Philipp G. C. Begemann

Feasibility of 18F-Sodium Fluoride PET/CT for Imaging of Atherosclerotic Plaque

The aim of this study was to examine the prevalence, distribution, and topographic relationship of vascular 18F-sodium fluoride uptake and arterial calcification in major arteries. Methods: Image data obtained from 75 patients undergoing whole-body 18F-sodium fluoride PET/CT were evaluated retrospectively. Arterial radiotracer uptake and calcification were analyzed qualitatively and semiquantitatively. Results: 18F-sodium fluoride uptake was observed at 254 sites in 57 (76%) of the 75 study patients, and calcification was observed at 1,930 sites in 63 (84%) of the patients. Colocalization of radiotracer accumulation and calcification could be observed in 223 areas of uptake (88%). However, only 12% of all arterial calcification sites showed increased radiotracer uptake. Conclusion: Our data indicate the feasibility of 18F-sodium fluoride PET/CT for the imaging of mineral deposition in arterial wall alterations. 18F-sodium fluoride PET/CT may provide relevant information about the morphologic and functional properties of calcified plaque.

Evaluation of the deep venous system in patients with suspected pulmonary embolism with multi-detector CT: a prospective study in comparison to Doppler sonography.

Objective: This prospective study was done to evaluate the ability of indirect multidetector row CT venography (CTV) in detecting deep venous thrombosis of the pelvis and the thighs in comparison with Doppler sonography in patients with suspected pulmonary embolism (PE). Methods: Forty‐one patients with suspected PE were included, and CTV (collimation 4 × 2.5 mm, table feed 12.5 mm, 120 kV, eff. mAs 165) from the iliac crest to the knees was done after CT angiography (CTA) of the pulmonary arteries. Doppler sonography was performed within 24 hours. Applied radiation doses were estimated using the PC program WinDose. Results: PE was diagnosed in 20 patients with additional DVT in 11 patients. The CTV has a sensitivity of 100%, specificity of 96.6%, a positive and negative predictive value of 91.7% and 100%, respectively. The median cumulative effective dose for CTV was 8.26 mSv with a gonadal dose of 3.87 mSv. Changing the CTV protocol to a collimation of 4 × 5 mm with a 25 mm table feed could reduce the dose by approximately 11% (p < 0.05) to 7.25 mSv and 3.35 mSv, respectively. Conclusion: CTV is a safe and quick diagnostic tool for detecting DVT in patients with suspected PE. Due to the relevant increase in radiation dose, the indication has to be considered very carefully. Index Terms: deep venous thrombosis, pulmonary embolism, multi‐detector CT, Doppler sonography.

Value of multiplanar reformations (MPR) in multidetector CT (MDCT) of acute vertebral fractures: do we still have to read the transverse images?

Objective: To determine the value of multiplanar reformations (MPRs) in multidetector computed tomography (MDCT) diagnosis of acute vertebral fractures and to assess the necessity to read the whole set of transverse images. Methods: Retrospectively, 56 MDCT of 55 patients with acute vertebral fractures were included. The images were analyzed by two radiologists in a consensus procedure. First, the diagnosis was made exclusively from sagittal and coronal MPRs; secondly, the transverse images were analyzed with knowledge of the MPRs. Diagnostic accuracy is given as percentage. Image amounts were compared using the Wilcoxon test. Results: In 244 vertebral bodies, all 70 fractured vertebrae were diagnosed on reviewing MPRs only. There were no false positive cases. In 2/70 fractures, the anatomically exact diagnosis was complemented by reading the transverse images. Forty-two of 43 unstable fractures were diagnosed correctly on MPRs only. With preference of MPR reading, the total number of images to be analyzed could be reduced significantly (P < 0.01). Conclusion: Reading of MPRs alone is a feasible approach for correct assessment of vertebral fractures and classifying them into stable/unstable, if MPRs are done properly. Transverse images must be analyzed in complex fractures or uncertain findings.

