Biomedical subjects

N Holzknecht

Publications and source records attributed to N Holzknecht.

At least 37 records · Page 2Linked to original sources

PubMed2000

Hepatic lesion detection and characterization: value of nonenhanced MR imaging, superparamagnetic iron oxide-enhanced MR imaging, and spiral CT-ROC analysis.

PURPOSE: To determine the accuracy for detection and characterization of focal hepatic lesions of nonenhanced, superparamagnetic iron oxide (SPIO)-enhanced, or a combination of nonenhanced and SPIO-enhanced MR imaging and contrast-enhanced spiral computed tomography (CT). MATERIALS AND METHODS: Spiral CT and T2-weighted SPIO-enhanced (ferucarbotran-enhanced) MR imaging were performed in 35 patients within 2 weeks before surgery for malignant hepatic lesions. Only malignant lesions with histopathologic proof were considered. A total of 875 images with and 800 images without focal lesions were presented to five readers, who were asked to assess the presence and characterization of lesions by using a five-point confidence scale. Receiver operating characteristic analysis was performed. RESULTS: Nonenhanced and SPIO-enhanced images together and SPIO-enhanced images alone yielded the best performance for lesion detection. No differences were found among all imaging techniques with regard to lesion characterization (benign vs malignant). The combined approach resulted in larger area under the ROC curve (A(z) = 0.9062) and accuracy (85.3%) (P < 0.02), as compared with SPIO-enhanced MR imaging (A(z) = 0.8667; accuracy, 73.1%). CONCLUSION: SPIO-enhanced T2-weighted MR imaging was more accurate than nonenhanced T1-weighted and T2-weighted MR imaging and contrast-enhanced spiral CT for the detection of focal hepatic lesions. The combined analysis of nonenhanced and SPIO-enhanced images was more accurate in the characterization of focal hepatic lesions than was review of SPIO-enhanced images alone.

Contrast Media↗

PubMed2000

Evaluation of the accuracy of gadobenate dimeglumine-enhanced MR imaging in the detection and characterization of focal liver lesions.

OBJECTIVE: We evaluated the extent to which hepatic lesion characterization and detection is improved by using gadobenate dimeglumine for enhancement of MR images. MATERIALS AND METHODS: Eighty-six patients were imaged before gadobenate dimeglumine administration, immediately after the 2 mL/sec bolus administration of a 0.05 mmol/kg dose (dynamic imaging), and at 60-120 min after the IV infusion at 10 mL/min of a further 0.05 nmol/kg dose (delayed imaging). The accuracy for lesion characterization was assessed for a total of 107 lesions. Sensitivity for lesion detection was assessed for a total of 149 lesions detected on either intra-operative sonography, iodized oil CT, CT during arterial portography, or follow-up contrast-enhanced CT as the gold standard. RESULTS: The accuracy in differentiating benign from malignant liver lesions increased from 75% and 82% (the findings of two observers) on unenhanced images alone, to 89% and 80% on dynamic images alone (p<0.001, p = 0.8), and to 90.7% when combining the unenhanced and dynamic image sets (p<0.001, p = 0.023). Delayed images did not further improve accuracy (90% and 91%; p = 0.002, p< 0.05). A similar trend was apparent in terms of accuracy for specific diagnosis: values ranged from 49% and 62% on unenhanced images alone, to 76% and 70% on combined unenhanced and dynamic images (p<0.001, p = 0.06), and to 75% and 70% on inclusion of delayed images (p<0.001, p = 0.12). The sensitivity for lesion detection increased from 77% and 81% on unenhanced images alone, to 87% and 85% on combined unenhanced and dynamic images (p = 0.001, p = 0.267), and to 92% and 89% when all images were considered (p<0.001, p = 0.01). CONCLUSION: Contrast-enhanced dynamic MR imaging with gadobenate dimeglumine significantly increases sensitivity and accuracy over unenhanced imaging for the characterization of focal hepatic lesions, and delayed MR imaging contributes to the improved detection of lesions.

Adult↗

PubMed2000

Effects of three different doses of a bolus injection of gadodiamide: assessment of regional cerebral blood volume maps in a blinded reader study.

