Local topological analysis of densitometer-generated scan images of the proximal femur for differentiation between patients with hip fracture and age-matched controls.

SUMMARY: We evaluate densitometer-generated scan images of the proximal femur with respect to topological properties of bone mineral distribution patterns in selected regions of interest. In a population of 100 post-menopausal women, the method has a highly discriminative potential with a performance superior to standard densitometry. Results vary with anatomical location within the proximal femur. INTRODUCTION: The objectives of the study were to evaluate densitometer-generated scan images of the proximal femur with respect to topological properties of bone mineral distribution patterns in selected regions of interest, to test the ability for differentiation between post-menopausal women hip fracture and controls, and to compare results with standard bone densitometry. MATERIALS AND METHODS: We used dual-energy X-ray absorptiometry (DXA) to measure the femoral bone mineral density (BMD) of 100 post-menopausal women (73.4 +/- 12.2), 50 of whom had a recent hip fracture. Local bone mineral distribution in the scanner-generated images was analyzed in the standard DXA-regions of interest (ROIs; femoral neck, the shaft, the trochanteric area; and the total hip) using an optimized, local topological parameter MF2D. Performance of topological analysis and BMD was tested by receiver-operator characteristic and discriminant analysis. RESULTS: Area under the curve (AUC) for correct differentiation between patients with and without fractures by BMD in the different ROIs ranged from 0.64 to 0.71; AUC of regional density-pattern analysis varied between 0.79 and 0.84. Using multivariate statistical models, between 71% and 84% of patients were correctly identified as fracture/non-fracture cases by regional topological analysis, whereas BMD reached levels from 58% to 68%. CONCLUSION: Our analysis indicates that identification of patients with hip fracture by regional evaluation of density patterns varies with anatomical location within the proximal femur. In our study population, performance of the novel parameter was superior to densitometry.

Using Radon transform of standard radiographs of the hip to differentiate between post-menopausal women with and without fracture of the proximal femur.

UNLABELLED: Texture features based on the Radon transform were extracted from clinical radiographs of the hip in post-menopausal women. The novel algorithm allowed us to identify patients with fracture of the proximal femur and may provide an alternative to measuring bone mineral density in predicting the fracture-risk in osteoporosis, especially where densitometry is regionally unavailable. INTRODUCTION: The aim of this study is to introduce an algorithm for differentiation between patients with and without fracture of the hip using parameters based on the Radon transform (RT) and applied to standard radiographs of the proximal femur and to compare the results with bone mineral density (BMD). METHODS: The study comprised 50 post-menopausal women (78.6 +/- 11.5 years of age), including 25 patients with hip fracture and 25 age-matched controls. We obtained lumbar and femoral BMD and standard femoral radiographs. In the radiographs we analysed trabecular patterns of the hip in a region-of-interest of 57 x 29 mm using the RT. From the histogram-representation of the RT, we extracted several characteristic parameters. By ROC and discriminant-analysis, we assessed the statistical power of both methods. RESULTS: For correct differentiation between fracture and non-fracture cases by femoral BMD, area-under-the-curve (AUC) was 0.78; AUC for the RT-based parameters ranged from 0.73 to 0.8. By combination of densitometric and textural information in a multivariate model the fracture status of 84% of subjects was predicted correctly, identification of fracture cases rose to 88%. CONCLUSION: Identification of fracture patients by RT applied to femoral radiographs was feasible and seemed to have a discriminative potential comparable to that of standard densitometry. In the future, the new method may provide an alternative to DXA or in conjunction with conventional densitometry may enhance the detection of patients with elevated risk of hip fracture.

Magnetic resonance imaging in early stage charcot arthropathy: correlation of imaging findings and clinical symptoms.