Computerassistierte Verschraubung des hinteren Beckenrings

ZusammenfassungFragestellungComputerassistierte Verfahren sind in der Traumatologie von zunehmender Bedeutung. Als eine sinnvolle Indikation hat sich die iliosakrale Schraubeninsertion erwiesen, wobei bislang keine systematischen Untersuchungen dazu vorliegen, mit welchem Navigationsverfahren die besten Ergebnisse erzielt werden können. In einer experimentellen Untersuchung sollte die Praktikabilität eines für die Beckenchirurgie zugelassenen 3D-Bildwandlers für diese Indikation geprüft und mit bereits etablierten Navigationsverfahren verglichen werden.Material und MethodenDie Versuche wurden an 20 fixierten Humankadavern vorgenommen. Zur Durchführung der navigierten Prozedur wurde ein aktives optoelektronisches System verwendet. Die Verschraubung erfolgte perkutan in Rückenlage mit durchbohrten Spongiosaschrauben, wobei 4 Behandlungsgruppen gebildet wurden. Die postoperative Schnittbildgebung erfolgte mittels fluoroskopischem 3D-Scan und MSCT. Zielparameter der Untersuchung waren neben der Praktikabilität und Präzision der Verfahren die durchschnittliche Operations- und Durchleuchtungszeit pro instrumentierter Schraube.ErgebnisseAlle navigierten Verfahren führten im Vergleich zur konventionellen Technik zu einer Verlängerung der Operationszeit (2D: p<0,001, 3D: p>0,05, CT: p<0,001). Gleichzeitig wurde die intraoperative Durchleuchtungszeit bei Anwendung aller navigierten Verfahren signifikant gesenkt (p<0,001). Die Fehlplatzierungsrate betrug bei der konventionellen und der 2D-fluoroskopisch navigierten Verschraubung jeweils 20%, die Verfahren mit dreidimensionaler (3D-)Bilddarstellung blieben jeweils ohne Implantatfehllagen (p>0,05). Die CT-Navigation erwies sich für die untersuchte Indikation aufgrund des störanfälligen Registrierungsvorgangs und der häufig unzureichenden Matchingpräzision allerdings nur als bedingt geeignet.SchlussfolgerungenUnsere Daten zeigen, dass die fluoroskopisch navigierte Verschraubung des hinteren Beckenrings gegenüber der CT-Navigation hinsichtlich Praktikabilität und logistischem Aufwand eindeutige Vorteile aufweist. Beide bildwandlergestützten Navigationsverfahren senken darüber hinaus die intraoperative Strahlenbelastung im Vergleich zur konventionellen Technik. Eine verbesserte Präzision der Schraubenplatzierung kann eher durch Verwendung eines 3D-Bildwandlers erreicht werden, mit dem darüber hinaus die Schraubenplatzierung noch intraoperativ zuverlässig beurteilt werden kann.AbstractObjectiveComputer-assisted procedures have recently been introduced for navigated iliosacral screw placement. Currently there are only few data available reflecting results and outcome of the different navigated procedures which may be used for this indication. We therefore evaluated the features of a new 3D image intensifier used for navigated iliosacral screw placement compared to 2D fluoroscopic and CT navigation.Materials and methodsTwenty fixed human cadavers were used in this trial. Cannulated cancellous screws were percutaneously implanted in the supine position in four treatment groups. An optoelectronic system was used for the navigated procedures. Screw placement was postoperatively assessed by fluoroscopic 3D scan and CT. The target parameters of this investigation were practicability, precision as well as procedure and fluoroscopic time per screw.ResultsAll navigated procedures revealed a significant loss of time compared to non-navigated screw placement (2D: p<0.001, 3D: p>0.05, CT: p<0.001). Simultaneously a significant decrease of radiation exposure time was observed in the navigated groups (p<0.001 each). The misplacement rate was 20% in the non-navigated and the 2D fluoroscopic navigated group each. Procedures providing 3D imaging of the posterior pelvis did not produce any screw misplacement (p>0.05). However, the CT procedure was associated with time-consuming registration and high rates of failed matching procedures.ConclusionOur data show a clear benefit of using C-arm navigation for iliosacral screw placement compared with the CT-based procedure. While both fluoroscopy-based navigation procedures decrease intraoperative radiation exposure times, only 3D fluoroscopic navigation seems to improve the precision compared to non-navigated screw placement.

