Axel Thalhammer

MR-compatible Assistance System for Biopsy in a High-Field-Strength System: Initial Results in Patients with Suspicious Prostate Lesions

PURPOSE To examine the feasibility and safety of magnetic resonance (MR)-guided biopsy by using a transgluteal approach in patients with suspicious prostate lesions by using an MR-compatible robotic system and a 1.5-T MR system. MATERIALS AND METHODS The study was approved by the institutional review board of University Frankfurt, and informed consent was obtained from each patient. A total of 20 patients (age range, 57.8-71.9 years; mean age, 65.1 years) underwent biopsy in a closed-bore high-field-strength MR system. Biopsy was performed with an MR-compatible pneumatically driven robotic system. T1-weighted gradient-echo fast low-angle shot and T2-weighted true fast imaging with steady-state precession sequences were used to plan and guide the intervention with a transgluteal access on the external planning computer of the assistance system. The system calculated the trajectory and then moved the guiding arm to the insertion point. The cannula was advanced manually, and biopsies were performed with the coaxial technique by using a 15-gauge pencil tip needle. Intervention time, complications, and biopsy findings were documented. RESULTS The MR-compatible robotic system did not interfere with image quality, nor did MR imaging cause dysfunction of the robot. In one patient, the interventionist caused a fail-safe system shutdown. This was due to inadvertent displacement of the guiding arm during cannula insertion. This problem was solved by increasing the displacement threshold. Accurate coaxial cannula biopsy could be performed in all subsequent patients. Sufficient histopathologic assessment was performed in 19 patients. Insufficient material was retrieved in the patient who experienced fail-safe system shutdown. The median intervention time was 39 minutes (23-65 minutes). No procedure-related complications were observed. CONCLUSION Preliminary results indicate that MR-guided robot-assisted biopsy is feasible and can be performed safely with highly accurate cannula placement.

Traumatic injuries of the pelvis and thoracic and lumbar spine: does thin-slice multidetector-row CT increase diagnostic accuracy?

The objective is to evaluate different multidetector-row CT (MDCT) strategies for adequate classification of spinal and pelvic injuries. Seventy intubated patients after multiple trauma underwent conventional radiography (CR) and MDCT. Examinations included the pelvis (P), the lumbar spine (LS) and the thoracic spine (TS). Conventional radiographs, 3-mm (CT5) and 5-mm scans (CT3) and 3-mm and 5-mm scans combined with MPR (CT3R/CT5R) were compared to surgery, autopsy and clinical course. MDCT led to significantly better results than CR (P<0.01). Correlation coefficients were r=1.0 (CT3R), r=0.96 [TS] to r=1.0 [P/LS] (CT5R), r=0.8 [P] to r=1.0 [TS] (CT3), r=0.80 [P] to r=0.86 [TS] (CT5) and r=0.3 [TS] to r=0.69 [P] (CR). Fractures were identified by CT3R in 100% of cases, by CT5R in 95%, by CT3 in 90% [P]−100% [TS], by CT5 in 83.3% [LS]−90% [P] and by CR in 57.1% [TS]−87.2% [P]. Unstable fractures were identified in 100% by CT3R, CT5R and CT3, 85.7% [TS]−100% [P/LS] by CT5 and 57.1% [TS]−80% [P] by CR. Only overlapping thin-slice multiplanar reformation allows for an adequate classification of spinal and pelvic injuries and thus is highly emphasized in patients after severe blunt trauma.

Interstitial photodynamic laser therapy in interventional oncology

Photodynamic therapy (PDT) is a well-investigated locoregional cancer treatment in which a systemically administered photosensitizer is activated locally by illuminating the diseased tissue with light of a suitable wavelength. PDT offers various treatment strategies in oncology, especially palliative ones. This article focuses on the development and evaluation of interstitial PDT for the treatment of solid tumors, particularly liver tumors. The PDT is mostly used for superficial and endoluminal lesions like skin or bladder malignancies and also more frequently applied for the treatment of lung, esophageal, and head and neck cancer. With the help of specially designed application systems, PDT is now becoming a practicable option for solid lesions, including those in parenchymal organs such as the liver. After intravenous treatment with the photosensitizer followed by interstitial light activation, contrast-enhanced computed tomography shows the development of therapy-induced necrosis around the light-guiding device. With the use of multiple devices, ablation of liver tumors seems to be possible, and no severe side effects or toxicities related to the treatment are reported. PDT can become a clinically relevant adjunct in the locoregional therapy strategies.

Performance of iterative image reconstruction in CT of the paranasal sinuses: a phantom study.

