P1161Pre-implantation MRI identification of late-mechanical activation segments with dedicated software platform to guide the cardiac resynchronization therapy

Introduction

The Cardiac Resynchronization Therapy (CRT) is a well-established treatment for patients with electromechanical dyssynchrony of the left ventricle (LV) and drug-refractory heart failure (HF). Despite technical improvement and accurate selection, still a 30% of implanted patients are non-responder to CRT. Suboptimal LV lead placement in areas of early mechanical activation is one of the major reasons of poor response rate.

Objectives

To evaluate and test the performance of an integrated and highly automated software platform used for processing and analyzing standard preoperative Cardiac Magnetic Resonance (CMR) data and overlaying this data with real-time fluoroscopic images. 

Methods

Using a dedicated software for post-hoc analysis of CMR data, segments of late mechanical activation (LMA) in the 16 segments model before CRT implant were identified and used as target segments for the coronary sinus (CS) lead implant. All patients underwent CRT implantation after performing a standard CMR. A real time match between the selected segments and the fluoroscopic images (AP and at least one LAO or RAO projection with ≥30° angle difference) was obtained for each case during the procedure (Figure 1). In two patients who underwent to Cardiac-CT (CCT), a postprocessing analysis with a dedicated software was performed to obtain a 3D CS anatomy model before implant, which was used as a guide for the CS catheter during procedure. The 3D CS model was merged with the 3D-LV Model. Patients were enrolled during a period from 30th November 2017 to 30th July 2019 and where divided in two groups, Group A if the CS lead was placed in the target segment and Group B if the lead didn´t reach the target.

Results

Considering all patients (21 patients, 24% females and 76% males, age 69 ± 10.7 years; NYHA class: 3 ± 0.4; 62% with Late-gadolinium-enhancement and 38% without Late-gadolinium-enhancement; EF 30 ± 5.6%; QRS 174.9 ± 29 ms; 81% with left bundle block), in 57% the placement of the CS lead to the pre-procedurally defined LMA target segments and an effective pacing was obtained. In the Group A we documented a trend in shorter paced QRS duration (QRS pre 173.2 ± 31.9, QRS post 138.3 ± 26) and a trend in EF increase during short-term follow up (EF from 29.4 ± 3% to 41.9 ± 3%) compared with Group B (QRS pre 177.2 ± 26, QRS post 147 ± 33.6 and EF from 36 ± 7.5% to 41 ± 5%).

Conclusions

The pre-implantation planning of CRT implant, in patients candidate to a resynchronization treatment, focusing on identification of the LMA segments, is an emerging tool. Real-time fluoroscopic images and CMR-guided LV CS lead placement provide preferential sites for lead placement and preliminary data demonstrated a trend in increase of treatment response. A successful implant in the preselected target segment was achieved in 57% of cases in our study and a trend in a concomitant better electrical response of resynchronization was observed.

Abstract Figure 1. CS lead in target segments

Noninvasive Assessment of Renal Artery Stenosis

The purpose of this study was to evaluate MR angiography (MRA) and color Doppler sonography as noninvasive screening methods in suspected renovascular hypertension. Fifty-five consecutive patients with arterial hypertension were examined prospectively using high resolution 3-D TOF MRA and color Doppler sonography. Intraarterial angiography was the standard of reference. Stenoses of 60% or more were regarded as significant. MR angiograms were evaluated by 3 independent observers who studied 110 main renal arteries. All 8 significant stenoses and 2 occlusions were correctly classified with MRA while one 60% stenosis was underestimated by color Doppler sonography. Mild stenoses were overestimated by MRA in 4 and by color Doppler sonography in 6 cases. A drawback of both methods was the large number of not evaluable arteries (6 in MRA, 11 in color Doppler sonography). These arteries were regarded as pathologic because stenosis could not be excluded. Due to this fact specificities of MRA and color Doppler sonography were 90% and 85% respectively. Accessory vessels were detected in 47% (8/17) by MRA and in 0% (0/17) by color Doppler sonography.

Spinal metastases from renal cell carcinoma: effect of preoperative particle embolization on intraoperative blood loss

BACKGROUND AND PURPOSE

Surgical repair of spinal metastases from renal origin is often complicated by excessive bleeding. The purpose of this study was to assess the effect of preoperative particulate embolization on intraoperative blood loss.

METHODS

Twenty spinal metastases from renal origin (17 patients) treated by preoperative embolization with polyvinyl alcohol particles were analyzed retrospectively. Surgical decompression was performed within 2 days after embolization. A control group of 10 patients with 11 spinal metastases of renal origin underwent surgery without embolization. The effect of preoperative embolization, of completeness of embolization, and of particle size on the estimated intraoperative blood loss was analyzed using nonparametric statistical tests.

