Ferdinand Kammerer

A Novel Pairwise Comparison-Based Method to Determine Radiation Dose Reduction Potentials of Iterative Reconstruction Algorithms, Exemplified Through Circle of Willis Computed Tomography Angiography.

ObjectivesThe aim of this study was to determine the dose reduction potential of iterative reconstruction (IR) algorithms in computed tomography angiography (CTA) of the circle of Willis using a novel method of evaluating the quality of radiation dose–reduced images. Materials and MethodsThis study relied on ReconCT, a proprietary reconstruction software that allows simulating CT scans acquired with reduced radiation dose based on the raw data of true scans. To evaluate the performance of ReconCT in this regard, a phantom study was performed to compare the image noise of true and simulated scans within simulated vessels of a head phantom. That followed, 10 patients scheduled for CTA of the circle of Willis were scanned according to our institutes standard protocol (100 kV, 145 reference mAs). Subsequently, CTA images of these patients were reconstructed as either a full-dose weighted filtered back projection or with radiation dose reductions down to 10% of the full-dose level and Sinogram-Affirmed Iterative Reconstruction (SAFIRE) with either strength 3 or 5. Images were marked with arrows pointing on vessels of different sizes, and image pairs were presented to observers. Five readers assessed image quality with 2-alternative forced choice comparisons. ResultsIn the phantom study, no significant differences were observed between the noise levels of simulated and true scans in filtered back projection, SAFIRE 3, and SAFIRE 5 reconstructions.The dose reduction potential for patient scans showed a strong dependence on IR strength as well as on the size of the vessel of interest. Thus, the potential radiation dose reductions ranged from 84.4% for the evaluation of great vessels reconstructed with SAFIRE 5 to 40.9% for the evaluation of small vessels reconstructed with SAFIRE 3. ConclusionsThis study provides a novel image quality evaluation method based on 2-alternative forced choice comparisons. In CTA of the circle of Willis, higher IR strengths and greater vessel sizes allowed higher degrees of radiation dose reduction.

Mobile Image Interpretation: Diagnostic Performance of CT Exams Displayed on a Tablet Computer in Detecting Abdominopelvic Hemorrhage

To investigate whether abdominopelvic hemorrhage shown on computed tomography (CT) images can be diagnosed with the same accuracy on a tablet computer as on a dedicated reading display. One hundred patients with a clinical suspicion of abdominopelvic hemorrhage that underwent biphasic CT imaging were retrospectively read by two readers on a dedicated reading display (reference standard) and on a tablet computer (iPad Air). Reading was performed in a dedicated reading room with ambient light conditions. Image evaluation included signs of an active hemorrhage (extravasation of contrast media) and different signs indicating a condition after abdominopelvic hemorrhage (hematoma, intestinal clots, vessel stump, free abdominopelvic fluid with a mean Hounsfield unit value >20, and asymmetric muscle volume indicating intramuscular hemorrhage). Sensitivity, specificity, and positive and negative predictive values (PPV/NPV) were calculated for the tablet-based reading. Active abdominopelvic hemorrhage (n = 72) was diagnosed with the tablet computer with a sensitivity of 0.96, a specificity of 0.93, a PPV of 0.97, and an NPV of 0.90. The results for the detection of the signs indicating a condition after abdominopelvic hemorrhage range from 0.83 to 1.00 in the case of sensitivity, from 0.95 to 1.00 in the case of specificity, from 0.94 to 1.00 in the case of the PPV, and from 0.96 to 1.00 in the case of the NPV. Abdominopelvic hemorrhage shown on CT images can be diagnosed on a tablet computer with a high diagnostic accuracy allowing mobile on-call diagnoses. This may be helpful because an early and reliable diagnosis at any time is crucial for an adequate treatment strategy.

Computed Tomography Angiography of Carotid Arteries and Vertebrobasilar System: A Simulation Study for Radiation Dose Reduction

AbstractComputed tomography angiography (CTA) of carotid arteries and vertebrobasilar system is a standardized procedure with excellent image quality, but radiation exposure remains a matter of concern. The aim of this study is to examine to what extent radiation dose can be lowered in relation to a standard protocol by simulating examinations with lower tube currents applying a dedicated software.Lower tube current was simulated by a dedicated noise insertion and reconstruction software (ReconCT). In a phantom study, true scans were performed with different dose protocols and compared to the results of simulated dose reductions of the same degree, respectively. In a patient study, 30 CTAs of supra-aortic vessels were reconstructed at a level of 100%, 75%, 50%, and 25% of the initial dose. Objective and subjective image analyses were performed.No significant noise differences between true scans and simulated scans of mimicked contrasted vessels were found. In the patient study, the quality scores of the 4 dose groups differed statistically significant; this difference vanished for the comparison of the 100% and 75% datasets after dichotomization into the categories of diagnostic and nondiagnostic image quality (P = .50).This study suggests an easy-to-implement method of simulating CTAs of carotid arteries and vertebrobasilar system with lower tube current for dose reduction by artificially adding noise to the original raw data. Lowering the radiation dose in a moderate extent to 75% of the original dose levels does not significantly alter the diagnostic image quality.