OBJECTIVE: To report on qualitative and quantitative MRI findings in early stage of diabetic osteoarthropathy (CA) and correlation with clinical symptoms. MATERIALS AND METHODS: Clinical data of 13 patients (mean age = 61.2 years) with Charcot arthropathy (CA, Eichenholtz 0) were compared with findings in native and contrast-enhanced MRI. 12 patients had diabetes mellitus (7 type 2, 5 type 1), one had idiopathic polyneuropathy. Evaluation was performed at acute stage of CA and at a 4 months follow-up. After baseline assessment, patients were treated with pressure-relieving means. Mean values of signal-intensity in short T1 inversion recovery (STIR) images of bones of the foot and ankle and corresponding contrast-enhancement were evaluated. Additional MRI-findings (soft tissue edema, varicosis, tenovaginitis, joint effusion) were analyzed. A correlation with symptoms (reddening, swelling, hyperthermia, pain) was performed. RESULTS: Bone marrow edema in affected bones significantly decreased (p<0.001). Soft tissue edema and pain showed a significant correlation with intensity of bone marrow edema (p<0.05). The presence of bone marrow edema in the STIR sequence was strongly associated with a corresponding contrast enhancement (p<0.0001, kappa-coefficients 0.976 at baseline and 0.953 at follow-up). CONCLUSION: MRI in early stage of CA provides valuable diagnostic information on the activity of the disease. A significant correlation of intensity of bone marrow edema in MRI and some clinical parameters (soft tissue edema and pain) was found. Paramagnetic contrast-agent did not provide additional information. This is the first report on quantitative assessment of signal alterations in stage 0 CA before and after treatment.

[Reality of treatment of osteoporotic fractures in German trauma departments. A contribution for outcome research]. / Versorgungswirklichkeit bei osteoporosebedingten Frakturen in der deutschen Unfallchirurgie. Ein Beitrag zur Versorgungsforschung.

The implementation of clinical pathways has a proven positive effect on the diagnostic workup and initiation of therapy in osteoporotic fracture patients. Unlike in most countries, fracture care in Germany is provided by so-called trauma surgeons. Therefore, it is essential to focus on the trauma surgeon for correct diagnostic workup and therapy initiation after a fragility fracture. A questionnaire was mailed to 409 departments of traumatology inquiring about the existence of a standardized clinical pathway for diagnosis and treatment of patients with fragility fractures. One of the central issues of the survey was whether those pathways comply with national guidelines. Only institutions that stated that they followed a clinical pathway were analyzed. 80% of institutions took part in our survey, 35% of which reported following a defined clinical pathway. Diagnostic workup is in concordance with the national guidelines in 30%, and therapy is guideline-based in 51%, with 12% basing both diagnostic workup and therapy on the guidelines. Thus, the vast majority of German traumatology departments do not follow national guidelines regarding osteoporosis diagnostics and therapy in patients with fragility fractures, leading to a great opportunity to improve fragility fracture care by means of both education and interdisciplinary cooperation.

[Progredient intracranial bleeding after traumatic brain injury. When is a control CCT necessary?]. / Grössenprogrediente intrakranielle Blutungen nach Schädel-Hirn-Trauma. Wann ist eine Kontroll-CCT erforderlich?

BACKGROUND: The aim of the study was to quantify the occurrence of progressive intracranial bleeding (PIB) and to identify concomitant parameters in patients suffering from traumatic brain injury (TBI). METHODS: TBI patients were included if initial and serial cranial computed tomography (CCT) scans were conducted within 24 h after trauma. A progression of > or =25% was considered as PIB. Patients with progression were compared to those with constant bleeding regarding clinical parameters, time lapse and coagulation status. RESULTS: A total of 98 patients with TBI and intracranial hemorrhaging were analyzed. PIB was detected in 45 patients showing significantly more intracerebral bleeding as well as fractures to the skull (p<0.05), compared to patients with constant bleeding. No significant differences between the groups regarding demographic and clinical parameters, time interval between trauma and initial CCT, and coagulation status were found. CONCLUSIONS: Early progression of intracranial hemorrhaging occurs in nearly every second TBI patient and is recognized frequently in cerebral contusions and after fractures to the skull. Hence, early repeated CT scanning is indicated in all TBI patients suffering from intracranial bleeding.