RESULTS

Complete embolization was achieved in 10 cases and partial embolization in the other 10. The estimated blood loss of 19 embolized and 11 control cases was available from the surgical report. Median intraoperative blood loss in 19 embolized lesions was 1500 mL (range, 300-8000 mL), compared with 5000 mL (range, 1440-15000 mL) in the control group. Even after partial embolization, blood loss (median, 2000 mL) was significantly lower than in the control group. No significant differences in estimated blood loss were noted between the use of particles smaller than 250 microm and those larger than 250 microm. No embolization-related permanent neurologic deficit or skin or muscle necrosis occurred.

CONCLUSION

Preoperative embolization of spinal metastases of renal origin with polyvinyl alcohol particles is safe and might reduce intraoperative blood loss significantly. Even partial embolization seems to be effective.

[Possibilities and limits of interventional therapy in necrotizing pancreatitis]

We present a new technique for minimal invasive radiological assisted necrosectomy (MIRAN) for infected necrosis in acute pancreatitis. We describe how to place volumic catheters for fragmentation and extraction of necrotic material. In addition a new technique is described for minimal invasive occlusion of selected pancreas tail to avoid fistulas. In 26 patients with infected necrosis of the pancreatic region, 12 patients (46.2%) could be healed by MIRAN alone. 5 patients (19.2%) could be satisfactory treated with a combination of MIRAN and operative necrosectomy. 9 patients (34.6%) died, 5 of them postoperatively. In 7 cases death followed multiple organ failure/dysfunction syndrome. 12 (71%) of 17 patients with the aim of curative treatment could be satisfactory treated with MIRAN. 2 other patients (12%) received additional surgery, 3 patients died (17%), 2 of them without any other treatment. The advantages of MIRAN are reduced trauma, general anaesthesia is not necessary, no difficult surgical preparation is necessary, no limits for additional therapy, reduced damage of neighbouring organs and vital pancreatic tissue as well as avoiding splenectomy.

Digital radiography of the skeleton using a large-area detector based on amorphous silicon technology: image quality and potential for dose reduction in comparison with screen-film radiography

AIM

The purpose of this study was to evaluate a large-area, flat-panel X-ray detector (FD), based on caesium-iodide (CsI) and amorphous silicon (a-Si) with respect to skeletal radiography. Conventional images were compared with digital radiographs using identical and reduced radiation doses.

MATERIALS AND METHODS

Thirty consecutive patients were studied prospectively using conventional screen-film radiography (SFR; detector dose 2.5 microGy). Digital images were taken from the same patients with detector doses of 2.5, 1.25 and 0.625 microGy, respectively. The active-matrix detector had a panel size of 43 x 43 cm, a matrix of 3 x 3K, and a pixel size of 143 microm. All hard copies were presented in a random order to eight independent observers, who rated image quality according to subjective quality criteria. Results were assessed for significance using the Student's t -test (confidence level 95%).

RESULTS

A statistically significant preference for digital over conventional images was revealed for all quality criteria, except for over-exposure (detector dose 2.5 microGy). Digital images with a 50% dose showed a small, statistically not significant, inferiority compared with SFR. The FD-technique was significantly inferior to SFR at 75% dose reduction regarding bone cortex and trabecula, contrast and overall impression. No statistically significant differences were found with regard to over- and under-exposure and soft tissue presentation.

CONCLUSION

Amorphous silicon-based digital radiography yields good image quality. The potential for dose reduction depends on the clinical query.

Chest radiography with a large-area detector based on cesium-iodide/amorphous-silicon technology: image quality and dose requirement in comparison with an asymmetric screen-film system

The purpose of this study was to evaluate a large-area, flat-panel X-ray detector, which uses cesium-iodide (CsI) and amorphous silicon (a-Si). Conventional images were compared with digital images acquired with equal dose (2.5 microGy) and with 50% dose reduction. Fifteen consecutive patients were studied prospectively using an asymmetric screen-film system (detector dose, 2.5 microGy). Digital images were taken from the same patients in a posteroanterior view with detector doses of 2.5 and 1.25 microGy, respectively. The CsI/a-Si active-matrix imager had a panel-size of 43 x 43 cm, a matrix of 3 x 3k, and a pixel-pitch of 143 microm. Hard copies were presented in a random order to eight independent observers, who rated image quality according to six subjective quality criteria. Statistical significance of differences was evaluated with Student's t test for paired samples (confidence level, 95%). Digital radiographs with 2.5 and 1.25 microGy were superior to conventional images regarding all quality criteria. Statistically significant differences were observed for five of six criteria at a detector dose of 2.5 microGy and for only one quality feature at 1.25 microGy. Flat-panel digital imagers based on CsI/a-Si technique have the potential to replace conventional systems and might allow a reduction of radiation dose by 50% without loss of image quality.