BACKGROUND AND PURPOSE: CT in low dose technique is the criterion standard imaging modality for evaluation of the paranasal sinus. Our aim was to evaluate the dose-reduction potential of a recently available sinogram-affirmed iterative reconstruction technique, regarding noise, image quality, and time duration when evaluating this region. MATERIALS AND METHODS: CT was performed on a phantom head at different tube voltages (120 kV, 100 kV) and currents (100 mAs, 50 mAs, 25 mAs). Each protocol was reconstructed (in soft tissue and bony kernel) by using standard filtered back-projection and 5 different SAFIRE strengths, and image noise was evaluated. Subjective image quality was evaluated on noise-aligned image triplets acquired at tube currents of 100% (FBP), 50% (SAFIRE), and 25% (SAFIRE) by using a 5-point scale (1 = worst, 5 = best). The time duration for image reconstruction was noted for calculations with FBP and SAFIRE. RESULTS: SAFIRE reduced image noise by 15%–85%, depending on the iterative strength, rendering kernel, and dose parameters. Noise reduction was stronger at a bone kernel algorithm both in 1- and 3-mm images (P < .05). Subjective quality evaluation of the noise-adapted images showed preference for those acquired at 100% tube current with FBP (4.7–5.0) versus 50% dose with SAFIRE (3.4–4.4) versus 25% dose with SAFIRE (2.0–3.1). The time duration for FBP image sets was 2.9–6.6 images per second versus SAFIRE with 0.9–1.6 images per second. CONCLUSIONS: For CT of the paranasal sinus, SAFIRE algorithms are suitable for image-noise reduction. Because image quality decreases with dosage, careful choice of the appropriate iterative method is necessary to achieve an optimal balance between image noise and quality.

Pulmonary lymphangioleiomyomatosis: high-resolution CT findings.

Abstract. Lymphangioleiomyomatosis (LAM) of the lung is a very rare disease. There are obvious discrepancies in the literature concerning the appearance of LAM on CT scans of the lung. This study adds the imaging findings of 11 patients and demonstrates how the imaging findings changed over time in four patients. Twenty-two CT examinations, and radiographs that had been obtained close to the CT examinations, of 11 patients with LAM confirmed by open lung biopsy were retrospectively evaluated with particular attention to the size of cystic lesions and wall thickness. Furthermore the CT scans were analysed for the type of pulmonary infiltration process and its distribution, presence or absence of pleural effusion, pneumothorax and lymph node enlargement. Clinical and CT follow-up studies were available in four patients. The CT scans revealed an increase in the interstitial pattern in all patients. Architectural distortion was seen in two patients and cystic lesions were present in all. The size of the cysts varied from small lesions to bullous emphysema. The cystic lesions revealed a wall thickness up to 2 mm but a wall was not perceptible in all. Pneumothorax was seen in only two patients; pleural effusion was seen in two patients. CT examination of patients with LAM reveals neither a uniform nor a pathognomonic appearance. In the early stages of LAM or in cases with interstitial changes the differential diagnosis of centrilobular emphysema or idiopathic pulmonary fibrosis seems to be more difficult than most authors believe.

Value of a laser guidance system for CT interventions: a phantom study

Abstract. The aim of this study was to check the handling and usefulness of a laser puncture system. The laser has tacking optics and is fastened to a sledge with angle graduation. The sledge runs on a bar fixed to the computerized tomograph (CT) parallel to the scan level. By means of a phantom, three experienced and seven inexperienced physicians made punctures with and without laser, using varying angles in single and double angulation. The distance from needle tip to target was measured. The handling of the puncture system proved to be problem-free. With both single and double angulation, the measurement differences with and without support were so small among experienced puncturers that there was no significant difference, with the exception of one double angulation (10 °/45 °). Among the beginners, there was a significant difference (P < 0.001, P < 0.05), with both single and double angulation. The accuracy of the beginners improved with use of the laser; experienced puncturers may profit from practice with small and hard-to-reach focuses. In terms of educational benefits, the laser guidance system offers great advantages and increased confidence for beginners.

Radiation exposure to operating staff during rotational flat-panel angiography and C-arm cone beam computed tomography (CT) applications

PURPOSE To evaluate the radiation exposure for operating personnel associated with rotational flat-panel angiography and C-arm cone beam CT. MATERIALS AND METHODS Using a dedicated angiography-suite, 2D and 3D examinations of the liver were performed on a phantom to generate scattered radiation. Exposure was measured with a dosimeter at predefined heights (eye, thyroid, breast, gonads and knee) at the physicians location. Analysis included 3D procedures with a field of view (FOV) of 24 cm × 18 cm (8s/rotation, 20s/rotation and 5s/2 rotations), and 47 cm×18 cm (16s/2 rotations) and standard 2D angiography (10s, FOV 24 cm×18 cm). RESULTS Measurements showed the highest radiation dose at the eye and thyroid level. In comparison to 2D-DSA (3.9 μSv eye-exposure), the 3D procedures caused an increased radiation exposure both in standard FOV (8s/rotation: 28.0 μSv, 20s/rotation: 79.3 μSv, 5s/2 rotations: 32.5 μSv) and large FOV (37.6 μSv). Proportional distributions were measured for the residual heights. With the use of lead glass, irradiation of the eye lens was reduced to 0.2 μSv (2D DSA) and 10.6 μSv (3D technique with 20s/rotation). CONCLUSION Rotational flat-panel angiography and C-arm cone beam applications significantly increase radiation exposure to the attending operator in comparison to 2D angiography. Our study indicates that the physician should wear protective devices and leave the examination room when performing 3D examinations.

