Preclinical Assessment of Tissue Effects by Gastrointestinal Endoscope Tip Temperature

Background

Endoscope tips are heated by their electrical and illuminating components. During the procedure, they might get in close or even direct contact with intestinal tissues.

Objective

To assess endoscope tip and tissue temperature as well as histopathologic changes of gastrointestinal (GI) tissues when exposed to the heated tip of GI endoscopes.

Methods

The endoscope tip temperatures of four GI endoscopes were measured for 30 minutes in a temperature-controlled chamber. The temperature of ex vivo porcine GI tissues was measured for 5-, 15-, and 120-minute exposure to endoscope tips within a climate chamber to control environmental factors (simulation of fever as worst-case). Exposed tissues were histopathologically examined afterward. Control samples included untreated mucosa, tissue samples exposed to endoscope tips for 120 minutes, as well as tissue samples thermally coagulated with a bipolar high-frequency probe.

Results

Actual endoscope tip temperatures of 59 to 86°C, dependent on the endoscope type, were measured. After 10 to 15 minutes, the maximum temperatures were reached. Maximum tissue temperatures of 44 to 46°C for 5 and 15 minutes, as well as up to 50°C for 120 minutes, were recorded dependent on tissue and endoscope type. No direct heat-induced histopathologic tissue alterations were observed in the 5- and 15-minute samples.

Conclusions

Both clinically relevant and a worst-case control were tested. Even though elevated temperatures were recorded, no heat-related tissue alterations were detected. This overall supports the safety profile of GI endoscopy; however, the study findings are limited by the ex vivo setting (no metabolic tissue alterations accessible, no blood flow) and small sample number.

18F-labeling and initial in vivo evaluation of a Hitomi peptide for imaging tissue transglutaminase 2

INTRODUCTION

Tissue transglutaminase 2 (TG2) is a calcium-dependent enzyme which cross-links proteins. It is overexpressed in many diseases and plays a key role in tissue remodeling, including cell adhesion and migration. Overexpression of TG2 in breast cancer is a marker for patients at risk of recurrence. Non-invasive imaging of TG2 can therefore play an important role in patient management. TG2 probes labeled with the positron emitters ¹¹C and ¹⁸F have thus far not found widespread application due to purity and metabolism issues. Our approach was to radiolabel a TG2 selective, 13-mer amino acid peptide, which was modified with a 5-azidopentanoic acid group at the N-terminus via a copper free click chemistry approach.

METHODS

Radiochemistry was performed and fully automated using an iPhase FlexLab module. We produced the radiolabeling synthon [¹⁸F]FBz-DBCO from [¹⁸F]SFB and DBCO-amine. After HPLC purification, [¹⁸F]FBz-DBCO was reacted with the modified peptide and the putative radiotracer purified by HPLC. In vivo imaging using the radiolabeled amine was performed in mice bearing either TG2 expressing MDA-MB-231 or non-TG2 expressing MCF-7 xenografts as negative control. Expression of the target was confirmed using immunohistochemistry and western blot techniques.

RESULTS

We obtained 9 ± 2 GBq of the radiolabeled peptide from 55 ± 5 GBq of fluorine-18 in an overall synthesis time of 160 min from end of bombardment (EOB), including HPLC purification and reformulation. Small animal PET/MR imaging showed that visualization of MDA-MB-231 tumors using the radiolabeled peptide could only be achieved due to differences in clearance between tumor and surrounding tissue. In the MCF-7 xenograft model, radiotracer clearance from tumor and surrounding tissue occurred at a similar rate, thus making it impossible to visualize MCF-7 tumors. The presence of TG2 in MDA-MB-231 tumors and absence in MCF-7 tumors was confirmed by immunohistochemistry staining and western blot analysis.

CONCLUSION

A fully automated synthesis of a TG2 selective, 13-amino-acid peptide modified with 5-azido pentynoic acid at the N-terminal was established using [¹⁸F]FBzDBCO as a prosthetic group. Although our results show that radiolabeled peptides have potential as imaging agents for TG2, more research needs to be performed to improve radiotracer kinetics.

Rapid and precise delivery of cells in the urethral sphincter complex by a novel needle-free waterjet technology

OBJECTIVES

To investigate the therapy of stress urinary incontinence in a preclinical setting cells were injected into the urethrae of minipigs; however, cells injected by William's needle were frequently misplaced or lost; thus, we investigated if needle-free cell injections using a novel waterjet technology facilitates precise injections in the urethral sphincter complex.

MATERIALS AND METHODS

Porcine adipose tissue-derived stromal cells (pADSCs) were isolated from boars, expanded, labelled, and injected in the sphincter of female pigs by waterjet employing two different protocols. After incubation for 15 min or 3 days, the urethrae of the pigs were examined. Injected cells were visualised by imaging and fluorescence microscopy of tissue sections. DNA of injected male cells was verified by polymerase chain reaction (PCR) of the sex-determining region (SRY) gene. Cell injections by William's needle served as controls.

RESULTS

The new waterjet technology delivered pADSCs faster and with better on-site precision than the needle injections. Bleeding during or after waterjet injection or other adverse effects, such as swelling or urinary retention, were not observed. Morphologically intact pADSCs were detected in the urethrae of all pigs treated by waterjet. SRY-PCR of chromosomal DNA and detection of recombinant green fluorescent protein verified the injection of viable cells. In contrast, three of four pigs injected by William's needle displayed no or misplaced cells.