[Intraabdominal abscesses. Intervention versus surgical treatment]

As the diagnosis of intraabdominal abscesses has been continuously facilitated by the use of ultrasound and CT-scan, interventional management by percutaneous drainage provides an excellent alternative treatment concept to conventional open surgery. With the use of special flow-suction-catheters which are placed into the abdomen under sonographic or computertomographic guidance, the success rates in the literature are ranging between 33% and 100%, depending on the initial situation, etiology and morphology of the findings. Studies performed with comparable patient collectives showed that interventional treatment methods had equal results to conventional surgery. Under favorable conditions such as in lesions situated in the periphery of the abdomen, with uncomplicated access ways through the abdominal wall and with an etiology of postoperative complications without a primary intraabdominal disease, with homogenous fluid collections in undivided or communicating spaces, the success rates can be raised to above 80%. A close cooperation between radiologists and surgeons in indication, conduct and course of treatment is indispensible for a successful application of these well tolerable interventional treatment concepts.

[Transfemoral pelvic vein angiography with CO2: experiences with pressure- and volume-controlled injections]

PURPOSE

To evaluate the efficacy of CO2 in aortobifemoral DSA with a pressure- and volume-controlled injector.

MATERIALS AND METHODS

In an intraindividual prospective study, 42 patients with arterial occlusive disease underwent stepwise aortobifemoral DSA with CO2 and with iopromid 300.

RESULTS

With Co2, diagnostic images were obtained in 74% of the iliac, 98% of the femoral, 89% of the popliteal arteries, but in only 36% of the arteries of the lower leg. 73% of the stenoses were correctly identified. With therapeutic relevance 8% of the stenoses were overestimated. The length of 1 of 53 occlusions was overestimated and 3 occlusions were simulated. No stenoses or occlusion was missed. There were no severe side-effects. The injector proved to be safe and easy to handle. Fragmentation of the CO2 bolus could be compensated by postprocessing with a minimum opacification summation mode.

CONCLUSIONS

With the equipment used, CO2 was a safe alternative to iodinated CM in routine stepwise aortobifemoral DSA of the iliac, femoral, and popliteal arteries. Because of the risk of overestimation, occlusions and high grade stenoses should be verified with selective injections or iodinated CM before PTA or operations.

Temporary Strecker stent for management of acute dissection in popliteal and crural arteries

Stent placement is a widely used bail-out treatment for dissection of peripheral arteries. Below the level of the superficial femoral artery permanent stenting is complicated by a high incidence of subacute thrombosis and restenosis. We present two cases of arterial occlusion due to acute iatrogenic dissection of the popliteal and distal fibular arteries. Successful treatment was achieved with a new bail-out procedure. Strecker stents were implanted to seal off the dissection flap. Stents were retrieved easily after 24 hr using a myocardial biopsy forceps. After stent retrieval the temporarily stented segments were patent and showed a larger lumen compared with segments treated by balloon dilatation alone. Temporary stenting is a simple and safe procedure and offers the advantage of tacking up dissection membranes and preventing recoil. Persistent presence of a metallic implant as a source of continued injury and stimulus for intimal proliferation is avoided.

[Digital flat image detector technique based on cesium iodide and amorphous silicon: experimental studies and initial clinical results]

PURPOSE

Experimental and clinical evaluation of a digital flat-panel X-ray system based on cesium iodide (CsI) and amorphous silicon (a-Si).

METHODS

Performance of a prototype detector was compared with conventional screen-film radiography (SFR) using several phantom studies. Foreign bodies, fractures, osteolyses, and pulmonary lesions were analyzed. Additionally, 120 patients were studied prospectively, resulting in 400 comparative X-ray studies. The flat-panel detector was exposed with standard dose and with a dose reduction of up to 75%. Detector size was 15 x 15 cm, pixel matrix was 1 x 1 k with a pixel size of 143 microns. Modulation-transfer function was determined to be 18% at the maximum spatial resolution of 3.5 lp/mm.

RESULTS

The diagnostic results achieved with the digital detector were similar to those of conventional SFR, even at reduced radiation exposure. A potential for dose reduction was observed: 50% with respect to osteoarthrosis and fractures, and 75% for determining bony alignment.

DISCUSSION

This new technology can be used in thoracic and skeletal radiography. A significant dose reduction is possible, depending on the suspected disease.

Ischiogluteal bursitis mimicking soft-tissue metastasis from a renal cell carcinoma

We report a case of ischiogluteal bursitis mimicking a soft-tissue metastasis from a renal cell carcinoma. A 66-year-old woman suffered from pain over the left buttock 6 months after she was operated on for renal cell carcinoma of the left kidney. CT of the abdomen and pelvis revealed a tumor-like lesion adjacent to the left os ischii, which was suspected to be a soft-tissue metastasis. Percutaneous biopsy revealed no evidence of malignancy, but the histopathological diagnosis of chronic bursitis.

[Radiologic implantation of central venous portal systems in the forearm]

PURPOSE

To assess the safety and effectiveness of fluoroscopic guided brachial implanted central-venous miniport systems.

