Perivascular vital cells in the ablation center after multibipolar radiofrequency ablation in an in vivo porcine model

Multibipolar radiofrequency ablation (RFA) is an advanced ablation technique for early stage hepatocellular carcinoma and liver metastases. Vessel cooling in multibipolar RFA has not been systematically investigated. The objective of this study was to evaluate the presence of perivascular vital cells within the ablation zone after multibipolar RFA. Multibipolar RFA were performed in domestic pigs in vivo. Three internally cooled bipolar RFA applicators were used simultaneously. Three experimental settings were planned: (1) inter-applicator-distance: 15 mm; (2) inter-applicator-distance: 20 mm; (3) inter-applicator-distance: 20 mm with hepatic inflow occlusion (Pringle maneuver). A vitality staining was used to analyze liver cell vitality around all vessels in the ablation center with a diameter > 0.5 mm histologically. 771 vessels were identified. No vital tissue was seen around 423 out of 429 vessels (98.6%) situated within the central white zone. Vital cells could be observed around major hepatic vessels situated adjacent to the ablation center. Vessel diameter (> 3.0 mm; p < 0.05) and low vessel-to-ablation-center distance (< 0.2 mm; p < 0.05) were identified as risk factors for incomplete ablation adjacent to hepatic vessels. The vast majority of vessels, which were localized in the clinically relevant white zone, showed no vital perivascular cells, regardless of vessel diameter and vessel type. However, there was a risk of incomplete ablation around major hepatic vessels situated directly within the ablation center. A Pringle maneuver could avoid incomplete ablations.

[Acute vestibular syndrome in emergency departments : Clinical differentiation of peripheral and central vestibulopathy]

INTRODUCTION

The differentiation between central and peripheral vestibular disorders is difficult in some cases, especially during the clinical routine of an emergency department (ED) without otoneurological diagnostic equipment. This study evaluated the frequency of vestibular pseudoneuritis as distinguished from acute peripheral vestibular disorders in patients who were admitted to hospital with the suspicion of vestibular neuropathy (VN).

METHODS

This retrospective study analyzed the results of anamnestic and clinical examinations of 315 patients admitted to the emergency department and the inpatient otoneurological examination results as well as the imaging of morphological alterations. In the ED, the clinical examination by a neurologist and an otorhinolaryngologist resulted in the characteristic signs of peripheral VN but no further evidence of a neurological disorder. Patients without signs of a peripheral vestibular disorder in the otoneurological diagnostics subsequently underwent cerebral magnetic resonance imaging scans (cMRI).

RESULTS

Suspected isolated VN could be confirmed in 69% of the patients; however, in a further 29% of the patients neither the suspected isolated VN nor an ischemic pathology of the central nervous system as a cause of the vertigo could be confirmed. Additional cMRI scans revealed that 2% of patients suffered from an infarction of the mesencephalon, the pons, the medulla oblongata and the cerebellum.

CONCLUSION

In rare cases central cerebral disorders mimic the pattern of a peripheral vestibular disorder. Despite thorough history taking, neurological and otolaryngological clinical examinations, it is not always possible to distinguish central and peripheral vestibular disorders of patients in emergency care suffering from acute vertigo. Video oculography-assisted caloric testing and the video head impulse test are recommended to confirm a peripheral VN. In cases without confirmation of suspected NV in otoneurological diagnostics, infarction of the mesencephalon, brain stem and cerebellum should be excluded by diffusion-weighted cMRI.

Inter- and Intrareader Agreement of NI-RADS in the Interpretation of Surveillance Contrast-Enhanced CT after Treatment of Oral Cavity and Oropharyngeal Squamous Cell Carcinoma

BACKGROUND AND PURPOSE

The Neck Imaging Reporting and Data System was introduced to assess the probability of recurrence in surveillance imaging after treatment of head and neck cancer. This study investigated inter- and intrareader agreement in interpreting contrast-enhanced CT after treatment of oral cavity and oropharyngeal squamous cell carcinoma.

MATERIALS AND METHODS

This retrospective study analyzed CT datasets of 101 patients. Four radiologists provided the Neck Imaging Reporting and Data System reports for the primary site and neck (cervical lymph nodes). The Kendall's coefficient of concordance (W), Fleiss κ (κ_F), the Kendall's rank correlation coefficient (τ_B), and weighted κ statistics (κ_w) were calculated to assess inter- and intrareader agreement.

