P. Mildenberger

Pneumonia in Febrile Neutropenic Patients and in Bone Marrow and Blood Stem-Cell Transplant Recipients: Use of High-Resolution Computed Tomography

PURPOSE To obtain statistical data on the use of high-resolution computed tomography (HRCT) for early detection of pneumonia in febrile neutropenic patients with unknown focus of infection. MATERIALS AND METHODS One hundred eighty-eight HRCT studies were performed prospectively in 112 neutropenic patients with fever of unknown origin persisting for more than 48 hours despite empiric antibiotic treatment. Fifty-four of these studies were performed in transplant recipients. All patients had normal chest roentgenograms. If pneumonia was detected by HRCT, guided bronchoalveolar lavage was recommended. Evidence of pneumonia on chest roentgenograms during follow-up and micro-organisms detected during follow-up were regarded as documentation of pneumonia. RESULTS Of the 188 HRCT studies, 112 (60%) showed pneumonia and 76 were normal. Documentation of pneumonia was possible in 61 cases by chest roentgenography or micro-organism detection (54%) (P < 10(-6)). Sensitivity of HRCT was 87% (88% in transplant recipients), specificity was 57% (67%), and the negative predictive value was 88% (97%). A time gain of 5 days was achieved by the additional use of HRCT compared to an exclusive use of chest roentgenography. CONCLUSION The high frequency of inflammatory pulmonary disease after a suspicious HRCT scan (> 50%) proves that pneumonia is not excluded by a normal chest roentgenogram. Given the significantly longer duration of febrile episodes in transplant recipients, HRCT findings are particularly relevant in this subgroup. Patients with normal HRCT scans, particularly transplant recipients, have a low risk of pneumonia during follow-up. All neutropenic patients with fever of unknown origin and normal chest roentgenograms should undergo HRCT.

Introduction to the DICOM standard

Abstract. Digital Imaging and Communication in Medicine (DICOM) has become one of the most popular standards in medicine. In the beginning, DICOM was used for communication of image data between different systems. Actual developments of the standardisation enables increasingly more DICOM-based services for the integration of modalities and information systems (e.g. RIS, PACS). In this article a review of the historical background, the technological concept, the organizational structure and current developments is given.

Computed tomographies and cancer risk in children: a literature overview of CT practices, risk estimations and an epidemiologic cohort study proposal.

Radiation protection is a topic of great public concern and of many scientific investigations, because ionizing radiation is an established risk factor for leukaemia and many solid tumours. Exposure of the public to ionizing radiation includes exposure to background radiation, as well as medical and occupational exposures. A large fraction of the exposure from diagnostic procedures comes from medical imaging. Computed tomography (CT) is the major single contributor of diagnostic radiation exposure. An increase in the use of CTs has been reported over the last decades in many countries. Children have smaller bodies and lower shielding capacities, factors that affect the individual organ doses due to medical imaging. Several risk models have been applied to estimate the cancer burden caused by ionizing radiation from CT. All models predict higher risks for cancer among children exposed to CT as compared to adults. However, the cancer risk associated with CT has not been assessed directly in epidemiological studies. Here, plans are described to conduct an historical cohort study to investigate the cancer incidence in paediatric patients exposed to CT before the age of 15 in Germany. Patients will be recruited from radiology departments of several hospitals. Their individual exposure will be recorded, and time-dependent cumulative organ doses will be calculated. Follow-up for cancer incidence via the German Childhood Cancer Registry will allow computation of standardized incidence ratios using population-based incidence rates for childhood cancer. Dose–response modelling and analyses for subgroups of children based on the indication for and the result of the CT will be performed.

Focal airtrapping at expiratory high-resolution CT: comparison with pulmonary function tests

Abstract. This study was undertaken to determine prevalence, extent, and severity of focal airtrapping at expiratory high-resolution CT, and to compare focal airtrapping with age, gender, pulmonary function tests, and blood gas analysis. Two-hundred seventeen patients with and without pulmonary disease underwent paired inspiratory/expiratory high-resolution CT. Six scan pairs with corresponding scan levels were visually assessed for focal – not diffuse – airtrapping using a four-point scale. Pulmonary function tests and blood gas analysis were available for correlation in all patients (mean interval 5 days). Focal airtrapping with lower lung predominance was observed in 80 % of patients. Twenty-six of 26 patients with restrictive lung function impairment exhibited focal airtrapping (mean score 2.4), whereas only 72 of 98 (74 %) patients with obstruction did (mean score 1.5; p < 0.05). Fifty-eight of 70 (83 %) patients with normal lung function (mean score 1.8) and 19 of 23 (83 %) patients with mixed impairment (mean score 1.8) had focal airtrapping. Focal airtrapping showed negative correlations with static lung volumes (–0.27 to –0.37; p < 0.001) in all patients and moderate positive correlations with dynamic parameters (0.3–0.4; p < 0.001) in patients with obstruction. No significant correlations were found with age, gender, and blood gas analysis. Visual assessment of focal – not diffuse – airtrapping at expiratory high-resolution CT does not correlate with physiological evidence of obstruction as derived from pulmonary function tests since the perception of focal airtrapping requires an adequate expiratory increase in lung density.