[Analysis of failure modes in multislice computed tomography during primary trauma survey]. / Analyse von Verzögerungen der Schockraumdiagnostik bei Einsatz der Mehrschicht-Spiral-Computertomografie.

PURPOSE: In the case of major trauma, immediate recognition and treatment of life-threatening conditions are essential. An increasing number of European trauma centers use MSCT during the primary trauma survey due to its high diagnostic precision and speed. However, there is currently little empirical data about failures in this process to practice quality assurance. The aim of this study was to evaluate this process under operating resuscitation conditions and to identify failure modes that caused delays in completion. MATERIALS AND METHODS: An independent study monitor documented the course of trauma room treatment during a 10-month period. The inclusion criteria were patients who were admitted directly from the accident scene and the study monitor was present at the time of admission. RESULTS: According to our ATLS-based trauma algorithm whole-body CT (WBCT) consists of non-contrast head CT (CCT) and contrast-enhanced trunk CT (TCT). 57 trauma patients receiving 45 WBCT. 5 single CCT and 4 single TCT studies were evaluated. After initial resuscitation, CCT was obtained within 17 min of trauma room admission (IQR 13.0 - 20.0). In 20 % (95 %CI 9 - 31 %) of the cases, a CCT delay of median 5.0 min (IQR 3.8 - 8.0) was observed caused by e. g. earings, piercings and ECG cables in the scan field or intoxicated patients. Contrast-enhanced TCT was performed after 23.0 min (IQR 19.0 - 27.0). Due to preventable errors 12 of the 49 TCT studies were delayed (25 % 95 %CI 12 - 37 %) for 5 min (IQR 3.0 - 8.0). CONCLUSION: Under "front line" conditions every fifth CCT and every fourth TCT study was completed with a median delay of 5 min. An independent process analysis revealed that unpreventable delays were due to uncooperative patients or system failure. Preventable delays were due to errors such as short intravenous lines or deviation from trauma room algorithms. Preventable delays could be avoided by addressing human and technical aspects such as revising checklists and functional architecture of the trauma bay. The failure mode and effect analysis (FMEA) method would assure quality in this process.

[Comparison of C-arm CT and standard imaging in osteosyntheses of fractured distal radius specimens]. / Ein Vergleich von C-Bogen-CT und Standardbildgebung an Osteosynthesen frakturierter Präparate des distalen Radius.

BACKGROUND: The purpose of this study was to evaluate the value of C-arm CT imaging of the distal radius with standard patient positioning in intraoperative assessment of plate osteosynthesis. MATERIALS AND METHODS: Four complete distal radius specimens from human cadavers were fractured (type C), and internal fixation with palmar plates (stainless steel) was then carried out in each. On the basis of C-arm fluoroscopy, radiography and C-arm CT (Siremobil Iso-C3D, scans with forearm bones positioned parallel to the z-axis), 19 observers subsequently evaluated the positions of screws near the joint and any steps within the joint, after which the bones were surgically exposed and the imaging results checked against direct visual observations. RESULTS: No statistically significant differences were detected either between the modalities or between the evaluator groups. CONCLUSION: With standard patient positioning, the performance of C-arm CT was equivalent to and not better than that of current standard procedures, i.e. intraoperative fluoroscopy and postoperative radiography. Further studies should examine whether this holds true in clinical practice with representative patient collectives when titanium implants are used and/or optimized patient positioning is practised.

[Contemporary diagnostics and therapy of osteoporosis]. / Zeitgemässe Diagnostik und Therapie der Osteoporose.

Since the World Health Organisation's announcement of the "Bone and Joint Decade 2000-2010" diseases of the musculoskeletal system attract more and more attention throughout patients and professional health care providers. In an aging society especially osteoporosis represents a major public health concern. Fragility fractures are the most limiting condition in osteoporosis with the highest impact on both, life quality and health care systems worldwide. Orthopaedic surgeons play a key role in implementing primary diagnostics and therapy in patients with fragility fractures. Objective of this effort is the reduction of the common subsequent fractures in patients with osteoporosis. According to national and international guidelines implementation of contemporary clinical pathways to diagnose and treat patients with fractures due to diminished bone mineral density is fast, simple and proven to be effective.