RESULTS

Overall, interreader agreement was strong or moderate for both the primary site (W = 0.74, κ_F = 0.48) and the neck (W = 0.80, κ_F = 0.50), depending on the statistics applied. Interreader agreement was higher in patients with proved recurrence at the primary site (W = 0.96 versus 0.56, κ_F = 0.65 versus 0.30) or in the neck (W = 0.78 versus 0.56, κ_F = 0.41 versus 0.29). Intrareader agreement was moderate to strong or almost perfect at the primary site (range τ_B = 0.67-0.82, κ_w = 0.85-0.96) and strong or almost perfect in the neck (range τ_B = 0.76-0.86, κ_w = 0.89-0.95).

CONCLUSIONS

The Neck Imaging Reporting and Data System used for surveillance contrast-enhanced CT after treatment of oral cavity and oropharyngeal squamous cell carcinoma provides acceptable score reproducibility with limitations in patients with posttherapeutic changes but no cancer recurrence.

[Space-occupying lesion in the maxillary sinus]

During the preoperative diagnostics of an 80-year-old male patient prior to a planned endarterectomy, an unclear space-occupying lesion was detected in the right nasopharyngeal cavity. It proved to be a dense soft tissue space-occupying lesion of the right maxillary sinus. The histological investigations revealed a partially necrotically decomposed malignant tumor below normal respiratory mucosa free from dysplasia. This case demonstrates the difficulties in differential diagnostics, particularly involving (aberrant) expression of cytokeratin.

Influence of pelvic volume on surgical outcome after low anterior resection for rectal cancer

BACKGROUND

Low anterior resection (LAR) for rectal cancer is a potentially challenging operation due to limited space in the pelvis. CT pelvimetry allows to quantify pelvic space, so that its relationship with outcome after LAR may be assessed. Studies investigating this, however, yielded conflicting results. We hypothesized that a small pelvis is associated with a higher rate of incomplete mesorectal excision, anastomotic leakages, and increased rate of urinary dysfunction in patients operated for rectal cancer.

METHODS

In a single-center retrospective analysis, we studied 74 patients that underwent LAR for rectal cancer with primary anastomosis. Thin-layered multi-slice CT datasets were used for slice by slice depiction of the inner pelvic surface, and the inner pelvic volume was automatically compounded. The primary outcome was quality of total mesorectal excision (TME; Mercury grading); secondary outcomes were anastomotic leakage and urinary dysfunction with regard to pelvic dimensions. Univariate analyses and multiple logistic regression analyses were performed for the primary and the secondary outcomes.

RESULTS

Shorter obstetric conjugate diameters were associated with a higher probability of a worse TME quality (110.8 ± 10.2 vs. 105.0 ± 8.6 mm; OR 0.85; 95% CI 0.73-0.99; p = 0.038). Short interspinous distance showed a trend towards an increased risk for deteriorated TME quality (OR 0.88; 95% CI 0.76-1.0; p = 0.06). Anastomotic leakage was associated with anemia (OR 2.77; 95% CI 1.0-7.7; p = 0.047). Association between pelvic diameters or pelvic volume and anastomotic leakage or urinary dysfunction was not observed. Perioperative blood transfusions were administered more often in patients with postoperative urinary dysfunction (OR 17.67; 95% CI 2.44-127.7; p = 0.004).

CONCLUSION

Shorter obstetric conjugate diameter might be a risk factor for incompleteness of total mesorectal excision. Anastomotic leakage seems to be influenced more by clinical factors such as anemia rather than pelvic dimensions. Further studies have to prove the influence of pelvic diameter on local recurrence of rectal cancer after LAR.

Tissue reaction induced by implanted venous access ports in adult patients after infection of the implantation site

Implantable long-term central venous port systems (CVPS) are widely used as a permanent means of accessing the vascular system for intravenous delivery of drugs, parenteral nutrition, blood transfusion, and blood sampling. These systems allow easy and repetitive puncture without causing much damage to the vessels. However, the body foreign surface of CVPS induces an inflammatory response with varying intensity (depending on the implant materials) that leads to formation of a fibrous tissue capsule around the implant. This study was designed to investigate the influence of bacterial infection on the tissue reaction induced by implanted CVPS in adult patients. 20 patients (9 women, 11 men, 58 ± 14 yrs of age) were included in this study. These patients received explantation of a polysulfone based CVPS (ChemoSite™, Covidien, Mansfield, USA) due to port related infections (patients with bacterial infections at the implantation site: group A, 5 men, 1 women) or to other reasons such as termination of treatment, thrombosis, or CVPS dysfunction (patients without bacterial infections, group B, 6 men, 8 women) 299.9 ± 261.2 days after CVPS implantation. A sample of the encapsulating tissue covering the CVPS together with surrounding tissue (at least 1 × 1 cm2) was placed in a small container with fixing agent, a buffered neutral 4% formalin solution (pH 7). Histological sections of the samples were prepared for light microscopic analysis after paraffin embedding. Sections of 3 μm were cut and stained with haematoxylin and eosin, Weigert's elastic stain, and Heidenhain's azan stain. There was no difference in thickness, collagen and elastin content, or cell and capillary density of the fibrous capsule between both groups. Due to the wound healing reaction involving angiogenesis and fibroblast activation cell density and number of capillaries in the capsule tissue of all patients showed a positive correlation (r = 0.45, p < 0.05). However, the study demonstrated that at the end of the foreign body reaction the artificial tissue layer which covers the CVPS after implantation due to foreign body reaction shows only low reactivity towards infections.

