Assessment of metastatic colorectal cancer with hybrid imaging: comparison of reading performance using different combinations of anatomical and functional imaging techniques in PET/MRI and PET/CT in a short case series.

PURPOSE: The purpose was to investigate the diagnostic performance of different combinations of anatomical and functional imaging techniques in PET/MRI and PET/CT for the evaluation of metastatic colorectal cancer lesions. METHODS: Image data of 15 colorectal cancer patients (FDG-PET/CT and subsequent FDG-PET/MRI) were retrospectively evaluated by two readers in five reading sessions: MRI (morphology) alone, MRI/diffusion-weighted MRI (DWI), MRI/PET, MRI/DWI/PET; and PET/CT. Diagnostic performance of lesion detection with each combination was assessed in general and organ-based. The reference standard was given by histology and/or follow-up imaging. Separate analysis of mucinous tumours was performed. RESULTS: One hundred and eighty lesions (110 malignant) were evaluated (intestine n = 6, liver n = 37, lymph nodes n = 55, lung n = 4, and peritoneal n = 74). The overall lesion-based diagnostic accuracy was 0.46 for MRI, 0.47 for MRI/DWI, 0.57 for MRI/PET, 0.69 for MRI/DWI/PET and 0.66 for PET/CT. In the organ-based assessment, MRI/DWI/PET showed the highest accuracy for liver metastases (0.74), a comparable accuracy to PET/CT in peritoneal lesions (0.55), and in lymph node metastases (0.84). The accuracy in mucinous tumour lesions was limited in all modalities (MRI/DWI/PET = 0.52). CONCLUSIONS: PET/MRI including DWI is comparable to PET/CT in the evaluation of colorectal cancer metastases, with a markedly higher accuracy when using combined imaging data than the modalities separately. Further improvement is needed in the imaging of peritoneal carcinomatosis and mucinous tumours.

[Primary perivascular epitheloid cell tumour (PEComa) of the liver - is a new entity of the liver tumors?]. / Das PECom der Leber - eine neue Entität der Lebertumoren?

Perivascular epitheloid cell tumor (PEComa) is a rare tumor, characterized by dual Expression of smooth muscle and melanocytic markers. Due to the development of diagnostic procedures, we now diagnose PEComa more often. We report about a case of PEComa of the liver as an accidental finding. We analyze the clinical and morphological characteristics of this tumor and compare it with the data of the literature. Management of patients with PEComa is not yet standardized; therefore biopsy with immunhistochemical staining is necessary for the diagnosis. In case of liver tumors which cannot be classified by their morphology on imaging modalities, it is important to think about this rare entity.

Forms of energy delivery during cryo-cooled radiofrequency ablation for optimization of the ablation result.

PURPOSE: Energy transfer from radiofrequency (RF) applicator to tissue is both precondition and limiting factor. The purpose of this ex vivo study was to examine the influence of form of energy delivery on ablation result during RF ablation with cryo-cooled applicators. MATERIALS AND METHODS: One hundred eight ablations were performed in ex vivo bovine liver under continuous energy delivery (A), pulsed energy delivery with reduced current during ablation pause (B) and impedance-dependent energy delivery. Maximum ablation time was 20 min. Early termination of ablation in case of loss of conductivity. Optimal ablation parameters were assessed. Short axis diameter of the ablation zone and ablation duration were determined. Ablation results under mode A, B and C were compared with analysis of variance and Tukey-Kramer HSD test. Influence of ablation duration on short axis diameter was evaluated with regression analysis. RESULTS: Significantly largest short axis diameter (51.1 mm ± SD 2.3; p = 0.01) was reached with impedance-dependent energy delivery (pulsed: 46.1 mm ± SD 5.6; continuous: 44.4 mm ± SD 4.1). Significantly longest ablation duration (1061.6 s ± SD 42.4; p = 0.01) was reached with impedance-dependent energy delivery (pulsed: 815.7 s ±â€Š41.3; continuous: 715.3 s ± SD 82.2). Linear correlation between ablation duration and short axis diameter was calculated (R = 0.7). CONCLUSION: Modification of energy delivery during RF ablation with cryo-cooled applicators improves energy transfer to tissue and enables larger ablation zones. KEY POINTS: • Impedance-dependent energy delivery prevents early termination in kryo-based RF-ablation,• Impedance-dependent energy delivery enables larger ablation zones than continuous energy delivery,• Reduced current during ablation pause does not improve ablation results.

[Image-guided therapy with closed MRI: an update]. / Image-Guided Therapy am geschlossenen MRT: Ein Update.

STANDARD RADIOLOGICAL METHODS: Standard imaging modalities for percutaneous minimally invasive therapy are ultrasound, fluoroscopy and computed tomography. METHODICAL INNOVATIONS: Magnetic resonance imaging is becoming increasingly more popular for minimally invasive procedures. The advantages are high soft-tissue contrast, the possibility of free selection of multiple imaging slices, multiple tools for intrainterventional monitoring and the absence of ionizing radiation for the patient and the interventional radiologist. ACHIEVEMENTS: Magnetic resonance imaging is a promising imaging modality for minimally invasive procedures. The most common clinical applications are thermoablative procedures for treatment of hepatic, renal and prostatic malignancies.

[Microwave tumor ablation. New devices, new applications?]. / Mikrowellenablation. Neue Systeme, neue Einsatzgebiete?

