Florian Streitparth

The initial phase of fracture healing is specifically sensitive to mechanical conditions

Interfragmentary movements affect the quality and quantity of callus formation. The mounting plane of monolateral external fixators may give direction to those movements. Therefore, the aim of this study was to determine the influence of the fixator mounting plane on the process of fracture healing.

CT-Guided Interstitial Brachytherapy of Primary and Secondary Lung Malignancies

Background and Purpose:CT-guided interstitial brachytherapy of primary lung malignancies and pulmonary metastases represents a novel interventional technique, combining conventional high-dose-rate (HDR) iridium-192 (192Ir) brachytherapy with modern CT guidance for applicator positioning and computer-aided 3-D radiation treatment planning. The purpose of this study was to assess safety and efficacy of this technique.Patients and Methods:30 patients with 83 primary or secondary lung malignancies were recruited in a prospective nonrandomized trial (Table 1). After catheter positioning under CT fluoroscopy, a spiral CT was acquired for treatment planning (Figure 1). All but two patients received a defined single dose (coverage > 99%) of at least 20 Gy from a 192Ir source in HDR technique.Results:Adverse effects were nausea (n = 3, 6%), minor (n = 6, 12%) and one major pneumothorax (2%). Post intervention, no changes of vital capacity and forced expiratory volume could be detected. The median follow-up period was 9 months (1–21 months) with a local tumor control of 91% at 12 months (Figure 2).Conclusion:CT-guided interstitial brachytherapy proved to be safe and effective for the treatment of primary and secondary lung malignancies.Hintergrund und Ziel:Die CT-gesteuerte interstitielle Brachytherapie von primären Lungenmalignomen und Lungenmetastasen stellt eine weiterentwickelte interventionelle Technik dar, welche die konventionelle Hochdosisraten-(HDR)-Iridium-192-(192Ir-)Brachytherapie mittels moderner CT-Bildführung zur Applikatorpositionierung und computergestützter 3-D-Bestrahlungsplanung kombiniert. Ziel der Studie war die Analyse von Sicherheit und Effektivität dieses Verfahrens.Patienten und Methodik:30 Patienten mit 83 primären Lungenmalignomen oder pulmonalen Metastasen wurden in einer prospektiven, nicht randomisierten Phase-II-Studie behandelt (Tabelle 1). Nach Katheterpositionierung unter CT-Fluoroskopie erfolgte die Gewinnung eines 3-D-Datensatzes für die Bestrahlungsplanung (Abbildung 1). Alle Patienten bis auf zwei erhielten eine vorgeschriebene Einzeldosis (Abdeckung > 99%) von mindestens 20 Gy über eine 192Ir-Quelle in HDR-Technik.Ergebnisse:Minorkomplikationen waren Übelkeit (n = 3, 6%), diskreter (n = 6, 12%) sowie ein therapiebedürftiger Pneumothorax (2%). Postinterventionell ergaben sich keine Änderungen der Vitalkapazität oder des forcierten exspiratorischen Volumens. Die mediane Nachbeobachtungszeit betrug 9 Monate (1–21 Monate). Die lokale Tumorkontrolle lag nach 12 Monaten bei 91% (Abbildung 2).Schlussfolgerung:Die CT-gesteuerte interstitielle HDR-Brachytherapie stellt ein sicheres und effektives Verfahren zur Behandlung von primären Lungenmalignomen und pulmonalen Metastasen dar.

Detection and classification of different liver lesions: comparison of Gd-EOB-DTPA-enhanced MRI versus multiphasic spiral CT in a clinical single centre investigation.

OBJECTIVE To compare the diagnostic efficacy of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) vs. multidetector computed tomography (MDCT) for the detection and classification of focal liver lesions, differentiated also for lesion entity and size; a separate analysis of pre- and postcontrast images as well as T2-weighted MRI sequences of focal and exclusively solid lesions was integrated. METHODS Twenty-nine patients with 130 focal liver lesions underwent MDCT (64-detector-row; contrast medium iopromide; native, arterial, portalvenous, venous phase) and MRI (1.5-T; dynamic and tissue-specific phase 20 min after application of Gd-EOB-DTPA). Hepatic lesions were verified against a standard of reference (SOR). CT and MR images were independently analysed by four blinded radiologists on an ordinal 6-point-scale, determining lesion classification and diagnostic confidence. RESULTS Among 130 lesions, 68 were classified as malignant and 62 as benign by SOR. The detection of malignant and benign lesions differed significantly between combined and postcontrast MRI vs. MDCT; overall detection rate was 91.5% for combined MRI and 80.4% for combined MDCT (p<0.05). Considering all four readers together, combined MDCT achieved sensitivity of 66.2%, specificity of 79.0%, and diagnostic accuracy of 72.3%; combined MRI reached superior diagnostic efficacy: sensitivity 86.8%, specificity 94.4%, accuracy 90.4% (p<0.05). Differentiated for lesion size, in particular lesions <20mm revealed diagnostic benefit by MRI. Postcontrast MRI also achieved higher overall sensitivity, specificity, and accuracy compared to postcontrast MDCT for focal and exclusively solid liver lesions (p<0.05). CONCLUSION Combined and postcontrast Gd-EOB-DTPA-enhanced MRI provided significantly higher overall detection rate and diagnostic accuracy, including low inter-observer variability, compared to MDCT in a single centre study.