[Comparison of different review displays with respect to the detection of low-contrast details in digital radiographs]. / Vergleich unterschiedlicher Bildwiedergabegeräte bei der Erkennung von Niedrigkontrastdetails in digitalen Radiographien.

PURPOSE: Assessment of low-contrast details in digital radiographs on different review displays (RD). MATERIALS AND METHODS: 20" flat screen panels (RD1: standard color LCD-TFT, RD2: monochrome LCD-TFT for radiological reading, RD1*: RD1 with optional image inversion; 205 cd/m (2) luminance, respectively) were evaluated. At 30 lx ambient lighting, 10 radiologists gradually increased the contrast (constant steps) for both a homogeneous picture and a cutout of a thorax radiography of n = 480 simulated nodules until they became recognizable. RESULTS: In the case of bright nodules on an anthropomorphic background, the use of image inversion produced significantly better results. No other significant differences were detected. CONCLUSION: Provided that the working environment is not bright, the results suggest that low-cost RD can be used for the recognition of low-contrast details in radiographies of the chest. Further studies including more display models are necessary. Among different ambient lighting and luminance settings, these studies should include a closer analysis of the special features of digital systems such as brightness/contrast adaptation, picture enlargement (zoom shot), and image inversion.

[CT-guided vertebroplasty and kyphoplasty: comparing technical success rate and complications in 101 cases]. / CT-gesteuerte Vertebro- und Kyphoplastie: Vergleichende Untersuchung zu technischem Erfolg und Komplikationen bei 101 Eingriffen.

PURPOSE: To compare the technical success and complication rates in CT-guided vertebroplasty and kyphoplasty. MATERIALS AND METHODS: From 2002 - 2005 69 patients (101 vertebrae) were treated with vertebroplasty (n = 82) or kyphoplasty (n = 19) using 4-slice MSCT with CT fluoroscopy as the sole guidance for the procedure. The underlying lesions were osteoporotic fractures in 78 vertebral bodies and 23 vertebral metastases. RESULTS: Technical success was achieved in all 101 procedures. Post-interventional CT demonstrated asymptomatic cement leakage in 51/101 vertebrae. Kyphoplasty resulted in leakage in 11/19 (57.9 %) and vertebroplasty in 40/82 (48.8 %) procedures. With p = 0.48 (Mann-Whitney Test) there was no significant difference between kyphoplasty and vertebroplasty with respect to the number of cement leakage occurrences. There was one minor complication of an L5 root irritation following radiofrequency ablation and vertebroplasty of a sarcoma metastasis which subsided without treatment after 8 weeks. There was one major complication of intraspinal cement leakage during tumor vertebroplasty causing T5 root compression and requiring laminectomy for cement removal. The overall rate of major complications requiring treatment was 0.99 %. CONCLUSION: Vertebroplasty and kyphoplasty can be safely performed using only MSCT fluoroscopy guidance. The rate of major complications is very low. There was a high rate of small asymptomatic cement leakages which may have remained undetected with conventional fluoroscopy (CF). There was no statistically significant advantage for kyphoplasty with respect to cement leakage and the technical success rate.

Development of an accelerated MSCT protocol (Triage MSCT) for mass casualty incidents: comparison to MSCT for single-trauma patients.