Intraoperative Cone-Beam Computed Tomography in Oral and Maxillofacial Surgery Using a C-Arm Prototype : First Clinical Experiences After Treatment of Zygomaticomaxillary Complex Fractures

PURPOSE To describe the first clinical applications of intraoperative cone-beam computed tomography with an integrated flat-panel detector in oral and maxillofacial surgery after surgical treatment of zygomaticomaxillary complex fractures PATIENTS AND METHODS Nine cone-beam computed tomography datasets of patients with zygomaticomaxillary complex fractures were intraoperatively acquired using a mobile isocentric C-arm (PowerMobil; Siemens Medical Solutions, Erlangen, Germany), including a flat-panel detector. Datasets based on 400, 200, and 100 fluoroscopic images were performed with different tube currents (4.6 mA, 3.3 mA, 2.3 mA, 1.2 mA, and 0.5 mA) and a current tube voltage of 100 kV. Postprocessing resulted in 15 different datasets available for comparison with corresponding preoperative computed tomography datasets. Four oral and maxillofacial surgeons and 2 experienced radiologists evaluated each dataset regarding noise, transition, and the delimitation of landmarks. RESULTS All examinations were successfully performed. Reconstructed datasets showed high-resolution images of all midfacial osseous structures in near-computed tomography quality. Regarding high-contrast structures, detailed analyses of datasets acquired in this study suggest that the parameters 400 projections, 1.2 mA, and 100 kV are sufficient. In terms of soft-tissue visualization, a higher level of mA seems preferable. CONCLUSIONS The tested prototype predicts a new era in cone-beam computed tomography imaging. The integration of a flat-panel detector will overcome the limitations of current available systems. The size of the field of view is increased allowing regularly the visualization of the whole facial skeleton. Particularly in cases of open reduction of unilateral fractures, the assessment of symmetry is of clinical value.

[Computer-assisted screw placement into the posterior pelvic ring: assessment of different navigated procedures in a cadaver trial].

ZusammenfassungFragestellungComputerassistierte Verfahren sind in der Traumatologie von zunehmender Bedeutung. Als eine sinnvolle Indikation hat sich die iliosakrale Schraubeninsertion erwiesen, wobei bislang keine systematischen Untersuchungen dazu vorliegen, mit welchem Navigationsverfahren die besten Ergebnisse erzielt werden können. In einer experimentellen Untersuchung sollte die Praktikabilität eines für die Beckenchirurgie zugelassenen 3D-Bildwandlers für diese Indikation geprüft und mit bereits etablierten Navigationsverfahren verglichen werden.Material und MethodenDie Versuche wurden an 20 fixierten Humankadavern vorgenommen. Zur Durchführung der navigierten Prozedur wurde ein aktives optoelektronisches System verwendet. Die Verschraubung erfolgte perkutan in Rückenlage mit durchbohrten Spongiosaschrauben, wobei 4 Behandlungsgruppen gebildet wurden. Die postoperative Schnittbildgebung erfolgte mittels fluoroskopischem 3D-Scan und MSCT. Zielparameter der Untersuchung waren neben der Praktikabilität und Präzision der Verfahren die durchschnittliche Operations- und Durchleuchtungszeit pro instrumentierter Schraube.ErgebnisseAlle navigierten Verfahren führten im Vergleich zur konventionellen Technik zu einer Verlängerung der Operationszeit (2D: p<0,001, 3D: p>0,05, CT: p<0,001). Gleichzeitig wurde die intraoperative Durchleuchtungszeit bei Anwendung aller navigierten Verfahren signifikant gesenkt (p<0,001). Die Fehlplatzierungsrate betrug bei der konventionellen und der 2D-fluoroskopisch navigierten Verschraubung jeweils 20%, die Verfahren mit dreidimensionaler (3D-)Bilddarstellung blieben jeweils ohne Implantatfehllagen (p>0,05). Die CT-Navigation erwies sich für die untersuchte Indikation aufgrund des störanfälligen Registrierungsvorgangs und der häufig unzureichenden Matchingpräzision allerdings nur als bedingt geeignet.SchlussfolgerungenUnsere Daten zeigen, dass die fluoroskopisch navigierte Verschraubung des hinteren Beckenrings gegenüber der CT-Navigation hinsichtlich Praktikabilität und logistischem Aufwand eindeutige Vorteile aufweist. Beide bildwandlergestützten Navigationsverfahren senken darüber hinaus die intraoperative Strahlenbelastung im Vergleich zur konventionellen Technik. Eine verbesserte Präzision der Schraubenplatzierung kann eher durch Verwendung eines 3D-Bildwandlers erreicht werden, mit dem darüber hinaus die Schraubenplatzierung noch intraoperativ zuverlässig beurteilt werden kann.AbstractObjectiveComputer-assisted procedures have recently been introduced for navigated iliosacral screw placement. Currently there are only few data available reflecting results and outcome of the different navigated procedures which may be used for this indication. We therefore evaluated the features of a new 3D image intensifier used for navigated iliosacral screw placement compared to 2D fluoroscopic and CT navigation.Materials and methodsTwenty fixed human cadavers were used in this trial. Cannulated cancellous screws were percutaneously implanted in the supine position in four treatment groups. An optoelectronic system was used for the navigated procedures. Screw placement was postoperatively assessed by fluoroscopic 3D scan and CT. The target parameters of this investigation were practicability, precision as well as procedure and fluoroscopic time per screw.ResultsAll navigated procedures revealed a significant loss of time compared to non-navigated screw placement (2D: p<0.001, 3D: p>0.05, CT: p<0.001). Simultaneously a significant decrease of radiation exposure time was observed in the navigated groups (p<0.001 each). The misplacement rate was 20% in the non-navigated and the 2D fluoroscopic navigated group each. Procedures providing 3D imaging of the posterior pelvis did not produce any screw misplacement (p>0.05). However, the CT procedure was associated with time-consuming registration and high rates of failed matching procedures.ConclusionOur data show a clear benefit of using C-arm navigation for iliosacral screw placement compared with the CT-based procedure. While both fluoroscopy-based navigation procedures decrease intraoperative radiation exposure times, only 3D fluoroscopic navigation seems to improve the precision compared to non-navigated screw placement.