Older patients with high-risk fungal infections can be successfully allografted using non-myeloablative conditioning in combination with intensified supportive care regimens

Leukaemic patients with advanced disease and severe fungal infections as well as older patients with substantial co‐morbidity are usually excluded from conventional allotransplantation because of increased morbidity and mortality. We approached allogeneic transplantation in four patients with a median age of 62 years (one chronic myeloid leukaemia in blast crisis, one high‐risk acute myeloid leukaemia (AML) in first complete remission (CR1), one AML in 2nd relapse, one AML in CR2 with pre‐existing fungal lung infections (two aspergillus, two mucor) and additional co‐morbidity (diabetes n = 2, aortic aneurysm n = 1, arterial sclerosis n = 2) by combining non‐myeloablative conditioning with an intensified supportive care regimen, including amphotericin B and 4–12 (median 9) prophylactic granulocyte transfusions from granulocyte colony‐stimulating factor (G‐CSF)‐stimulated volunteer donors. G‐CSF was also given to patients until neutrophil recovery. All four patients recovered to a neutrophil count of 0·5 × 109/l after a median of 11·5 d (range 11–13 d). Prophylactic granulocyte transfusions also reduced the need for platelet transfusions and minimized mucositis. All patients were discharged at a median of 25 d (range 18–59 d) and are alive and well after a median follow‐up of > 390 d (range 336–417 d) without evidence of leukaemia. Regression of the fungal lesions was documented in three patients, with a slight progression detected by computerized tomography scan of the chest in one patient. We conclude that pulmonary fungal infections are not a contraindication for allogeneic stem cell transplantation, if non‐myeloablative conditioning regimens are used in combination with granulocyte transfusions, intravenous amphotericin B and G‐CSF.

Angioplasty of the pelvic and femoral arteries in PAOD: results and review of the literature.

PURPOSE Evaluation of percutaneous recanalization of obstructed iliac as well as superficial femoral arteries (SFAs) in patients with peripheral arterial obstructive disease (PAOD). MATERIAL AND METHODS The data of 195 consecutive patients with 285 obstructions of the common and or external iliac artery as well as the data of 452 consecutive patients with 602 long occlusions (length>5 cm) of the SFA were retrospectively analyzed. The lesions were either treated with percutaneous transluminal angioplasty (PTA) or Excimer laser assisted percutaneous transluminal angioplasty (LPTA). Overall 316 stents were implanted (Nitinol stents: 136; stainless steel stents: 180) in the iliac artery and 669 stents were implanted (Nitinol stents: 311; Easy Wallstents: 358) in the SFA. The follow-up period was 36-65 months (mean 46.98+/-7.11 months) postinterventionally using clinical examination, ABI calculation, and color-coded duplex sonography. Patency rates were calculated on the basis of the Kaplan-Meier analysis. RESULTS The overall primary technical success rate was 97.89% for the iliac arteries and 92.35% for the SFA. Minor complications (hematoma, distal emboli and vessel dissection) were documented in 11.79% for the iliac arteries and 7.97% for the SFA. The primary patency rate was 90.3% for the iliac and 52.8% for the SFA after 4 years. The secondary patency rate was 96.84% for the iliac and 77.8% for the SFA after 4 years. CONCLUSION Percutaneous recanalization of iliac and superficial femoral artery obstructions is a safe and effective technique for the treatment of patients with PAOD. By consequent clinical monitoring high secondary patency rates can be achieved. The use of a stents seems to result in higher patency rate especially in the SFA when compared to the literature in long-term follow-up.

Roboterunterstützte Punktion in einem Hochfeld-Kernspintomografen – erste klinische Ergebnisse

PURPOSE The purpose of this study was to examine the clinical use of MR-guided biopsies in patients with suspicious lesions using a new MR-compatible assistance system in a high-field MR system. MATERIALS AND METHODS Six patients with suspicious focal lesions in various anatomic regions underwent percutanous biopsy in a high-field MR system (1.5 T, Magnetom Espree, Siemens) using a new MR-compatible assistance system (Innomotion). The procedures were planned and guided using T 1-weighted FLASH and TrueFISP sequences. A servopneumatic drive then moved the guiding arm automatically to the insertion point. An MRI compatible 15G biopsy system (Somatex) was introduced by a physician guided by the needle holder and multiple biopsies were performed using the coaxial technique. The feasibility, duration of the intervention and biopsy findings were analyzed. RESULTS The proposed new system allows accurate punctures in a high-field MR system. The assistance device did not interfere with the image quality, and guided the needle virtually exactly as planned. Histological examination could be conducted on every patient. The lesion was malignant in four cases, and an infectious etiology was diagnosed for the two remaining lesions. Regarding the differentiation of anatomical and pathological structures and position monitoring of the insertion needle, TrueFISP images are to be given preference. The average intervention time was 41 minutes. Lesions up to 15.4 cm beneath the skin surface were punctured. CONCLUSION The proposed MR-guided assistance system can be successfully utilized in a high-field MR system for accurate punctures of even deep lesions in various anatomic regions.