The effect of prone versus supine positioning of Goettingen minipigs on lung density as viewed by computed tomography

Minipigs are frequently used for scientific research as they are easy to handle and the dimensions of their vascular system do not change after 20 months of age. Although surgical interventions under anaesthesia are often performed in the supine position the effects of this positioning on lung functionality in minipigs have not been systematically described. This study aimed to analyse the influence of supine positioning on the macrostructure of the lung and the pulmonary density by the use of computed tomography imaging in pre-adult Göttingen minipigs. Twelve pre-adult female minipigs were used in the study and lung density was investigated in both the prone and the supine positions. The time between the scans in prone and supine positions was less than 5 minutes (296 ± 6 sec). In the prone position lung density did not differ between the dorsal and ventral part of the lung (-641 ± 72 Hounsfield units [HU]). However in the supine position there was a ventrodorsal gradient of decreasing density (ventral part of the lung: -497 ± 106 HU, dorsal part of the lung: -723 ± 51 HU). The changes in lung density were not accompanied by changes in lung volume (829 ± 191 ml). These results suggest an influence of the body position on the ventilation/perfusion (V(A)/Q) matching of the lung which could possibly result in lowered lung oxygenation as well as in an increased heart activity in the supine position. Additionally, due to the steep course of the vena cava caudalis from the caval foramen in the diaphragm across to the heart (in contrast to the more shallow course in the prone position) the activity of the heart necessary to pump the venous blood to the right atrium has to be higher in the supine position than in the prone position. In pigs the capacity of the heart to increase frequency is limited due to a diastolic/systolic (D/S) ratio <1. Supine positioning may possibly increase their risk of cardiovascular complications.

A NiTi alloy-based cuff for external banding valvuloplasty: a six-week follow-up study in pigs

OBJECTIVE

The study aimed to test a Nitinol(®)-based vein cuff model for external banding valvuloplasty.

METHOD

In 12 adult minipigs, the vena jugularis externa was covered for 42 days by a cuff with an inner diameter adapted to the outer vein diameter in supine position. By changing from supine into prone position hypostatically vein dilation was induced to simulate varicose vein dilation. Cuff position and the inner diameter of the vein lumen under the cuff were examined by computer tomography scanning. Also, histological analysis of the vein wall within the cuff was performed.

RESULTS

The preset tubular shape of the cuff and the cuff position did not change in both prone and supine position, but due to fibrosis the luminal vein diameter within the cuff was decreased (P < 0.01) already after 21 days.

CONCLUSION

A foreign body response resulted in a fibrous capsule covering the cuff which might limit cuff functionality.

Ventral recumbency is crucial for fast and safe orotracheal intubation in laboratory swine

The aim of this study was to find the fastest, easiest and safest method of achieving orotracheal intubation for general anaesthesia in laboratory pigs. Twenty-one Yorkshire × Landrace crossbreed male castrated pigs (32.9 ± 4.8 kg) were investigated. Dorsal and ventral recumbency are the alternatives most frequently described for animal positioning during intubation procedures. Based on standardized induction of general anaesthesia using pentobarbital and remifentanil, the dorsoventral and ventrodorsal positions were compared with regard to the time needed, changes in oxygenation and circulatory response. Positioning was found to be crucial for fast orotracheal intubation. The time required for safe intubation is significantly shorter with the ventrodorsal position (17.3 s) in comparison with the dorsoventral position (58.4 s; P < 0.001). Hypoxia did not occur in either group. A significant drop in systolic blood pressure was observed in both groups. Diastolic and mean arterial pressures were not influenced by intubation. A significant increase in heart rate was observed in pigs intubated in ventral recumbency, but not after intubation in the dorsal position. Preoxygenation before intubation is vitally important for preventing hypoxia. With regard to clinical practice, the haemodynamic changes observed in this investigation do not appear to be relevant, as the mean arterial pressure was not altered and heart rates only increased moderately. It may be concluded that the ventrodorsal position can be recommended for orotracheal intubation in pigs as the first choice for providing a smooth and fast airway.