Detection and classification of contrast-enhancing masses by a fully automatic computer-assisted diagnosis system for breast MRI

To evaluate a fully automatic computer‐assisted diagnosis (CAD) method for breast magnetic resonance imaging (MRI), which considered dynamic as well as morphologic parameters and linked those to descriptions laid down in the Breast Imaging Reporting and Data System (BI‐RADS) MRI atlas.

Stair climbing results in more challenging patellofemoral contact mechanics and kinematics than walking at early knee flexion under physiological-like quadriceps loading

The mechanical environment during stair climbing has been associated with patellofemoral pain, but the contribution of loading to this condition is not clearly understood. It was hypothesized that the loading conditions during stair climbing induce higher patellofemoral pressures, a more lateral force distribution on the trochlea and a more lateral shift and tilt of the patella compared to walking at early knee flexion. Optical markers for kinematic measurements were attached to eight cadaveric knees, which were loaded with muscle forces at instances of walking and stair climbing cycles at 12 degrees and 30 degrees knee flexion. Contact mechanics were determined using a pressure sensitive film. At 12 degrees knee flexion, stair climbing loads resulted in higher peak pressure (p=0.012) than walking, more lateral force distribution (p=0.012) and more lateral tilt (p=0.012), whilst mean pressure (p=0.069) and contact area (p=0.123) were not significantly different. At 30 degrees knee flexion, although stair climbing compared to walking loads resulted in significantly higher patellofemoral mean (p=0.012) and peak pressures (p=0.012), contact area (p=0.025), as well as tilt (p=0.017), the medial-lateral force distribution (p=0.674) was not significantly different. No significant differences were observed in patellar shift between walking and stair climbing at either 12 degrees (p=0.093) or 30 degrees (p=0.575) knee flexion. Stair climbing thus leads to more challenging patellofemoral contact mechanics and kinematics than level walking at early knee flexion. The increase in patellofemoral pressure, lateral force distribution and lateral tilt during stair climbing provides a possible biomechanical explanation for the patellofemoral pain frequently experienced during this activity.

Relationship between fetal head station established using an open magnetic resonance imaging scanner and the angle of progression determined by transperineal ultrasound

We investigated the correlation between the angle of progression measured by transperineal ultrasound and fetal head station measured by open magnetic resonance imaging (MRI), the gold standard, in pregnant women at full term.

Multislice computed tomography using a triple-phase contrast protocol for preoperative assessment of hepatic tumor load in patients with hepatocellular carcinoma before liver transplantation.

For evaluation of triple‐phase multislice computed tomography (CT) for assessment of hepatocellular carcinoma (HCC) before liver transplantation. All HCC patients who underwent liver transplantation at our institution between 2001 and 2006 and had contrast‐enhanced abdominal 4‐/16‐slice CT [unenhanced, arterial (20 s delay), portal venous (40 s), and venous (80 s) scan] within 100 days before transplantation were enrolled retrospectively. CT data were reviewed by two observers. Results were correlated to histopathologic findings by means of a lesion‐by‐lesion evaluation. Thirty‐two patients with 76 HCC‐lesions were included. The lesion‐based sensitivity of observer 1 and 2 was 78% (59/76) and 83% (63/76) (false positives, n = 6 and n = 10). The sensitivity of observer 1/2 was 89%/95% for lesions >20 mm (n = 37), 94% for lesions 11–20 mm (n = 18), and 43%/53% for lesions <10 mm (n = 21). The mean detection rates of unenhanced, arterial, portal venous, and venous phase scans were 30%, 74%, 59%, and 40%. All detected lesions were visible on arterial and/or portal venous scans (arterial only, 24%; portal venous only, 9%). Arterial and portal venous phase scans are the strongest contributors to the high detection rate of triple‐phase multislice‐CT in HCC. However, the detection of small HCC measuring <10 mm and false positive findings remains a challenge.

Radiobiological restrictions and tolerance doses of repeated single-fraction hdr-irradiation of intersecting small liver volumes for recurrent hepatic metastases.