Multislice computed tomography-urography: intraindividual comparison of different preparation techniques for optimized depiction of the upper urinary tract in an animal model.

Objectives:We sought to evaluate intraindividually 3 different preparation protocols for achieving improved opacification and anatomic depiction of the upper urinary tract in multisclice computed tomography urography (MSCTU) using a porcine model. Material and Methods:MSCTU was performed in 8 healthy pigs. Each animal underwent 3 MSCT urographies using 3 different preparations before the injection of contrast material: A, intravenous (iv) saline (250 mL); B, iv low-dose furosemide (0.1 mg/kg); and C, iv saline (250 mL) plus iv low-dose furosemide (0.1 mg/kg). Image analysis was performed blinded to the applied protocols and included the evaluation of the opacification and anatomic depiction of the upper urinary tract by means of graded scales. Ureteral distension was determined and density was measured within the collecting system. Results:Furosemide significantly improved both mean opacification scores and mean scores of anatomic depiction compared with the exclusive infusion of saline for MSCTU. There was no significant difference between the application of furosemide and the combination of furosemide plus saline. A significant increase of 25–26% for ureteral distension was found when furosemide was applied. Significant lower mean attenuation values (Hounsfield units) and standard deviation were found within the opacified urine for diuretic-enhanced MSCTU. Conlusions:Low-dose furosemide injection is superior to saline infusion for achieving optimal enhancement in MSCTU. It is not necessary to combine furosemide and saline infusion. In MSCTU, low-dose furosemide is a simple add-on simplifying image acquisition timing and removing the need for abdominal compression devices.

Reducing CT radiation dose with iterative reconstruction algorithms: the influence of scan and reconstruction parameters on image quality and CTDIvol.

OBJECTIVES In this phantom CT study, we investigated whether images reconstructed using filtered back projection (FBP) and iterative reconstruction (IR) with reduced tube voltage and current have equivalent quality. We evaluated the effects of different acquisition and reconstruction parameter settings on image quality and radiation doses. Additionally, patient CT studies were evaluated to confirm our phantom results. METHODS Helical and axial 256 multi-slice computed tomography scans of the phantom (Catphan(®)) were performed with varying tube voltages (80-140kV) and currents (30-200mAs). 198 phantom data sets were reconstructed applying FBP and IR with increasing iterations, and soft and sharp kernels. Further, 25 chest and abdomen CT scans, performed with high and low exposure per patient, were reconstructed with IR and FBP. Two independent observers evaluated image quality and radiation doses of both phantom and patient scans. RESULTS In phantom scans, noise reduction was significantly improved using IR with increasing iterations, independent from tissue, scan-mode, tube-voltage, current, and kernel. IR did not affect high-contrast resolution. Low-contrast resolution was also not negatively affected, but improved in scans with doses <5mGy, although object detectability generally decreased with the lowering of exposure. At comparable image quality levels, CTDIvol was reduced by 26-50% using IR. In patients, applying IR vs. FBP resulted in good to excellent image quality, while tube voltage and current settings could be significantly decreased. CONCLUSIONS Our phantom experiments demonstrate that image quality levels of FBP reconstructions can also be achieved at lower tube voltages and tube currents when applying IR. Our findings could be confirmed in patients revealing the potential of IR to significantly reduce CT radiation doses.