CLINICAL ISSUE: The majority of patients with hepatic malignancies are not amenable to surgical resection. In some of these cases minimally invasive ablative therapies are a treatment option. STANDARD TREATMENT: Besides radiofrequency ablation, the most common ablative therapies are cryoablation, laser ablation and microwave ablation. TREATMENT INNOVATIONS: The classic fields of application of microwave ablation are the treatment of malignancies of the liver, kidneys and lungs. Furthermore, cases of treatment of bone tumors and tumors of the adrenal gland have been reported as well as treatment of secondary hypersplenism. PERFORMANCE: The manufacturers of microwave systems pursue different strategies to reach an optimal ablation zone, such as water or gas cooling of the antenna, the simultaneous use of different antennas or an automatic modulation of the microwave energy and frequency. ACHIEVEMENTS: In contrast to other tumor ablation methods microwave ablation causes a direct heating of a tissue volume, thus this method is less vulnerable to the cooling effect of vessels in the ablation zone. Moreover the electric conductivity of the treated tissue does not influence microwave radiation so that microwave ablation has advantages for the treatment of high-resistance organs, such as the lungs or bone. Some publications have shown that microwave ablation causes larger ablation zones in less time in comparison to radiofrequency ablation. PRACTICAL RECOMMENDATIONS: Classic indications for microwave ablation are the treatment of malignancies of the liver, lungs and kidneys. Initial technical problems have been solved, so that an increasing significance of the microwave ablation among the ablative therapies is to be expected.

[CT-guided radiofrequency (RF) ablation of osteoid osteoma: clinical long-term results]. / CT-gesteuerte Radiofrequenz (RF)-Ablation von Osteoidosteomen: klinische Langzeitergebnisse.

PURPOSE: To evaluate CT-guided radiofrequency (RF) ablation of osteoid osteoma using internally cooled monopolar RF electrodes for technical success, complications and clinical long-term success. MATERIALS AND METHODS: Between April 1999 and July 2006, 23 patients were treated under general anesthesia with CT-guided RF ablation using an internally cooled monopolar single RF electrode (Cool-tip, Valleylab, TycoHealthcare, Boulder, USA; active tip: 10 mm). For the removal of the nidus, we used either a manual or an automated drill. The technical success was evaluated by a CT scan (MSCT, Siemens Medical Solutions, Forchheim). The clinical long-term success was investigated by questioning patients prior to discharge, and after 6, 12 and 18 months. After 18 months, patients were interviewed on an annual basis. RESULTS: The technical success rate was 100 %. The nidus was located in n = 19 cases at the lower extremity and in n = 4 cases at the upper extremity. Minor complications were observed for n = 2 patients. The mean hospitalization time was 1.5 d (1-2 d). The mean follow-up was 75.9 months (18-120 months) for n = 23 patients. No local recurrence was observed. One patient had intermediate pain one week after RF ablation without recurrent symptoms. CONCLUSION: CT-guided RF ablation using an internally cooled monopolar single RF electrode is an effective and safe minimally invasive method for the treatment of osteoid osteoma with excellent clinical long-term success.

[Metastases of colorectal carcinoma]. / Metastasen des kolorektalen Karzinoms.

Metastases of colorectal cancer represent an interdisciplinary therapeutic challenge. Evidence-based guidelines are supportive of treatment decisions in specific situations with the objective to improve the therapeutic outcome for patients. Interventional tumor therapies are increasingly applied therapeutic options in the treatment of colorectal metastases. The current literature indicates that thermoablation of colorectal liver metastasis can lead to an improved survival in selected patients. However, recommendation of thermoablation as a part of guidelines for the therapy of colorectal metastases is restricted due to a shortcoming of randomized controlled trials. Therefore, interventional tumor therapies have to be evaluated in comparison with standard therapies, particularly with regard to surgical resection and chemotherapy. Moreover, the interdisciplinary combination of tumor ablation, surgical resection, and chemotherapy is a promising approach for the optimization of oncological therapy strategies in the treatment of colorectal metastases.

Human endothelial cell septins: SEPT11 is an interaction partner of SEPT5.

The septin SEPT11 is a novel member of the highly conserved septin family. Septins are cytoskeletal GTPases, which form heteropolymeric complexes. They are involved in cytokinesis and other cellular processes, such as vesicle trafficking and exocytosis. SEPT11 has strong homology to SEPT8. Previously, we identified the interaction of SEPT5 and SEPT8. Using the yeast two-hybrid system, we now demonstrate that SEPT11 partners with SEPT5. The molecular interaction of SEPT11 with SEPT5 was verified by coprecipitation of SEPT5 and SEPT11 from lysates of the human T-cell leukaemia cell line JURKAT and by fluorescence resonance energy transfer. The interaction between SEPT5 and SEPT11 requires the GTP-binding domain and the C-terminal extension. Western analysis in various mouse and human tissues revealed that expression of SEPT11 is restricted to the same tissues as those expressing SEPT5, suggesting that SEPT11 and SEPT5 are components of a cell-specific septin complex. SEPT5, which is expressed in human umbilical vein endothelial cells (HUVECs), has been reported to play an important role in exocytosis. We now report that HUVECs also express SEPT11. Given the interactivity between SEPT5 and SEPT11 as shown above and their coexpression in HUVECs, it may be that a complex formed by these two proteins is involved in the exocytosis mechanism in HUVECs.