Detection of lymph node metastases in esophageal cancer

Lymph node status is the most important single prognostic factor in esophageal cancer. The detection of involved lymph nodes is therefore the key to cure. This article will provide a meta-analysis and metaregression analysis on the diagnostic performances of current lymph node-detection devices; discuss the recent status of the sentinel lymph node concept in esophageal cancer by the two sentinel node-mapping procedures (the radio-guided and the blue dye techniques) and the developing computed tomography (CT) lymphography; discuss the detection of micrometastases; and the potential clinical application of molecular-based patients’ profiles. Combined use of endoscopic ultrasonography fine-needle aspiration and CT significantly improves the diagnostic performance for regional lymph node metastases. Endoscopic ultrasonography is highly sensitive and specific for celiac lymph node metastases, while CT should mostly be performed in order to exclude other abdominal lymph node metastases. Sentinel lymph node navigation may be feasible for cT1N0 or cT2N0 esophageal cancer, and immunohistochemical staining of micrometastatic disease might be feasible in combination with this modality.

Assessment of tumor microcirculation with dynamic contrast-enhanced MRI in patients with esophageal cancer: Initial experience

To investigate the feasibility and impact of dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) on tumor characterization and response to radiochemotherapy (RCT) in patients with esophageal cancer.

Comparison of contrast-enhanced MR angiography to intraarterial digital subtraction angiography for evaluation of peripheral arterial occlusive disease: Results of a phase III multicenter trial

To evaluate the efficacy and safety of 0.1 mmol/kg gadodiamide administration for contrast‐enhanced magnetic resonance angiography (CE‐MRA) in detecting hemodynamically relevant main stenosis (ie, ≥50% or occlusion) of aortoiliac arteries.

Standardization of teleradiology using Dicom e-mail: recommendations of the German Radiology Society

Until recently there has been no standard for an interoperable and manufacturer-independent protocol for secure teleradiology connections. This was one of the main reasons for the limited use of teleradiology in Germany. Various teleradiology solutions have been developed in the past, but the vast majority have not been interoperable. Therefore an ad hoc teleradiology connection was impossible even between partners who were already equipped with teleradiology workstations. Based on the evaluation of vendor-independent protocols in recent years the IT Working Group (AGIT) of the German Radiology Society set up an initiative to standardize basic teleradiology. An e-mail based solution using the Dicom standard for e-mail attachments with additional encryption according to the OpenPGP standard was found to be the common denominator. This protocol is easy to implement and safe for personalized patient data and fulfills the legal requirements for teleradiology in Germany and other countries. The first version of the recommendation was presented at the 85th German Radiology Convention in 2004. Eight commercial and three open-source implementations of the protocol are currently available; the protocol is in daily use in over 50 hospitals and institutions.

Effectiveness of platinum wire microcoils for venous occlusion: A study on patients treated for venogenic impotence

The purpose of this study was to determine the effectiveness of venous occlusions achieved by embolization with platinum microwire coils. Follow-up venographies in 19 patients, 1–20 months (average 8 months) after coil embolizations, were evaluated. Twenty-eight of 126 (22.2%) coil embolizations were found to be patent. Coils which had not formed or partially formed upon embolization had a patency/recanalization rate of 37.5% (12/32). Among coils which had formed nearly completely or completely only 16 of 95 (17%) showed venous patency. As coil embolization had been augmented by sclerotherapy in all patients, the effectiveness of long-term venous occlusion by platinum wire coils alone is probably lower than our figures indicate. We conclude that attention to complete or near-complete coil formation upon embolization appears to be critical to maximize long-term occlusive effects of platinum microcoils. Their effectiveness in general, however, is lower than anticipated.

Aneurysms complicating inflammatory diseases in immunocompromised hosts: value of contrast-enhanced CT

Abstract. We studied the value of contrast-enhanced CT in the detection of aneurysms in immunocompromised patients suffering from inflammatory diseases eventually complicated by hemorrhage. Contrast-enhanced spiral CT was applied in three patients with immunocompromise due to chemotherapy, alcohol abuse or HIV. They suffered from invasive aspergillosis, chronic pancreatitis with pseudocyst formation, and acute pancreatitis together with HIV-associated lymphadenopathy. Complicating hemorrhage was present in two cases. Contrast-enhanced CT showed aneurysms complicating the underlying inflammatory disease in all three cases. The feeding vessels were identified and the patients with signs of bleeding were subsequently referred for angiography and embolization. Contrast-enhanced spiral CT is suited to detect aneurysms in immunocompromised patients suffering from inflammatory disease. It is recommended in these patients prior to angiography and intervention.