[Ultrasound contrast agents for liver diagnostics]

Ultrasound contrast agents have achieved a high level of acceptance in diagnostics of liver tumors. Contrast-enhanced ultrasound can, on the one hand, be used for detection of liver tumors, e.g., during the search for metastases in tumor staging, and, on the other hand, for tumor characterization. The dispersion behavior of the ultrasound contrast agent plays a decisive role in the characterization and the enhancement patterns correspond to a large extent to those already known from contrast-enhanced computed tomography. Contrast-enhanced ultrasound can also be employed for monitoring ablative tumor therapies, visualization of vessels difficult to depict, and measurement of the so-called liver transit time.

[Digital knowledge in the coat pocket -- hand-held personal digital assistants in radiology]

The personal digital assistant (PDA) enables the independent access to large data in a pocket-sized format. The applications for hand-held computers are growing steadily and can support almost any kind of problem. An overview of the available hardware and software is provided and evaluated. Furthermore, the use of the PDA in the clinical daily routine is described. In view of the numerous software programs available in radiology, the range of software solutions for radiologists is presented. Despite the high acquisition cost, the PDA has already become the digital assistant for the radiologist. After a short time of getting used to the PDA, nobody wants to miss it at work or at home. New technical features and available software programs will continuously increase the integration of the PDA into the medical workflow in the near future.

Klinischer Einsatz der digitalen retrospektiven Bildfusion von CT, MRT, FDG-PET und SPECT - Anwendungsgebiete und Ergebnisse

PURPOSE

To evaluate the feasibility and the clinical benefits of retrospective digital image fusion (PET, SPECT, CT and MRI).

MATERIALS AND METHODS

In a prospective study, a total of 273 image fusions were performed and evaluated. The underlying image acquisitions (CT, MRI, SPECT and PET) were performed in a way appropriate for the respective clinical question and anatomical region. Image fusion was executed with a software program developed during this study. The results of the image fusion procedure were evaluated in terms of technical feasibility, clinical objective, and therapeutic impact.

RESULTS

The most frequent combinations of modalities were CT/PET (n = 156) and MRI/PET (n = 59), followed by MRI/SPECT (n = 28), CT/SPECT (n = 22) and CT/MRI (n = 8). The clinical questions included following regions (more than one region per case possible): neurocranium (n = 42), neck (n = 13), lung and mediastinum (n = 24), abdomen (n = 181), and pelvis (n = 65). In 92.6 % of all cases (n = 253), image fusion was technically successful. Image fusion was able to improve sensitivity and specificity of the single modality, or to add important diagnostic information. Image fusion was problematic in cases of different body positions between the two imaging modalities or different positions of mobile organs. In 37.9 % of the cases, image fusion added clinically relevant information compared to the single modality.

CONCLUSION

For clinical questions concerning liver, pancreas, rectum, neck, or neurocranium, image fusion is a reliable method suitable for routine clinical application. Organ motion still limits its feasibility and routine use in other areas (e. g., thorax).

[Virtual MR endoscopy of the ventricles prior to neurosurgical interventional endoscopy -- evaluation of different presentation techniques]

PURPOSE

In the past, virtual endoscopies have been performed for planning of endoscopic interventions or for diagnostic purposes in various organ systems with increasing frequency. This study evaluates the ability of virtual ventricular endoscopy to depict anatomical structures and the use for planning of real endoscopy.

MATERIALS AND METHODS

In a prospective study, 4 volunteers and 8 patients were examined with MRI. In 3 of the patients endoscopy was performed by our neurosurgeons thereafter. The calculation of the virtual endoscopy was based on 1 mm sagittal T2-weighted images. Comparison of surface rendering and volume rendering was made by means of video sequencing of individual views, and these were compared with the intraoperative endoscopic videos concerning the depictability of anatomical landmarks.

RESULTS

The reconstructions using volume rendering were more significant and easier to calculate than those based on surface rendering. Virtual endoscopy in the transparent mode allowed visualization of hazardous structures outside the ventricular system such as the basilar artery tip. Transparent 3D images of the ventricles gave a good overview on the depicted structures and enabled a better orientation during the virtual camera flight than surface rendered views.

CONCLUSION

MR-based virtual endoscopy of the ventricular system can be obtained on the basis of surface- and volume-rendered views of sagittal T2-weighted thin sections. Preoperative utilization of this method simplifies the planning of endoscopy by visualization of anatomical structures.