BACKGROUND AND PURPOSE: Reconstruction of first-pass bolus information to derive regional cerebral blood volume (rCBV) maps is commonly performed in many centers; however, various protocols with different doses of paramagnetic contrast injections have been reported. We evaluated the dose dependency of rCBV maps in a brain tumor population by using three different doses of gadodiamide injection to evaluate their diagnostic accuracy in blinded reader sessions. METHODS: Eighty-three patients with intraaxial brain tumors (72 gliomas) were studied at three centers and randomized to receive a bolus injection of 0.1, 0.2, or 0.3 mmol/kg per body weight of gadodiamide. rCBV maps were generated from T2*-weighted gradient-echo echoplanar sequences at 1.5 T. Data processing was performed according to the indicator dilution theory. RESULTS: The mean contrast-to-noise ratio (CNR) was significantly different between gadodiamide doses of 0.1 and 0.2 mmol/kg (CNR = 8.7 and 15.7) and between 0.1 and 0.3 mmol/kg (CNR = 17.7). No significant difference was found between doses of 0.2 and 0.3 mmol/kg. Sensitivity for the differentiation of benign and malignant brain tumors was 80%, 95%, and 91%, and specificity was 45%, 54%, and 43% by blinded readings at 0.1, 0.2, and 0.3 mmol/ kg, respectively, as compared with histologic findings. Nonblinded readings had a sensitivity of 83%, 100%, and 90% and a specificity of 82%, 100%, and 73% at 0.1, 0.2, and 0.3 mmol/kg, respectively. CONCLUSION: A dose of 0.2 mmol/kg of gadodiamide is recommended for reconstruction of rCBV maps if data are acquired with the T2*-weighted protocol described.

Blood Volume↗

PubMed1999

T2-weighted breathold imaging of the liver: a quantitative and qualitative comparison of fast spin echo and half Fourier single shot fast spin echo imaging.

The imaging characteristics of two EPI-hybrid breath-hold sequences, T2-weighted fast spin-echo [FSE, effective echo time (TEeff) 138 ms] and half Fourier single shot turbo spin-echo (HASTE, TEeff 60 ms), were compared in hepatic imaging. A total of 111 patients with suspected hepatic disease were studied at 1.5 Tesla using a body phase-array coil. The signal-to-noise (S/N) and contrast-to-noise (C/N) ratios for organs and lesions were calculated and quantitatively compared. Organ delineation, visualization of anatomical structures and pathological lesions, artifacts, and total image quality were qualitatively assessed and statistically compared. The final diagnoses were metastases from colorectal, breast, and pancreatic cancer in 23/111, hepatocellular carcinoma in 15/111, cysts in 19/111, hemangiomas in 9/111, several other lesions in 7/111, and no lesions in 38/111 of the cases. A total of 139 lesion in 73% of the patients were seen while 85% of the lesions were at least 1.5 cm in size. Regarding S/Ns HASTE was significantly (P < 0.03) superior to FSE with only minor (P > 0.05) differences in C/Ns between the two sequences for anatomical and pathological structures. HASTE demonstrated in almost all (97.3%) of the cases no artifacts, while on fast SE imaging moderate to minor artifacts were present in 23.5-51.7% of the cases. The overall image quality and diagnostic confidence was rated significantly higher (good 43.2%, excellent 53.2%) for HASTE than for fast SE imaging (good 44.8%, excellent 17.6%). Providing comparable C/Ns for anatomical and pathological structures, breatheld HASTE imaging proved to be superior to fast SE in T2-weighted imaging of the upper abdomen regarding general image quality, and, with adequate technical prerequisites, may be a suitable substitute of fast T2-imaging techniques.

Evaluation Studies as Topic↗

PubMed1999

[Comparison of dual-phase helical CT with native and ferum oxide-enhanced magnetic resonance imaging in detection and characterization of focal liver lesions].