During multiple casualty incidents (MCI) emergency radiology departments have to deal with a large number of patients with suspected severe trauma within a short period of time. The aim of this study was to develop a suitable accelerated multislice computed tomography (MSCT) protocol to increase patient throughput for this kind of emergency situation. We presumed a scenario of 15 patients being admitted to the trauma service with suspicion of severe injuries after a MCI over a period of 2 h. An accelerated Triage MSCT protocol was developed and evaluated for MSCT scanner productivity (patients per hour) and time (minutes) needed for a total MSCT body workup using an anthropomorphic phantom. In addition, time (minutes) for transfer and preparation was measured. These timeframes were compared to a control group consisting of 144 single patients with multiple trauma undergoing standard MSCT according to our trauma room protocol. All MSCT studies were conducted using a 4-detector row scanner. (1) For the study group (Triage MSCT), average time for patient transfer and preparation was 2.9 min (2.5-4.3 min), mean CT examination time was 2.1 min (1.7-2.4 min); image reconstruction took 4.0 min (3.3-4.3 min). Total time in scanner room was 8.9 min (7.7-11.3 min), resulting in a maximal productivity of 6.7 patients per hour. Image transfer to the digital picture archive and communication system archive was completed after an average 9.5 min (8.9-10.8 min). (2) For the control group (single casualty MSCT), the mean time for patient transfer and preparation was 20.4 min (9.0-39.2 min), mean examination time was 6.0 min (3.1-11.3 min). Times for image reconstructions were not recorded in the patient series. Mean total time in scanner room was 25.3 min (11.0-72.4 min), resulting in a patient throughput of 2.4 patients per hour. MSCT has potential to serve as a powerful tool in triage of multiple casualty patients. The introduction of a Triage MSCT scanning protocol resulted in an increase of patient throughput per hour by a factor of almost 3.

[Role of osteoporosis in trauma diagnostics]. / Stellenwert der Osteoporose in der traumatologischen Diagnostik.

PURPOSE: To evaluate the current bone mineral density (BMD) distribution in elderly patients hospitalized due to traumatic hip fracture and to assess the necessity of concomitant pharmacotherapy of underlying osteoporosis. MATERIALS AND METHODS: 58 female patients > or = 50 years (mean 81 years) with proven hip fracture were included. The diagnosis of fracture was established either by conventional radiography (CR) or by computed tomography (CT). BMD was assessed prospectively by means of dual energy X-ray absorption (DXA) measurement of the lumbar spine and/or femoral neck. DXA data was routinely achieved by analysis of T- and Z-values of the BMD. Distribution of BMD was assessed. Results for both measurement sites were compared using T-test and Pearson correlation analysis. RESULTS: 56/58 patients with proven hip fracture received DXA of the lumbar spine, 51 DXA of the femoral neck. The mean BMD was 0.829 +/- 0.137 g/cm (2) (lumbar spine) and 0.451 +/- 0.126 g/cm (2) (femur). T-values were - 2.8 +/- 1.14 (lumbar spine) and - 3.53 +/- 0.97 (femur). Compared to the normal distribution (lumbar spine), 53 patients (94.6 %) had diminished BMD (T < or = - 1). Of these 15 (26.8 %) had osteopenia (T > - 2.5) and 38 (67.9 %) had osteoporosis (T < or = - 2.5) according to WHO definition. With respect to femoral bone measurement, all patients (100 %) had diminished BMD (T < or = - 1), 9 patients (17.6 %) had osteopenia (T > - 2.5) and 42 patients (82.4 %) had osteoporosis (T < or = - 2.5). Results for different measurement sites differed significantly and were weakly correlated. CONCLUSION: This data indicate that diminished BMD in terms of osteopenia or osteoporosis is a frequent finding in hip fractures of elderly females. A large majority of these elderly patients therefore should be treated according to recent guidelines for treatment of osteoporosis. Our data indicate that this entity is potentially underdiagnosed and should be considered by radiologists as well as traumatologists.

[Radiological intervention in multiply injured patients]. / Radiologische Interventionen bei polytraumatisierten Patienten.