PATIENTS AND METHODS

In 32 oncological patients a central-venous miniport system (Vital-Port, CPC-Cook) was implanted in the forearm. The group included 15 women and 17 men (range 33-78, mean 56 years).

RESULTS

Technical success was 100%, in 6 patients vasospasm produced difficulties in catheter placement. In a total of 2878 patients days (range 3-445, mean 90 days) 5 complications occurred (15.6%, 1.7 on 1,000 catheterdays): In one patient (3.13%, 0.35/ 1000 d) the system was changed due to leakage of the catheter near the chamber. Four patients had minor complications: in one case excision of a suture line granuloma was necessary, one haematoma at the site of the chamber was treated with dressing, one patient had a wound dehiscence and one occluded catheter returned to patency by flushing the system with contrast material. Venous thrombosis, phlebitis, catheter dislocation, paravasation or system-related infection did not occur.

CONCLUSION

Fluoroscopic guided peripheral central-venous port implantation is a safe and easy procedure with a high success rate and a low complication rate which can be performed in an outpatient setting.

Clinical application of a flat-panel X-ray detector based on amorphous silicon technology: image quality and potential for radiation dose reduction in skeletal radiography

OBJECTIVE

The purpose of this study was to compare images obtained with a self-scanning, flat-panel X-ray detector based on amorphous silicon technology with conventional screen-film radiographs and to evaluate the possibility of radiation dose reduction in skeletal radiography.

SUBJECTS AND METHODS

One hundred twenty patients were examined prospectively using a conventional screen-film system (speed, 400; detector dose, 2.5 microGy) and a prototype digital amorphous silicon detector (simulated speed, 400 and 800, n = 120; simulated speed, 1600, n = 40). The resulting 400 images were evaluated independently by six radiologists using a subjective five-point preference scale that rated overexposure, underexposure, contrast resolution, spatial resolution, and soft-tissue presentation. Image quality was ranked on a scale from 0 to 10 according to subjective criteria. Statistical significance of differences was determined using Student's t test and confidence intervals (95% confidence level).

RESULTS

Comparison of conventional radiographs with digital images revealed a statistically significant preference for the digital system for soft-tissue presentation (speed 400 and 800) and visualization of osteoarthrotic changes (speed 400). A small but statistically significant preference for conventional images was found with respect to contrast and spatial resolution when digital speed was 800 or 1600; and the visibility of arthrosis at digital speed 1600, osteolysis at digital speed 800 and 1600, and fractures at digital speed 1600.

CONCLUSION

The amorphous silicon-based system with a simulated speed of 400 provided images equivalent to screen-film radiographs. For clinical tasks such as routine follow-up studies, assessment of instability, or orthopedic measurements, a radiation dose reduction of up to 75% may be possible.

Dedicated head-neck coil in MR angiography of the supra-aortic arteries from the aortic arch to the circle of Willis

PURPOSE

To evaluate the usefulness of a dedicated head-neck coil in preoperative imaging of the supra-aortic arteries.

MATERIAL AND METHODS

Forty consecutive patients with suspected carotid artery stenosis underwent MR angiography (MRA). Using a dedicated head-neck coil, we made a complete evaluation of the supra-aortic arteries and graded the internal carotid artery (ICA) stenoses. MRA was performed at 1.5 T with: coronal 3D FISP from the aortic arch to the circle of Willis; transverse 2D FLASH and 3D TONE of the carotid bifurcation; transverse 3D TONE of the carotid siphon and the circle of Willis; and transverse 3D FISP of the aortic arch. I.a. digital subtraction angiography (DSA) was used as the reference. ICA stenoses of 70% and more at DSA (NASCET methodology) were regarded as severe.

RESULTS

Severe ICA stenoses were detected with high sensitivity and specificity: 93% and 92% respectively for coronal 3D FISP; 90% and 85% respectively for transverse 2D FLASH; and 97% and 94% respectively for transverse 3D TONE. The carotid siphon and the intracranial ICA were best depicted by 3D TONE. None of the applied sequences gave a satisfactory visualization of the aortic arch or of the origins of the vertebral arteries.

CONCLUSION

With the head-neck coil, the supra-aortic arteries (including the intracranial vessels) were visualized without the need to reposition the patient, but depiction of the aortic arch was not acceptable. The quantification of ICA stenoses was reliable.

Amorphous silicon, flat-panel, x-ray detector versus screen-film radiography: effect of dose reduction on the detectability of cortical bone defects and fractures

RATIONALE AND OBJECTIVES

The purpose of this phantom study was to assess the diagnostic performance of a self-scanning, solid-state amorphous silicon (a-Si) detector in skeletal radiography using different exposure parameters.