PURPOSE: Evaluation of the diagnostic efficacy of contrast-enhanced, dual-phase spiral CT and MRI before and after administration of SPIO particles in focal hepatic disease with previously uncertain diagnosis. MATERIAL AND METHODS: In 46 patients in whom primary or secondary hepatic malignancy was suspected, dual-phase spiral CECT and breath-held T1-weighted gradient-echo and T2-weighted fast spin-echo MRI (1.5 T, body-phased-array coil) before and after SPIO administration were compared. The indications for the subsequent MRI studies were based on ambiguous findings on CECT. The number of hepatic lesions, the overall lesion detection and characterization was evaluated by consensus and compared to the gold standard (histological proof in 30/46 of the cases, long-term follow-up in 16/46 of the cases). RESULTS: In 34 of 46 cases the correct diagnoses were established by CECT (sensitivity 96%, specificity 48%) revealing significantly less lesions than MRI. Unenhanced MRI had sensitivity of 93% and specificity of 71%, whereas SPIO-enhanced MRI had sensitivity of 97% and specificity of 88%. The differences between the modalities were even more pronounced in the detection of lesions smaller than 10 mm with SPIO-MRI as the most sensitive method. CONCLUSIONS: In this problem-oriented scenario, SPIO-enhanced MRI was superior to spiral CT and unenhanced MRI regarding the diagnostic efficacy in the pre-operative work-up of focal liver lesions. SPIO-enhanced MRI can be recommended as a problem-solving tool for the clinical routine.

Adult↗

PubMed1999

[Multislice computed tomography of the small intestine. Preliminary results].

SUBJECT: Spiral computer tomography (SCT) became an important supplement to the Sellink examination. Multi slice computer tomography (MSCT) achieves a z-axis resolution of 1-2 mm without considerable increase in the acquisition time. In this paper, examination technique in first clinical results of CT-Sellink examination with MSCT, including the 3D-reconstruction are presented. MATERIALS AND METHODS: The investigations were carried out with the Somatom Plus 4 Volume Zoom (Siemens, Forchheim) scanner. The following parameters were employed: 4 parallel detector ledges, collimation 4 x 1 mm, tube power 140 mA, tube voltage 120 kV, pitch 5 up to 6 mm, slice thickness 1 mm and 2 mm, reconstruction with 50% overlap. Via a duodenal tube, the small intestine was distended by means of 1.5 up to 2.5 l methyl-cellulose suspension. The data were acquired 35 s after injection of 120 ml contrast media (Ultravist). Various methods of postprocessing were applied on a workstation. RESULTS: As of yet, 16 patients were examined with MSCT-Sellink. In 4 cases pathological findings were detected with MSCT-Sellink, which were not recognized with X-ray Sellink. CONCLUSION: Due to high z-axis resolution and short acquisition time, the morphological details of the small intestine can be visualized utilizing MSCT-Sellink. The data set is well suited for 3D postprocessing. Improvement of diagnostic accuracy can be anticipated.

Adult↗

PubMed1999

[Evaluation of right heart load with spiral CT in patients with acute lung embolism].

PURPOSE: Purpose of this study was to evaluate whether spiral-CT allows judgment of right ventricular failure in patients with acute pulmonary embolism. MATERIALS AND METHODS: 61 patients underwent spiral-CT due to suspicion of acute pulmonary embolism. Patients with pulmonary embolism were divided into subpopulations according to the severity of pulmonary embolism in the CT scan. Cardiac measurements were performed on axial spiral-CT images and compared to those of patients without suspicion of pulmonary embolism or cardiac diseases. RESULTS: In 30 patients spiral-CT revealed acute pulmonary embolism. Significant differences in cardiac measurements in patients with severe and less severe pulmonary embolism were found on comparing the following dimensions: left ventricular width (p = 0.0003), left (p = 0.008) and right (p = 0.009) ventricular cross-sectional area, proportion of right to left ventricular width (p = 0.0003) and proportion of right to left ventricular cross-sectional area (p = 0.0001). The proportion of the cross-sectional areas (r = 0.65) and the proportion of the width (r = 0.60) of both ventricles correlated well with the severity of central pulmonary embolism. CONCLUSION: Besides reliable assessment of pulmonary embolism spiral-CT allows the evaluation of cardiac dimensions for judgment of right ventricular failure.

Adult↗

PubMed1998

[MRI of the small intestine with rapid MRI sequences in Crohn disease after enteroclysis with oral iron particles].