Practicability of Hygienic Wrapping of Touchscreen Operated Mobile Devices in a Clinical Setting

Background To prove effectiveness of wrapping tablet computers in order to reduce microbiological contamination and to evaluate whether a plastic bag-covered tablet leads to impaired user satisfaction or touchscreen functionality. Materials and Methods Within a period of 11 days 115 patients were provided with a tablet computer while waiting for their magnetic resonance imaging examination. Every day the contamination of the surface of the tablet was determined before the first and after the final use. Before the device was handed over to a patient, it was enclosed in a customized single-use plastic bag, which was analyzed for bacterial contamination after each use. A questionnaire was applied to determine whether the plastic bag impairs the user satisfaction and the functionality of the touchscreen. Results Following the use by patients the outside of the plastic bags was found to be contaminated with various bacteria (657.5 ± 368.5 colony forming units/day); some of them were potentially pathogenic. In contrast, the plastic bag covered surface of the tablet was significantly less contaminated (1.7 ± 1.9 colony forming units/day). Likewise, unused plastic bags did not show any contamination. 11% of the patients reported problems with the functionality of the touchscreen. These patients admitted that they had never used a tablet or a smartphone before. Conclusions Tablets get severely contaminated during usage in a clinical setting. Wrapping with a customized single-use plastic bag significantly reduces microbiological contamination of the device, protects patients from the acquisition of potentially pathogenic bacteria and hardly impairs the user satisfaction and the functionality of the touchscreen.

A web based cross-platform application for teleconsultation in radiology.

The growing complexity of radiologic examinations and interventional procedures requires frequent exchange of knowledge. Consequently a simple way to share and discuss patient images between radiology experts and with colleagues from other medical disciplines is needed. Aims of this work were the development and initial performance evaluation of a fast and user friendly, platform independent teleconsultation system for medical imaging. A local back end system receives DICOM images and generates anonymized JPEG files that are uploaded to an internet webserver. The front end running on that webserver comprises an image viewer with a specially developed pointer element for indicating findings to collaborative partners. The front end that uses only standard web technologies works on a variety of different platforms, mobile devices and desktop computers. Images can be accessed by simply calling up a special internet address in a web browser that may be exchanged between users (e.g. via email). A speed evaluation of the system showed good results: For example the preparation and upload of a standard head CT took less than 21 seconds. The data volume of the same series and the viewer application could be transferred to a mobile phone in less than 42 seconds via a UMTS network or in less than 3 seconds via a HSPA network. The presented system with its minimal hard- and software requirements, its simplicity and platform independence might be a promising tool in the increasingly important area of teleconsultation.

MyCases—A Portable Application for Radiologic Case Collections

Radiologists come across interesting patient cases almost every day. This work proposes a novel case database server for quick and easy storage of such cases including whole image series, patient data, and annotations. Cases can be added to the database by saving DICOM images into a predefined directory on the local network. The application automatically extracts patient and study data from the DICOM header and saves it in the database while images are stored as anonymized JPEG files. Users can mark their cases as private or public (visible to all users). Different data fields for annotations and categorization of a case are available. The user frontend also provides several retrieval mechanisms allowing for browsing the cases and performing different kinds of search queries. The stored series can be scrolled interactively in the form of scrollable image stacks. The project is realized as a web-based application using a portable web and database server software package (XAMPP). This makes the system very lightweight and easy to run on almost any desktop computer, even from a USB flash drive, without the need for deeper IT knowledge and administrative rights.

Metastatic insulinoma - prolonged survival after multimodal approach.