METHODS

A flat-panel detector (15 cm x 15 cm), based on a-Si technology with 143 microm x 143 microm pixel size, 1k x 1k matrix, and 12 bit digital output was used. State-of-the-art screen-film radiography (SFR; speed 400, detector dose 2.5 microGy) was compared with a-Si images taken at doses that were equivalent to a speed of 400, 800, 1,250, and 1,600, respectively. A total of 232 segments of long tubular deer-bones (femur, tibia, humerus, radius) had 110 artificial fractures and 112 cortical defects simulating osteolytic lesions. Receiver operating characteristic analysis was performed for 9,280 observations made by four independent observers. Two-tailed Student's paired t test was used for statistical analysis (95% confidence level).

RESULTS

Receiver operating characteristic analysis yielded equivalent results of the a-Si and SFR system. Even at the lowest dose there were no statistically significant differences between both imaging modalities with respect to the detectability of fractures and cortical defects.

CONCLUSIONS

The results of this study indicate that a-Si detector technology holds promise in terms of dose reduction in skeletal radiography without loss of diagnostic accuracy.

Diagnosis of liver metastases from colorectal adenocarcinoma. Comparison of spiral-CTAP combined with intravenous contrast-enhanced spiral-CT and SPIO-enhanced MR combined with plain MR imaging

PURPOSE

The purpose of this study was to determine whether MR with and without SPIO (AMI-25) could replace spiral-CTAP in the staging of colorectal adenocarcinoma.

MATERIAL AND METHODS

Thirty-five patients were studied prospectively by means of i.v. contrast-enhanced spiral-CT, spiral-CTAP, and MR of the liver. MR imaging was performed before and after infusion of AMI-25. Diagnoses were compared to intraoperative findings (n = 35) which included intraoperative ultrasound (n = 21), and follow-up CT (n = 18).

RESULTS AND CONCLUSION

Fifteen patients were found to have a total number of 53 liver metastases and 43 benign lesions were detected. Evaluation was performed in four different ways: 1) i.v. contrast-enhanced spiral-CT; 2) i.v. contrast-enhanced spiral-CT + spiral-CTAP; 3) plain MR; 4) plain MR + SPIO-enhanced MR. I.v. contrast-enhanced spiral-CT, spiral-CTAP and SPIO-enhanced MR identified patients with liver metastases with equal sensitivity. However, owing to its significantly higher sensitivity, based on a lesion-by-lesion analysis, spiral-CTAP cannot be replaced by SPIO-enhanced MR in patients who are to undergo liver resection. A limitation in spiral-CTAP is its relatively low specificity.

[Computer tomography-guided gastrostomy, jejunostomy and gastrojejunostomy. A reliable non-surgical method also for contraindications and failure of percutaneous endoscopic gastrostomy]

OBJECTIVE

To analyse retrospectively the results of CT (computed tomography)-guided gastrostomy or gastroenterostomy where an endoscopic procedure was not possible or had failed.

PATIENTS AND METHODS

Between August 1993 and March 1997, CT-guided gastrostomy (n = 50) or gastroenterostomy (n = 8) was performed in 58 patients (mean age 56 +/- 6 years; 51 males, 7 females). An endoscopic or fluoroscopic method had been contraindicated in 52 and had failed in 6 patients.

RESULTS

Technical success was achieved in all patients. Three patients needed intravenous sedation. There were no procedure related complications requiring treatment. Three patients had a mild infection at the site of the skin puncture.

CONCLUSION

CT-guided gastrostomy or gastroenterostomy is a safe and simple procedure which provides a minimally invasive alternative also in patients with contraindications to the established percutaneous method.

Cerebral CT angiography in the diagnosis of acute subarachnoid hemorrhage

PURPOSE

To evaluate the usefulness of CT angiography (CTA) in the detection of intracranial aneurysms in patients with acute subarachnoid hemorrhage (SAH).

MATERIAL AND METHODS

In 53 patients with nontraumatic SAH a helical contrast-enhanced CTA was performed. CTA data were reconstructed with maximum intensity projection (MIP). Each patient underwent selective arteriography of the cerebral vessels (as the gold standard). CTA (axial images and MIP reconstructions) and arteriography were evaluated separately and their diagnostic information was compared.

RESULTS

In 14 of the 53 patients neither CTA nor angiography showed a vascular malformation. In the remaining 39 patients, angiography demonstrated a total of 51 aneurysms ranging in size from 3 mm to 16 mm. CTA missed one of these aneurysms, which was located at the internal carotid artery. 3-D CT reconstruction was slightly superior to arteriography in the demonstration of the neck, shape and direction of the aneurysms. Partial thrombosis of 3 aneurysms was demonstrated only by CTA.

CONCLUSION

Although CTA cannot replace cerebral arteriography in the diagnostic work-up of acute SAH, it proved to be helpful in demonstrating the topographic anatomy of cerebral aneurysms and surrounding structures.