PURPOSE: To evaluate the efficacy of breathhold MRI following enteroclysis with addition of oral magnetic particles to study the extension, detection of stenoses and extraluminal manifestations in Crohn's disease. MATERIAL AND METHODS: 18 patients with Crohn's disease and potential of surgical intervention were studied with enteroclysis with addition of oral magnetic particles. T1-/T2-weighted breathhold MRI w/o spectral fat suppression w/o i.v. Gd-DTPA was applied. RESULTS: Typical findings were marked bowel wall thickening with strong contrast enhancement. 95.8% of affected small bowel segments and 94.7% of stenoses were correctly detected by MRI. All four fistulas were detected and important extraluminal findings were seen in 6/18 patients. Additionally, one ileoileal and two ileosigmoidal adhesions, two extraluminal abscesses and affection of the right ureter were delineated. CONCLUSION: MRI in Crohn's disease offers the potential to avoid radiation exposure in this relatively young patient group. Important additional findings relevant to indication of surgery are seen in approximately one third of cases. The replacement of transduodenal intubation by oral contrast application remains to be further studied.

Administration, Oral↗

PubMed1998

[Focal liver diseases].

INTRODUCTION: Advanced therapies are improving significantly the survival of patients with malignant focal liver disease. For efficient implementation of these surgical and interventional techniques a clear concept of the diagnostic procedure is mandatory. METHODS: Based on a review of the current literature, the different imaging modalities, including ultrasound, computed tomography, magnetic resonance tomography, nuclear medicine and angiography, are discussed and evaluated for their diagnostic efficacy in focal hepatic disease. RESULTS: Considering clinical, diagnostic, and economical appropriateness, recommendations for diagnostic strategies in different clinical scenarios regarding focal heptic disease are presented. CONCLUSION: If the power of specific imaging methods are relevant clinical information is known, problem-based diagnostic strategies help to avoid unnecessary, expensive and time-consuming studies in the work-up of focal liver lesions.

Carcinoma, Hepatocellular↗

PubMed1998

[Ultrasonography of veins].

PURPOSE: The high incidence of acute and chronic diseases of the venous system requires the application of reliable, non-invasive, low-cost methods in diagnosis and follow-up after therapy. MATERIAL AND METHODS: Current technology, principles of examination, and results of ultrasonography of the peripheral venous systems are reviewed. RESULTS: Since the mid 1980s, compression ultrasonography (US) has been introduced in the diagnosis of deep venous thrombosis. Doppler-US methods reach the hallmarks of venous imaging, particularly since the advent of color duplex US. In thrombosis, postthrombotic syndrome, and primary varicosis, color duplex US increasingly replaces the "gold standard" of phlebography as the imaging method of choice. Venous diseases of the neck, and of the upper and lower extremities are reliably recognized by color duplex US. New areas of application of Doppler and duplex-US include examinations of the venous system in patients in intensive care units, evaluation of transplanted organs, and the demonstration of blood flow in hemodialysis shunts. CONCLUSIONS: Color duplex US is useful in most imaging investigations of the peripheral veins. In view of cost development in the medical imaging sector, however, in which ultrasonography takes a major part, critical indication for the application of Doppler- and duplex-US in the diagnosis and follow-up of venous disease is out most importance.

Humans↗

PubMed1998

[Vena cava filter. Indications, complications, clinical evaluation].

INTRODUCTION: Pulmonary embolism is the third leading cause of death in the western countries. If anticoagulation fails or is contra-indicated, or if the risk for pulmonary embolism is increased for other reasons, the percutaneous implantation of a vena cava filter should be considered. METHODS: The available filters can be differentiated by the design (cone, basket, net-types), by the material, and by their removability. The rate of complications (caval thrombosis, fracture of filter) and the in vitro efficacy in trapping thrombotic clots is dependent on the specific filter type. RESULTS: In clinical practice there is no evidence for significant differences in trapping efficacy among the different filters. About 4% of all patients treated by caval filters still can have pulmonary embolism, and 1% will have a fatal outcome. Dependent on the filter type, the most common complication is caval thrombosis, in up to 25% of cases. CONCLUSION: The percutaneous implantation of caval filters can readily be performed by interventional radiologists. However, randomized clinical studies failed to clearly document efficacy of caval filters. Therefore, indication has to be considered carefully.

Humans↗

PubMed1998

[Diagnosis of pulmonary embolism with spiral and electron-beam CT].