[Injury pattern and clinical course of children with multiple injuries in comparison to adults, Ab 11-year analysis at a clinic of maximum utilization].

ZusammenfassungAufgrund der zumeist sehr kleinen Fallzahlen kindlicher Polytraumen in Einzelkliniken finden sich in der Literatur nur wenige Arbeiten, die mehrfachverletzte Kinder und Erwachsene miteinander vergleichen. Die Unterschiede dieser Patienten in Bezug auf Unfallart, Verletzungsmuster und pathophysiologische Eigenarten können den klinischen Verlauf jedoch maßgeblich beeinflussen und sind damit wichtig für das Behandlungsregime.In dieser Arbeit werden Daten zur Epidemiologie, präklinischen Versorgung, dem klinischen Verlauf und zu Komplikationen von polytraumatisierten Kindern und Erwachsenen erhoben. Das Ziel war es, auffällige Unterschiede zwischen den Kollektiven aufzuzeigen und mit der aktuellen Literatur zu vergleichen.Die meisten Unfälle ereignen sich im Straßenverkehr (Kinder 77,8%, Erwachsene 62,6%). Kinder werden häufiger mit dem RTH transportiert als Erwachsene. In beiden Altersgruppen überwiegen Kopfverletzungen und Verletzungen der Extremitäten. Erwachsene werden durchschnittlich länger beatmet als Kinder und die Aufenthaltsdauer auf der Intensiv- und Normalstation ist deutlich protrahiert.AbstractDue to the small number of polytraumatized children treated in single clinics, only a few studies are available that compare multiply injured children and adults.However, the differences between the two groups with respect to type of injury, injury patterns and pathophysiology may have some crucial effect on the clinical course and are therefore essential for the treatment regime.In this study data about the epidemiology, the preclinical treatment, the clinical course and the complication rates of polytraumatized children and adults were analysed. The aim of this study was to point out the main differences between the two collectives and to compare the results with the current literature.Traffic accidents were the leading cause for trauma (children 77.8%, adults 62.6%). Children more often were transported by helicopter than adults. In both age groups head injuries and fractures of the extremities were most frequent. Adults had a prolonged ventilation time as well as an increased stay in ICU and a regular ward.

Verletzungsmuster und klinischer Verlauf polytraumatisierter Kinder im Vergleich mit Erwachsenen

ZusammenfassungAufgrund der zumeist sehr kleinen Fallzahlen kindlicher Polytraumen in Einzelkliniken finden sich in der Literatur nur wenige Arbeiten, die mehrfachverletzte Kinder und Erwachsene miteinander vergleichen. Die Unterschiede dieser Patienten in Bezug auf Unfallart, Verletzungsmuster und pathophysiologische Eigenarten können den klinischen Verlauf jedoch maßgeblich beeinflussen und sind damit wichtig für das Behandlungsregime.In dieser Arbeit werden Daten zur Epidemiologie, präklinischen Versorgung, dem klinischen Verlauf und zu Komplikationen von polytraumatisierten Kindern und Erwachsenen erhoben. Das Ziel war es, auffällige Unterschiede zwischen den Kollektiven aufzuzeigen und mit der aktuellen Literatur zu vergleichen.Die meisten Unfälle ereignen sich im Straßenverkehr (Kinder 77,8%, Erwachsene 62,6%). Kinder werden häufiger mit dem RTH transportiert als Erwachsene. In beiden Altersgruppen überwiegen Kopfverletzungen und Verletzungen der Extremitäten. Erwachsene werden durchschnittlich länger beatmet als Kinder und die Aufenthaltsdauer auf der Intensiv- und Normalstation ist deutlich protrahiert.AbstractDue to the small number of polytraumatized children treated in single clinics, only a few studies are available that compare multiply injured children and adults.However, the differences between the two groups with respect to type of injury, injury patterns and pathophysiology may have some crucial effect on the clinical course and are therefore essential for the treatment regime.In this study data about the epidemiology, the preclinical treatment, the clinical course and the complication rates of polytraumatized children and adults were analysed. The aim of this study was to point out the main differences between the two collectives and to compare the results with the current literature.Traffic accidents were the leading cause for trauma (children 77.8%, adults 62.6%). Children more often were transported by helicopter than adults. In both age groups head injuries and fractures of the extremities were most frequent. Adults had a prolonged ventilation time as well as an increased stay in ICU and a regular ward.