Spontaneous rupture of liver in a patient with Ehlers Danlos disease type IV

Ehlers-Danlos syndrome (EDS) type IV is an autosomal dominant connective tissue disease caused by mutations in the type III collagen gene resulting in extreme tissue fragility. Affected individuals are at risk of dramatic and often fatal complications, mostly spontaneous arterial, uterine, or colonic ruptures. Phenotypic expression of EDS type IV is variable and clinical signs are generally quite subtle, thus making a prompt diagnosis difficult. The case of a 33-year-old woman is described who presented with a wide range of clinical features and sequelae that eventually led to the diagnosis of EDS type IV. She presented with spontaneous liver rupture, renal infarction, and pneumothorax, all representing rare complications of EDS type IV. Prior history revealed a uterine rupture in advanced pregnancy associated with ischemic necrosis of the descending and sigmoid colon. EDS type IV should be suspected in young individuals who present with such unusual complications. Early diagnosis is essential if severe or even lethal complications are to be avoided in the diagnostic and therapeutic management of such patients.

Flat-panel x-ray detector using amorphous silicon technology. Reduced radiation dose for the detection of foreign bodies

RATIONALE AND OBJECTIVES

The authors evaluate a new flat-panel x-ray detector (FD) with respect to foreign body detection and reduction of radiation dose compared with screen-film radiography.

METHODS

Flat-panel x-ray detector is based on amorphous silicon technology and uses a 1 k x 1 k photo-detector matrix with a pixel size of 143 x 143 microns and 12-bit digital output. A thallium-dotted cesium iodide scintillation layer converts x-rays into light. An ex vivo experimental model was used to determine the detectability of foreign bodies. Foreign bodies with varying sizes were examined: glass with and without addition of lead, bone, aluminium, iron, copper, gravel fragments, and graphite. Four hundred observation fields were examined using conventional radiography (speed, 400; system dose: 2.5 microGy) as well as FD with a simulated speed of 400, 800, 1200, and 1600, corresponding to a detector dose of 2.5 microGy, 1.25 microGy, 0.87 microGy, and 0.625 microGy, respectively. Four independent radiologists performed receiver operating characteristic analysis of 8000 observations.

RESULTS

Flat-panel x-ray detector with a simulated speed of 400 was significantly superior (P = 0.012) to screen-film radiography (speed, 400). At a simulated speed of 800 and 1200 FD yielded results equivalent to screen-film radiography. Flat-panel x-ray detector was significantly inferior to screen-film radiography at a simulated speed of 1600 (P = 0.012).

CONCLUSIONS

Flat-panel x-ray detector technology allows significant reduction in radiation dose compared with screen-film radiography without loss of diagnostic accuracy.

Magnetic resonance of the disk of the temporomandibular joint. MR imaging protocol

Disk displacement can be well detected using proton density-weighted and T2*-weighted two-dimensional gradient-echo sequences. In uncertain cases, especially if the bilaminar zone is not sufficiently represented, a contrast-enhanced T1-weighted spin-echo sequence should also be performed. Also in patients with disk degeneration and osteoarthritis of the temporomandibular joint, proton density-weighted and T2*-weighted two-dimensional gradient-echo sequences are of great diagnostic value. In this collective, however, T1-weighted contrast-enhanced spin-echo sequences should be generally performed, to demonstrate inflammatory reaction of the synovia.

[CT-guided percutaneous endoscopic gastrostomy: a successful method if transillumination is not possible]

BACKGROUND AND OBJECTIVE

If transillumination is not possible, percutaneous endoscopic gastrostomy (PEG) is contraindicated. In these cases the stomach had so far to be punctured directly during radiological monitoring. A new method is described which combines endoscopy and computed tomography (CT) for performing a percutaneous endoscopic gastrostomy.

PATIENTS AND METHODS

Among 189 patients who were to have the procedure there were eleven (nine men, two women) in whom transillumination was not possible. After endoscopic insufflation of air PEG was done under CT guidance, using the common pull-through technique.

RESULTS

The combined method was successful in ten of the eleven patients without complication. In one patient with hepatomegaly and interposition of the transverse colon PEG was not possible even with CT guidance.

CONCLUSIONS

The combined endoscopic-radiological method is practicable and safe in cases in which transillumination is not possible. There are several advantages compared with direct puncturing: The common pull-through technique can be used; radiological exposure is low and other clinically relevant findings may be revealed by the endoscopy.

[Asymptomatic choledochal cyst]

HISTORY AND FINDINGS

A 45-year-old woman sustained an ankle fracture in an accident. At examination she was found to have marked pallor of skin and mucosae. There was no hint for melaena or haematemesis.

INVESTIGATIONS

Biochemical tests showed marked iron deficiency anaemia (haemoglobin 7.5 g/dl) and raised serum bilirubin and C-reactive protein levels (1.94 mg/dl and 85.2 mg/l, respectively). Abdominal sonography revealed a cystic space-occupying mass (8 x 4.5 cm) projecting onto the gallbladder, interpreted as a choledochal cyst of unknown origins without bleeding. After treatment of the ankle fracture an endoscopic retrograde cholangiopancreatography was performed. This showed a large cyst of the choledochal duct into which the cystic and choledochal ducts entered, without evidence of tumour or haematoma. There was also a 1 cm prepapillary common choledochal and Wirsung duct.