PURPOSE: To compare spiral (SCT) and electron-beam CT (EBT) for the diagnosis of pulmonary embolism (PE). MATERIALS AND METHODS: From June 1997 to June 1998 188 patients with suspected acute or chronic thromboembolism of the pulmonary arteries were examined. A total of 108 patients were scanned using SCT and 80 patients using EBT. On each scanner two different scan protocols were evaluated. RESULTS: PE was diagnosed in 38 patients using EBT and in 49 patients using SCT. Especially with EBT, isolated peripheral emboli could be confidently diagnosed. When EBT and SCT were compared for the analysis of peripheral pulmonary arteries, some paracardiac segmental and subsegmental vessels were significantly better analyzable with EB. Additional or diseases other than PE were diagnosed in 112 patients. Other diagnoses included bronchial carcinoma and aortic dissection. CONCLUSIONS: Advanced CT scanning techniques allow the highly accurate diagnosis of central and peripheral PE. Other potentially life-threatening underlying diseases are also readily recognized.

Aortic Dissection↗

PubMed1998

Breathhold MR urography: comparison between HASTE and RARE in healthy volunteers.

The purpose of our study was to determine relative values of rapid acquisition relaxation enhancement (RARE) and half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences in breathhold magnetic resonance (MR) urography in healthy volunteers under nonobstructive conditions of the urinary tract. A total of 20 healthy volunteers underwent MR urography with breathhold RARE and HASTE sequences at 1.5 T. For evaluation, the urinary tract was divided into nine segments on each side. Visualization of segments and artifacts was scored and the intensity ratios (InR) were determined. The upper five urinary segments were sufficiently visualized with RARE and significantly better with HASTE (renal calices, p = 0.002-0.037). The middle and lower ureter was sufficiently delineated both with RARE and HASTE, but HASTE images were statistically superior (p = 0.009-0.041). Both in RARE and HASTE images, the lower ureter was frequently superimposed by bowel contents and bowel motion. Superimposition of genital organs degraded image quality in eight of ten female volunteers. InRs were superior with HASTE in the kidney and ureter (p = 0.0003-0.0125). RARE InRs were higher in the bladder (p = 0.0008-0.014). We concluded that neither the RARE nor the HASTE sequences allowed the evaluation of the entire urinary tract under nonobstructive conditions. Although it cannot entirely replace intravenous urography, MR urography seems to lend itself to combination with other MR techniques, particularly in the investigation of pelvic or retroperitoneal disease.

Adult↗

PubMed1998

Breath-hold MR cholangiography with snapshot techniques: prospective comparison with endoscopic retrograde cholangiography.

PURPOSE: To compare findings with magnetic resonance (MR) cholangiography with rapid acquisition with relaxation enhancement (RARE) and half-Fourier acquisition with single-shot turbo spin-echo (hereafter, half Fourier RARE) snapshot imaging techniques to those with endoscopic retrograde cholangiography (ERC). MATERIALS AND METHODS: Heavily T2-weighted thick-section (RARE) and thin-section (half-Fourier RARE) MR cholangiography were performed prospectively, on a 1.5-T imager, in the biliary tree of 61 consecutive patients before ERC. Findings at ERC were considered the standard of reference. The radiologist and endoscopist were blinded to each other's report. On- and off-site MR cholangiographic readings were performed to detect stones (n = 24), biliary dilatation (n = 34), or stenosis (n = 36). RESULTS: The sensitivity and specificity of MR cholangiography, respectively, calculated on a lesion-by-lesion basis, were 92.3% and 95.8% for cholangiolithiasis, 94.1% and 92.6% for duct dilatation, and 88.8% and 84.0% for stenosis. With snapshot MR cholangiography, on a patient-by-patient basis, differentiation between normal (n = 15) and abnormal (n = 46) results yielded a sensitivity of 92.4%, a specificity of 83.4%, and a positive predictive value of 95.6%. Pitfalls were caused by flow artifacts, compression by vessels, and low contrast between calculi and surrounding parenchyma. CONCLUSION: Snapshot MR cholangiography allowed noninvasive, accurate detection of biliary stones, strictures, and dilatation similar to that with ERC. Discrepancies regarding low-grade dilatation and strictures had no clinical relevance at retrospective review.

Bile Duct Diseases↗

PubMed1997

[Initial experiences with contrast enhanced MR angiography after kidney and pancreas transplantation].