Summary Background Metastatic insulinoma is a disease associated with a poor life expectancy. Case Report The case of a presently 68 year old female with malignant, metastatic insulinoma is reported. Due to severe clinical symptoms surgical tumor mass reduction was conducted. Furthermore the patient underwent a chemotherapy using streptozotocine and fluorouracil. After two years without any symptoms, the remaining hepatic metastases increased in size and again hypoglycemias occurred. To reachieve an asymptomatic state and further reduction in tumor mass, the decision was made for transarterial chemoembolization with streptozotocine. After the first treatment the patient was hypoglycemia – free for 3 months, after another more extensive chemoembolization the patient is presently symptom free for 8 months. Conclusions Since the diagnosis of extended disease was established, the patient has survived for 36 months. We regard this as the result of a multimodal approach and the extensive use of local tumor therapy. The different therapeutic options for local tumor therapy are reported and discussed.

Advanced Modeled Iterative Reconstruction (ADMIRE) Facilitates Radiation Dose Reduction in Abdominal CT

RATIONALE AND OBJECTIVES This study aimed to determine the potential degree of radiation dose reduction achievable using Advanced Modeled Iterative Reconstruction (ADMIRE) in abdominal computed tomography (CT) while maintaining image quality. Moreover, this study compared differences in image noise reduction of this iterative algorithm with radiation dose reduction. METHODS Eleven consecutive patients scheduled for abdominal CT were scanned according to our institutes standard protocol (100 kV, 289 reference mAs). Using a proprietary reconstruction software, CT images of these patients were reconstructed as either full-dose weighted filtered back projections or with simulated radiation dose reductions down to 10% of the full-dose level and ADMIRE at either strength 3 or strength 5. Images were marked with arrows pointing on anatomic structures of the abdomen, differing in their contrast to the surrounding tissue. Structures were grouped into high-, medium-, and low-contrast subgroups. In addition, the intrinsic noise of these structures was measured. That followed, image pairs were presented to observers, with five readers assessing image quality using two-alternative-forced-choice comparisons. In total, 3000 comparisons were performed that way. RESULTS Both ADMIRE 3 and 5 decreased noise of the anatomic structures significantly compared to the filtered back projection, with an additional significant difference between ADMIRE 3 and 5. Radiation dose reduction potential for ADMIRE ranged from 29.0% to 53.5%, with no significant differences between ADMIRE 3 and 5 within the contrast subgroups.The potential levels of radiation dose reduction for ADMIRE 3 differed significantly between high-, medium-, and low-contrast structures, whereas for ADMIRE 5, there was only a significant difference between the high- and the medium-contrast subgroups. CONCLUSION Although ADMIRE 5 permits significantly higher noise reduction potential than ADMIRE 3, it does not facilitate higher levels of radiation dose reduction. ADMIRE nonetheless holds remarkable potential for radiation dose reduction, which features a certain dependency on the contrast of the structure of interest. Applying ADMIRE with a strength of 3 in abdominal CT may permit radiation dose reduction of about 30%.

Successful Multidisciplinary Treatment with Secondary Metastatic Liver Resection after Downsizing by Palliative Second-Line Treatment of Colorectal Cancer: A Curative Option

Introduction: The prognostic outcome following progression after palliative first-line treatment for patients suffering from metastatic colorectal adenocarcinoma is generally poor. Long-term relapse-free survival with palliative second-line treatment may be achieved in only a limited number of individual cases. Case Report: A 37-year-old patient presented with bilobar liver metastases of colon cancer confirmed by histology with wild-type K-RAS (exon 2). Due to progressive disease after eight cycles of first-line therapy with FOLFIRI plus cetuximab, second-line chemotherapy with modified FOLFOX4 (mFOLFOX4) plus bevacizumab was initiated. During four cycles of mFOLFOX4 plus bevacizumab (2 months), no higher-grade toxicity occurred. Liver MRI with contrast medium revealed downsizing of the segment II/III metastases, as well as regressive, small, faint, hardly definable lesions in segments VI and IVb. The interdisciplinary tumor board of the University of Erlangen thus decided to perform resection of the liver metastases. Segments II and III were resected, and the liver metastases in segments IVa and VI were excised (R0). Histopathology confirmed three of the R0-resected metastases to be completely necrotic, with residual scarring. As perioperative therapy, four additional cycles of mFOLFOX4 plus bevacizumab were administered postoperatively. No higher-grade toxicity was observed. Three years after the initial diagnosis, the patient is relapse free, professionally fully reintegrated, and has an excellent performance status. Conclusion: Patients suffering from metastatic colorectal cancer may benefit from multidisciplinary treatment with secondary metastatic liver resection after downsizing by palliative second-line treatment. In individual cases, patients may even have a curative treatment option, provided that close interdisciplinary collaboration exists.