar impaction syndrome, synovialitis or gout. Vessel tubes or an intraosseous ganglion can be mistaken for Kienböck's disease. In the late stages of Kienböck's disease, it can be difficult to differentiate this from pseudarthrosis of the lunate bone. The differentiation between Kienböck's disease and other pathological findings is at times very difficult--even with MRI. However, sometimes diagnosis can only be verified by MRI. We therefore suggest that Kienböck's disease must be correctly diagnosed with help of the MRI before commencing with any therapeutic steps.

[MR angiography of pelvic and leg arteries: initiation with time-resolved data acquisition of the lower legs]. / MR-Angiographie der Becken-Bein-Arterien: Beginn mit zeitaufgelöster Datenakquisition an den Unterschenkeln.

58 patients suffering from peripheral arterial vascular disease were examined using contrast-enhanced MR angiography with the intention of optimizing the visualization of lower leg arteries. Different from the customary acquisition order, were first the arteries of the lower legs depicted with three time-resolved phases. Afterwards, the iliacal and femoral vessels were imaged by applying the floating-table technique in two steps. In all cases, the lower leg arteries were depicted without overlying veins. By injecting the contrast agent in two phases, imaging quality of the iliofemoral arteries was not significantly reduced.--In conclusion, we would recommend the hybrid technique of peripheral contrast-enhanced MRA with primarily starting the acquisition of the lower legs in cases of foot infections or ulcerations where the transit time is reduced bi- or unilaterally.

[Multi-slice spiral CT of the coronary arteries: clear vascular imaging using standard software]. / Mehrzeilen-Spiral-CT der Koronararterien: Ubersichtliche Gefässdarstellung unter Verwendung einer Standard-Software.

OBJECTIVE: To visualize the coronary arteries with a clear view and over a long distance by using data sets from contrast-enhanced computed tomography of the heart. MATERIAL AND METHODS: Image data of 151 patients suffering from coronary artery disease were calculated by means of retrospective triggering at four different diastolic delay times in contrast-enhanced CT. The large coronary segments were subsequently reconstructed in two planes with multiplanar volume reconstruction (MPVR)--a non-dedicated postprocessing software. RESULTS: On the pre-condition that data sets were acquired at sinus rhythm and at a heart beat rate lower than 65/min coronary arteries could be depicted over a long distance in single or double angulated reconstruction planes with the help of multiplanar volume reconstruction (MPVR). Time consumption for image reconstruction was reasonable. Additionally to the anatomy of the coronary arteries in two different planes, typical CT findings in occluding coronary artery disease are presented. CONCLUSION: Multiplanar volume reconstruction (MPVR) implemented on most workstations is a powerful and ideal postprocessing tool in reconstructing coronary arteries from contrast-enhanced CT data sets.

Experimental basis of shockwave-induced renal trauma in the model of the canine kidney.

Using the new electromagnetic shockwave source of the Modulith SL 20 shockwave-induced renal trauma was evaluated by acute and chronic studies in the the canine kidney model. In a further study the electromagnetic shockwave source of the Lithostar Plus Overhead module was tested. Overall, 92 kidneys were exposed to shock waves coupled either by water bath (Modulith lab type) or by water cushion (Modulith prototype, Lithostar Overhead) under ultrasound localization. The generator voltage ranged between 11 and 21 kV, the number of impulses between 25 and 2500. After application of 1500/2500 shocks the extent of the renal lesion depended strictly on the applied generator voltage and was classified into 4 grades: Grade 0, no macroscopic trauma detectable (at 11-12 kV); grade 1, petechial medullary bleeding (at 13 kV); grade 2, cortical hematoma (at 14-16 kV); and grade 3, perirenal hematoma (17-20 kV). Whereas at low and medium energy levels the number of shocks played only a minor role, at maximal generator voltage (20 kV) even 25 impulses induced a grade 2 and 600 shocks a grade 3 lesion, emphasizing the importance of shockwave limitation in the upper energy range. In shockwave-induced renal trauma a vascular lesion was predominant and cellular necrosis was secondary. Coupling with a water cushion resulted in a 15%-20% decrease in the disintegrative and traumatic effect, which was compensated for by increasing the generator voltage by 2 kV. Long-term studies showed complete restitution following grade 1 and 2 trauma, whereas after a grade 3 lesion a small segmental and capsular fibrosis without hyperplasia of the juxtaglomerular apparatus was observed. Based on the characteristic ultrasound pattern found in the first study, the threshold for induction of grade 1 lesion was investigated. With both lithotripters a wide range for induction of a grade 1 lesion (Modulith 234-411, Lithostar Plus 220-740) and also a significant overlapping with grade 0 and 2 lesions was seen at low energy settings (levels 2-4). In contrast, the range of shocks (Modulith 96-150, Lithostar Plus 90-142) and overlapping was minimal when high energy was used (levels 7-9). Finally, the disintegration-trauma coefficient combining the results obtained in a standard stone model with those of the canine kidney model was introduced.