The most frequent cause of mortality during the first 4 h following severe trauma is uncontrollable hemorrhage from large arteries and parenchymal organs, whereas traumatic injuries of the heart and aorta are responsible for sudden death occurring at the accident site. It is therefore mandatory to diagnose and treat these injuries rapidly. Multislice spiral computed tomography is a highly useful imaging modality for severely injured patients. In this group of patients, various interventional procedures such as embolisation, stenting and temporary balloon occlusion may contribute to saving lives. In ruptures of the aorta and major arteries, stenting and temporary balloon occlusion may prevent exsanguination. Transcatheter embolisation is useful in hemorrhage from visceral organs, arteriovenous fistulas and secondary onset hemorrhage.

Initial clinical results with a new needle screen storage phosphor system in chest radiograms.

PURPOSE: To evaluate image quality and anatomical detail depiction in dose-reduced digital plain chest radiograms using a new needle screen storage phosphor (NIP) in comparison to full dose conventional powder screen storage phosphor (PIP) images. MATERIALS AND METHODS: 24 supine chest radiograms were obtained with PIP at standard dose and compared to follow-up studies of the same patients obtained with NIP with dose reduced to 50 % of the PIP dose (all imaging systems: AGFA-Gevaert, Mortsel, Belgium). In both systems identical versions of post-processing software supplied by the manufacturer were used with matched parameters. Six independent readers blinded to both modality and dose evaluated the images for depiction and differentiation of defined anatomical regions (peripheral lung parenchyma, central lung parenchyma, hilum, heart, diaphragm, upper mediastinum, and bone). All NIP images were compared to the corresponding PIP images using a five-point scale (- 2, clearly inferior to + 2, clearly superior). Overall image quality was rated for each PIP and NIP image separately (1, not usable to 5, excellent). RESULTS: PIP and dose reduced NIP images were rated equivalent. Mean image noise impression was only slightly higher on NIP images. Mean image quality for NIP showed no significant differences (p > 0.05, Mann-Whitney U test). CONCLUSION: With the use of the new needle structured storage phosphors in chest radiography, dose reduction of up to 50 % is possible without detracting from image quality or detail depiction. Especially in patients with multiple follow-up studies the overall dose can be decreased significantly.

[Possibilities for workflow optimization in radiology departments beyond RIS and PACS]. / Möglichkeiten der Optimierung des Workflows in radiologischen Abteilungen jenseits von RIS und PACS.

Technological progress and the rising cost pressure on the healthcare system have led to a drastic change in the work environment of radiologists today. The pervasive demand for workflow optimization and increased efficiency of its activities raises the question of whether by employment of electronic systems, such as RIS and PACS, the potentials of digital technology are sufficiently used to fulfil this demand. This report describes the tasks and structures in radiology departments, which so far are only insufficiently supported by commercially available electronic systems but are nevertheless substantial. We developed and employed a web-based, integrated workplace system, which simplifies many daily tasks of departmental organization and administration apart from well-established tasks of documentation. Furthermore, we analyzed the effects exerted on departmental workflow by employment of this system for 3 years.

[PACS: storage and retrieval of digital radiological image data]. / PACS: Speicherung und Abruf digitaler radiologischer Bilddaten.

BACKGROUND: Efficient handling of both picture archiving and retrieval is a crucial factor when new PACS installations as well as technical upgrades are planned. MATERIALS AND METHODS: For a large PACS installation for 200 actual studies, the number, modality,and body region of available priors were evaluated. In addition, image access time of 100 CT studies from hard disk (RAID), magneto-optic disk (MOD), and tape archives (TAPE) were accessed. RESULTS: For current examinations priors existed in 61.1% with an averaged quantity of 7.7 studies. Thereof 56.3% were within 0-3 months, 84.9% within 12 months, 91.7% within 24 months, and 96.2% within 36 months. On average, access to images from the hard disk cache was more than 100 times faster then from MOD or TAPE. CONCLUSION: Since only PACS RAID provides online image access, at least current imaging of the past 12 months should be available from cache. An accurate prefetching mechanism facilitates effective use of the expensive online cache area. For that, however, close interaction of PACS, RIS, and KIS is an indispensable prerequisite.

[Osteoporosis in traumatology. Prevalence and management]. / Osteoporose in der Unfallchirurgie. Prävalenz und Management.