BackgroundTo assess radiobiological restrictions and tolerance doses as well as other toxic effects derived from repeated applications of single-fraction high dose rate irradiation of small liver volumes in clinical practice.MethodsTwenty patients with liver metastases were treated repeatedly (2 - 4 times) at identical or intersecting locations by CT-guided interstitial brachytherapy with varying time intervals. Magnetic resonance imaging using the hepatocyte selective contrast media Gd-BOPTA was performed before and after treatment to determine the volume of hepatocyte function loss (called pseudolesion), and the last acquired MRI data set was merged with the dose distributions of all administered brachytherapies. We calculated the BED (biologically equivalent dose for a single dose d = 2 Gy) for different α/β values (2, 3, 10, 20, 100) based on the linear-quadratic model and estimated the tolerance dose for liver parenchyma D90 as the BED exposing 90% of the pseudolesion in MRI.ResultsThe tolerance doses D90 after repeated brachytherapy sessions were found between 22 - 24 Gy and proved only slightly dependent on α/β in the clinically relevant range of α/β = 2 - 10 Gy. Variance analysis showed a significant dependency of D90 with respect to the intervals between the first irradiation and the MRI control (p < 0.05), and to the number of interventions. In addition, we observed a significant inverse correlation (p = 0.037) between D90 and the pseudolesions volume. No symptoms of liver dysfunction or other toxic effects such as abscess formation occurred during the follow-up time, neither acute nor on the long-term.ConclusionsInactivation of liver parenchyma occurs at a BED of approx. 22 - 24 Gy corresponding to a single dose of ~10 Gy (α/β ~ 5 Gy). This tolerance dose is consistent with the large potential to treat oligotopic and/or recurrent liver metastases by CT-guided HDR brachytherapy without radiation-induced liver disease (RILD). Repeated small volume irradiation may be applied safely within the limits of this study.

Obese patients in an open MRI at 1.0 Tesla: image quality, diagnostic impact and feasibility

ObjectiveTo investigate the performance of an open MRI system at its conceptual limits by examining excessively obese patients who otherwise could not receive adequate imaging examinations.MethodsTwenty-six excessively obese patients (BMI ≥ 35, average age 46) where CT, standard MR or ultrasound examinations were not possible or not conclusive were referred to an open MRI system at 1.0 Tesla. Image quality was measured by SNR and CNR with the integrated body coil for obese patients and optimal body coils for a regular weight control group (average BMI 23, average age 30). MRI findings were evaluated by a diagnostic impact matrix.ResultsSNR and CNR were generally lower in obese patients when the integrated body coil was used compared to the normal weight group with ideal body coils e.g.: For cerebral imaging T2W TSE (<5% for white matter, ca. 30% for grey matter) and T1W SE (ca. 15% for white matter, <5% for grey matter), for spinal imaging T2W TSE (ca. 35% for disc and vertebral body) and T1W SE (about 2% for disc, ca. 10% for vertebral body). Relevant new diagnoses impacting patient’s therapy were identified in 30% (8/26), the particular medical question of the referring physician could be ruled out as possible reason for the medical condition in 53% (14/26).ConclusionIn excessively obese patients where CT, standard MR or ultrasound examination is not possible or not conlusive open MRI system have great potential in diagnostic evaluation, offering lower but sufficient image quality to impact therapy.

Assessment of Local Control after Laser-Induced Thermotherapy of Liver Metastases from Colorectal Cancer: Contribution of FDG-PET in Patients with Clinical Suspicion of Progressive Disease

Background: Management of patients after locally ablative treatment of liver metastases requires exact information about local control and systemic disease status. To fulfill these requirements, whole-body imaging using positron emission tomography with 18F-fluorodeoxyglucose (FDG-PET) is a promising alternative to morphologic imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI). Purpose: To evaluate FDG-PET for the assessment of local control and systemic disease in patients with clinical suspicion of tumor progression after laser-induced thermotherapy (LITT) of colorectal liver metastases. Material and Methods: In 21 patients with suspicion of progressive disease after LITT, whole-body FDG-PET was performed. The presence of viable tumor within treated lesions, new liver metastases, and extrahepatic disease was evaluated visually and semiquantitatively (maximal standard uptake value [SUVmax], tumor-to-normal ratio [T/N]). The standard of reference was histopathology (n = 25 lesions) and/or clinical follow-up (>12 months) including contrast-enhanced MRI of the liver. Results: Among 54 metastases treated with LITT, 29 had residual tumor. Receiver operating characteristic (ROC) analysis of SUVmax (area under the curve (AUC) 0.990) and T/N (AUC 0.968) showed a significant discrimination level of negative or positive lesion status with an equal accuracy of 94% (51/54). The overall accuracy of visual FDG-PET was 96% (52/54), with one false-negative lesion among six examined within 3 days after LITT, and one false-positive lesion examined 54 days after LITT. In the detection of new intra- and extrahepatic lesions, FDG-PET resulted in correct alteration of treatment strategy in 43% of patients (P = 0.007). Conclusion: FDG-PET is a promising tool for the assessment of local control and whole-body restaging in patients with clinical suspicion of tumor progression after locally ablative treatment of colorectal liver metastases with LITT.