TREATMENT AND COURSE

With these findings, the diagnosis of a congenital choledochal cyst (type Ia of Todani) could be made. After healing of the ankle fracture the cyst was removed and a Roux Y-anastomosis created. The cystic tissue was benign. At follow-up 6 months later the patient was symptom-free and no longer anaemic.

CONCLUSIONS

Congenital choledochal cysts are very rare in Europeans. The symptom-free course with anaemia and no manifestation until adulthood is also very unusual.

[Contrast medium administration in spiral computed tomography: the results of a consensus conference. Institute for Radiodiagnosis, Regensburg]

The rapidity of spiral (helical-) computed tomography requires new protocols for i.v. contrast media administration. Flow rate, volume and delay are discussed controversially in the literature. Hence, a consensus meeting was initiated. In this meeting, problem related questions were designed, discussed and answered using a digital vote system. Spiral-CT-technology was found to be the ideal examination technique for thorax, liver, pancreas, kidney and the retroperitoneal space with an overall agreement between 89 and 97%. The exclusive use of nonionic contrast media and power injectors was recommended by 100% of the participants. More than 90% of the contributors did not accept native scans only for examinations of the neck, thorax, liver, pancreas, kidney and the retroperitoneal space. Regarding volume, flow rate, delay and physical CT-parameters the agreement laid between 50 and 100%. The meeting concluded that randomised controlled studies should be performed to evaluate detailed contrast media protocols for helical CT.

Three-dimensional MP-RAGE--an alternative to conventional three-dimensional FLASH sequences for the diagnosis of viscerocranial tumours?

Imaging with three-dimensional (3D) sequences is a frequently used magnetic resonance (MR) technique in the assessment of ear, nose and throat (ENT) tumours near the skull base. Few reports on the contrast behaviour of 3D magnetization prepared rapid gradient echo (MP-RAGE) sequences and their application in ENT tumours exist in the published literature. This paper discusses whether 3D MP-RAGE is an alternative to conventional 3D gradient echo (3D GE) sequences for the diagnostic evaluation of the visceral cranum. Measurements were performed with a Magnetom SP 63 MR system (Siemens) at 1.5 T. 10 healthy volunteers were examined using 3D FLASH sequences with varied flip angles (90 degrees, 70 degrees, 40 degrees, 20 degrees, 10 degrees) and using 3D MP-RAGE to optimize the signal-to-noise ratio (SNR) of muscle, fat and gland tissue. After this optimization 25 patients with ENT tumours near the skull base were examined with 3D FLASH 40 degrees, 3D MP-RAGE 10 degrees (both before and after application of contrast medium) and with 3D FISP 70 degrees (without contrast medium). SNR and contrast-to-noise ratio (CNR) of tumour, inflammatory disease, brain (white and grey matter), compact bone, fat and muscle were calculated. The advantages of 3D MP-RAGE over 3D FLASH 40 degrees include decreased imaging time with decreased motion artifacts and a relatively high contrast between tumour and surrounding tissues. The tissue contrast yielded by the T1/T2* weighted 3D gradient echo sequence FISP with a flip angle of 70 degrees was not as good as that yielded by 3D MP-RAGE with and without contrast together. In conclusion a combination of contrast enhanced and unenhanced 3D MP-RAGE sequences is the technique of choice for the examination of ENT tumours near the base of the skull.

Renal arteries: evaluation with optimized 2D and 3D time-of-flight MR angiography

PURPOSE

To compare two-dimensional (2D) and three-dimensional (3D) time-of-flight (TOF) techniques in magnetic resonance (MR) angiography of renal arteries.

MATERIALS AND METHODS

In 46 patients, MR angiography was performed with 3D tilted optimized non-saturating excitation (TONE), 3D fast imaging with steady precession (FISP), and 2D fast low-angle shot (FLASH) during breath holding. Intraarterial angiography was used as a reference. MR angiograms were evaluated for stenoses, length of renal arteries, accessory arteries, venous overlap, and image quality.

RESULTS

The 3D TONE sequence was best for detection of severe stenoses (sensitivity, 100%; specificity, 89%), delineation of accessory arteries, and image quality. Overlap of renal veins was the most important disadvantage of 2D FLASH. Decreased saturation effects, however, can be advantageous in 2D TOF imaging.

CONCLUSION

Use of the 3D TONE sequence provided improved image quality and diagnostic value compared with 3D FISP technique. The 2D TOF sequence can be useful in combination with the 3D TONE sequence.

Spiral-CT in diagnosis of vascular involvement in pancreatic cancer

BACKGROUND/AIMS

The purpose of this prospective study was to evaluate the efficacy of spiral-CT for the identification of portal venous, superior mesenteric artery and celiac trunk infiltration in the staging of pancreatic (n = 29) and periampullary (n = 6) cancers.