BACKGROUND: A fracture occurring in osteoporosis is a sentinel event but very rarely leads to bone mineral density (BMD) measurement or sufficient drug therapy. We designed an algorithm to evaluate BMD in older fracture patients and tested it for sustainability as well as acceptance among trauma/orthopedic surgeons. METHODS: For a 1-year period a prospective BMD test was carried out in women older than 50 and men older than 75 years of age with fractures. The commencement and conduction of therapy during the initial hospital stay and rehabilitation were also analyzed. RESULTS: From 228 members of the eligible age groups, 169 patients (74.1%) underwent BMD measurement. According to the WHO definition 71.6% showed reduced BMD in terms of osteoporosis and 24.3% in terms of osteopenia. In 84% therapy was started during initial hospital stay in 74.4% conducted during rehabilitation. CONCLUSIONS: The vast majority of older patients exhibited reduced BMD as a substantial underlying cause of their fracture. A standardized clinical plan can help to identify and treat most patients with fragility fractures.

Transcatheter coil embolization of an aneurysm of the pancreatico-duodenal artery with occluded celiac trunk.

We report on a case of a wide-necked aneurysm of the pancreatico-duodenal artery with occlusion of the celiac trunk in an asymptomatic patient. The aneurysm was considered to be at high risk of rupture. Successful embolization after interdisciplinary consultation was followed with color-coded duplex ultrasound (CCDS) demonstrating significant flow reduction. Three weeks later CCDS and angiography demonstrated exclusion of the aneurysm and a patent arterial supply of the liver and spleen fed by superior mesenteric artery (SMA) collaterals. The patient has done well so far, without major adverse clinical events or evidence for tissue necrosis of the liver, pancreas or spleen. Discussion of the case and review of the literature indicate that transcatheter embolization is the therapy of choice even in complicated cases.

[Recommendations for the selection of storage media for archiving digital radiological image data based on the comparison of retrieval times at different PACS archive levels]. / Empfehlungen zur Medienwahl für die Archivierung radiologischer Bilddaten auf der Basis einer Analyse der Zugriffszeiten auf verschiedene PACS-Archivebenen.

PURPOSE: Recommendations for archiving digital radiological image data based on the comparison of retrieval times for different PACS archive levels. MATERIALS AND METHODS: For a large PACS installation (Agfa Impax, Release 4.1), image retrieval times for radiological standard examinations (chest radiographs with 2, MRI with 250, CT with 100 and 1000 images; n = 120, each) from hard disk array, magneto-optical disk (MOD), and magnetic tape archives (TAPE) were examined in high and low network traffic load. RESULTS: Even large CT examinations (1000 images) were available from hard disk arrays within 4.0 +/- 0.8 s, smaller studies within 1.8 +/- 0.3 s. Radiographic image retrieval from MOD (30 +/- 4.7 s) was more then 50 % faster than from TAPE. For typical cross-sectional studies, the velocity gain amounted to 19 %. For both technologies, no significant difference was found for large CT examinations (651 +/- 144 s). For high and low network traffic load scenarios, image retrieval times from hard disk, MOD, and TAPE archives increased by 87 %, 7 %, and 22 %, respectively. CONCLUSION: Hard disk arrays are specifically suited as departmental intermediate storage media because they allow fast access to current and previous examinations within a short time. Performance properties enable both MOD and TAPE systems to serve as long-term archives. However, MOD archives are less flexible in the expansion of storage capacity and at present the medium costs per memory unit are about 2 - 3 times higher than for tape archives. The use of existing MOD-archives may be adequate as intermediate archives. For new PACS installations or system expansions, however, it is recommended to combine a sufficiently large local data memory (RAID) with data storage on tape archives outside the radiological unit that can be used by other departments as well. Future development of hard disk prices will show whether archiving for the whole data retention period may be handled by RAID systems. In any case, prefetching problems and waiting periods for demanded pre-studies would not occur any more.