PURPOSE: The assessment of vascular complications by DSA in patients who have undergone kidney and pancreas transplantation is an invasive investigation and has the risk of nephrotoxicity caused by the iodinated contrast agent. The aim of this study was to compare the diagnostic value of noninvasive gadolinium--enhanced MRA with intraoperative and DSA results. PATIENTS AND METHODS: Eleven MRA investigations were performed in eight patients after kidney and pancreas transplantation. A fast T1-weighted 3D-gradient-echo sequence with short TR and TE was used in a dynamic technique including the three consecutive data acquisitions after a Gd-DTPA (Magnevist) injection. MRA was compared with intraoperative findings in all patients and with DSA in three patients. RESULTS: In the distal abdominal aorta, the internal and external iliac arteries, the main transplanted arterial vessels, and the arteries after first branching, high signal intensity was found. Assessment of renal and pancreatic parenchyma perfusion was possible in all patients. Venous transplant vessels could be depicted in four patients. CONCLUSION: Our initial experience with the MRA sequence used shows that this technique may be promising in the assessment of larger arterial transplanted vessels and kidney/pancreas parenchyma perfusion. Improvement of the MRA technique is necessary for transplanted venous vessels.

Angiography, Digital Subtraction↗

PubMed1997

[Gadolinium-enhanced magnetic resonance angiography of abdominal blood vessels].

Contrast enhanced (CE) magnetic resonance angiography (MRA) provides high resolution angiograms within 20-40 sec. The technique is based on the acquisition of heavily T1-weighted three-dimensional (3D) gradient-echo data sets (FISP) with ultrashort echo-(< 2ms) and repetition times (< 5 ms) during arterial phase of an intravenously injected bolus of a T1-shortening agent such as Gd-DTPA. For MR-angiography of abdominal vessels CE-MRA is better suited than "time-of flight" (TOF) and phase-contrast (PC) MRA because motional artifacts can be obviated with breath-held acquisitions. We have optimised the technique and evaluated its potential for angiography of the abdominal aorta and its branches as well as the portal vein and its tributaries. Whilst CE-MRA provides reliable diagnostic accuracy in the aorta and the proximal sections of its branches, small peripheral arteries cannot be assessed accurately. The portal vein and its tributaries can often be depicted better with CE-MRA than with conventional angiography but, like conventional angiography, CE-MRA is hampered by slow and reversed flow, conditions under which TOF or "true FISP" MRA may perform bst. We have also investigated FLASH-echo-planar imaging (EPI) hybrid techniques, a further technical development which due to shorter acquisition times of 12-15 sec. allows semi-dynamic imaging of the arterial and venous phase and provide better vessel contrast due to the use of fat-suppression.

Abdomen↗

PubMed1997

Choledocholithiasis after Billroth II surgery: MR cholangiographic diagnosis.

In this case of choledocholithiasis in a patient with previous Billroth-II surgery and cholecystectomy we demonstrate the advantages of a heavily T2-weighted half-Fourier turbo-spin-echo (HASTE) sequence. This technique allows thin-slice snapshot imaging with 1.4 s per slice eliminating motion artifacts and still has the necessary heavy T2-weighting to depict biliary fluid with high contrast. In the presented case endoscopic retrograde cholangiography (ERCP) could not be performed prior to MRI due to technical problems. In a second attempt, ERCP was successful and a common bile duct stone as diagnosed by MRI before could be removed. We conclude that HASTE snapshot MR cholangiography can be used as a clinically valuable tool when other noninvasive methods are not diagnostic.

Aged↗

PubMed1997

[A report on experience with a second-generation PACS installation in routine computed tomographic operations].

PURPOSE: Our institute has been using a pilot SIENET-PACS system for the last five years; its advantages and disadvantages in daily use are described. MATERIAL AND METHODS: The SIENET system connects 2 CT, 3 MRT and 2 angiographic installations with 7 viewing consoles and with an optical archive. From January 1994 to 1997 approximately 19,000 patients were examined by CT and the results stored digitally in the PACS system. RESULTS: A representative analysis of selected patient data revealed problems in 12.8% of patients with regard to the radiological information system and also the hospital information system. While the digital data proved satisfactory, the production of digital images was excellent but time-consuming. The image archive was reliable but required greater capacity for our purposes. CONCLUSIONS: Manual retrieval of patient data presented problems and integration of the radiology information system and PADS is essential. Digital data gathering is an advantage. Digital imaging is too slow and should be improved by more suitable software. Integration of new archival storage methods and compatibility with the DICOM standard is, judging form our experience, essential.

Angiography, Digital Subtraction↗