MATERIALS AND METHODS

All patients were examined by contrast enhanced spiral-CT using a total volume of 240 ml contrast medium i.v. With a slice thickness of 5 mm and a table increment of 7 mm/sec a overlapping data set, representing a total volume of 21 cm, was covered. The images were reconstructed in 4 mm intervals. In 28 patients the spiral CT results were correlated with surgical findings.

RESULTS

Regarding portal venous infiltration spiral-CT had a sensitivity of 91% (10/11), a specificity of 9.4% (16/17), a positive predictive value of 91% (10/11), a negative predictive value of 94% (16/17) and, an overall accuracy of 92.8% (26/28). Spiral CT correctly identified arterial involvement in 5 patients, and no false negative result compared to surgical findings was observed.

CONCLUSIONS

These results indicate that spiral-CT reliably verifies occlusion, stenosis and encasement of the major peripancreactic vessels caused by pancreatic cancer.

Noninvasive assessment of renal artery stenosis. A comparison of MR angiography, color Doppler sonography, and intraarterial angiography

The purpose of this study was to evaluate MR angiography (MRA) and color Doppler sonography as noninvasive screening methods in suspected renovascular hypertension. Fifty-five consecutive patients with arterial hypertension were examined prospectively using high resolution 3-D TOF MRA and color Doppler sonography. Intraarterial angiography was the standard of reference. Stenoses of 60% or more were regarded as significant. MR angiograms were evaluated by 3 independent observers who studied 110 main renal arteries. All 8 significant stenoses and 2 occlusions were correctly classified with MRA while one 60% stenosis was underestimated by color Doppler sonography. Mild stenoses were overestimated by MRA in 4 and by color Doppler sonography in 6 cases. A drawback of both methods was the large number of not evaluable arteries (6 in MRA, 11 in color Doppler sonography). These arteries were regarded as pathologic because stenosis could not be excluded. Due to this fact specificities of MRA and color Doppler sonography were 90% and 85% respectively. Accessory vessels were detected in 47% (8/17) by MRA and in 0% (0/17) by color Doppler sonography.

Delayed spontaneous opening of a self-expanding metal stent bridging a malignant esophageal stenosis

We report on a case of an 85-year-old man with dysphagia who suffered from a stenosing esophageal adenocarcinoma that could not be treated by surgery. The tumor demonstrated circumferential growth and extended from 14 to 22 cm from the incisors. There were no esophago-tracheal fistulas. The stenosis could be negotiated with the endoscope. Under fluoroscopic guidance, a self-expanding Strecker stent was placed in the stenosed area with no prior dilatation. After releasing the stent an x-ray revealed a twisted and wrinkled stent which had expanded to only half of its maximum diameter. The patient's symptoms had not improved. Four days later dysphagia resolved when the stent spontaneously corrected its position and was found to be maximally expanded. On the basis of this observation it may be concluded that, at least in some cases, self-correction of an initially unsatisfactory positioning of a Strecker stent may be expected, even after four days.

[Diagnostic imaging in acute pancreatitis]

With a sensitivity of 90% in the diagnosis of necrotic pancreatic tissue contrast-enhanced computed tomography is the most reliable imaging tool for classifying acute pancreatitis. ERCP is essential for the diagnosis of stones in the common bile duct and in the pancreatic ducts and of tumors of the duodenal papilla and the pancreatic head and thus for clarifying the etiology of acute pancreatitis. Sonography as the only imaging tool would not be sufficient, because its sensitivity for necrotizing pancreatitis is only 33% and stones in the common bile duct are often missed.

[The marking of the gastrointestinal tract in computed tomography: experiences with a barium sulfate contrast medium (Micropaque CT)]

Micropaque CT, a new suspension of barium sulphate, has recently become available for clinical use in abdominal CT. The attenuation of the 1.5 per cent solution, measured in vitro, was 222 HU (without artifacts). In about 45 per cent of the clinical examinations artifacts occurred which, however, were not disturbing. Sufficient opacification of stomach and bowel was achieved in 65 per cent. 55 per cent of patients found the suspension pleasant to take, ten per cent complained of mild diarrhoea. Micropaque CT is particularly suitable for upper abdominal CT in outpatients.

[CT-guided biopsy: methods, results and complications]

Percutaneous CT-guided biopsies were carried out in 350 patients; on 291 occasions, 14- or 18-gauge and, on 59 occasions, an 0.95 mm cutting biopsy cannula was employed. Using the 14- and 18-gauge needles, a histological diagnosis was possible in 191 cases, a sensitivity of 82.7%. The 0.95 mm cannulas proved successful in 39 of the 59 punctures, producing a markedly lower sensitivity of 66.2%. The most common cause of an incorrect biopsy with large needles was bad position of the needle, whereas the small needles provided inadequate material. Complications which, however, did not require treatment, occurred in 5 patients (1.4%).