CONCLUSION

Transurethral injection of viable pADSCs by waterjet is a simple, fast, precise, and yet gentle new technology. This is the first proof-of-principle concept study providing evidence that a waterjet injects intact cells exactly in the tissue targeted in a preclinical in vivo situation. To further explore the clinical potential of the waterjet technology longer follow-up, as well as incontinence models have to be studied.

Hydrojet-based delivery of footprint-free iPSC-derived cardiomyocytes into porcine myocardium

The reprogramming of patient´s somatic cells into induced pluripotent stem cells (iPSCs) and the consecutive differentiation into cardiomyocytes enables new options for the treatment of infarcted myocardium. In this study, the applicability of a hydrojet-based method to deliver footprint-free iPSC-derived cardiomyocytes into the myocardium was analyzed. A new hydrojet system enabling a rapid and accurate change between high tissue penetration pressures and low cell injection pressures was developed. Iron oxide-coated microparticles were ex vivo injected into porcine hearts to establish the application parameters and the distribution was analyzed using magnetic resonance imaging. The influence of different hydrojet pressure settings on the viability of cardiomyocytes was analyzed. Subsequently, cardiomyocytes were delivered into the porcine myocardium and analyzed by an in vivo imaging system. The delivery of microparticles or cardiomyocytes into porcine myocardium resulted in a widespread three-dimensional distribution. In vitro, 7 days post-injection, only cardiomyocytes applied with a hydrojet pressure setting of E20 (79.57 ± 1.44%) showed a significantly reduced cell viability in comparison to the cells applied with 27G needle (98.35 ± 5.15%). Furthermore, significantly less undesired distribution of the cells via blood vessels was detected compared to 27G needle injection. This study demonstrated the applicability of the hydrojet-based method for the intramyocardial delivery of iPSC-derived cardiomyocytes. The efficient delivery of cardiomyocytes into infarcted myocardium could significantly improve the regeneration.

A novel waterjet technology for transurethral cystoscopic injection of viable cells in the urethral sphincter complex

AIMS

In a recent preclinical study, we noticed that injection of cells in the urethral sphincter by needle through a cystoscope under visual control frequently yielded in misplacement or loss of cells. We, therefore, investigated if a needle-free waterjet device delivers viable cells under defined settings, including injection volume and pressure, fluid velocity and transportation media, precisely through the urothelium and connective tissue close to the sphincter muscle without full penetration of the sphincter apparatus.

METHODS

Mesenchymal stromal cells (MSCs) were prepared for needle-free waterjet injections. Upon injections into liquids cell viability and yield were investigated by trypan blue dye exclusion. Upon injection into cadaveric urethral tissue samples, cells were isolated from the urethrae and expanded to prove that this novel method delivered viable cells into the tissue. MSC injections by William's needle served as controls.

RESULTS

Waterjet injections of MSCs into isotonic cell culture medium resulted in equal or better yields of viable cells when compared with needle injections. Upon injection in urethral tissue samples, the waterjet technology facilitated fast and precise injections of viable cells through urothelial, mucosal and submucosal layers to reach the sphincter muscle. By controlling the injection pressure, loss of cells due to insufficient thrust or unintended full penetration was avoided.

CONCLUSIONS

Needle-free waterjet injections deliver cells in the urethra faster and more precisely when compared with needle injections without compromising their viability. This is the first proof-of-concept study providing evidence that a waterjet transports viable cells precisely into the targeted tissue.

Cryobiopsy in the Upper Urinary Tract: Preclinical Evaluation of a Novel Device

OBJECTIVE

To develop a novel device for cryobiopsy of the upper urinary tract (UUT) and to evaluate its feasibility in a standardized preclinical setting.

MATERIALS AND METHODS

Flexible cryoprobes (diameter 0.9 mm; cooling agent CO2) were developed and used to extract biopsies in porcine UUTs. Cryosamples obtained by ureterorenoscopy were systematically compared with biopsy specimens obtained with standard of care devices in terms of physical characteristics (deflection angle and irrigation flow rates) and histologic criteria (assessability).

RESULTS

Irrigation flow rates were significantly higher with introduced BIGopsy (2.8 ± 0.1) compared with standard forceps (0.94 ± 0.06; P < .001) and cryoprobe (1.1 ± 0.1; P < .001). Angular deflection was significantly reduced by the inserted cryoprobe (130.7° ± 1.2° vs 166.9° ± 1.1° [BIGopsy] or 161.4° ± 1.9° [standard forceps]; both P < .001). Significantly larger UUT tissue samples were obtained by the cryoprobe (mean specimen area 7.5 ± 2.5 vs 4.6 ± 2.5 mm² [BIGopsy] or 1.4 ± 1.4 mm² [standard forceps]; both P < .001). No crush artifacts were observed in cryosamples. Superior histologic assessability scores were achieved in samples obtained by the cryoprobe (mean 2.8 ± 0.8) and BIGopsy (2.3 ± 1.9) when compared with standard forceps (0.4 ± 0.9; P < .001).

CONCLUSION

Cryobiopsy in the UUT is feasible and represents a viable new option to improve the diagnostic accuracy of histopathologic evaluation. Larger and more representative tissue samples can be obtained using a cryoprobe and artifacts may be avoided. Further optimization of the probe will reduce possible restrictions of ureterorenoscopy handling when the device is inserted.

Age effects on the P300 potential and the corresponding fMRI BOLD-signal

Age has been reported to influence amplitude and latency of the P300 potential. Nevertheless, it is not yet fully understood which brain regions are responsible for these effects. The aim of this study was to investigate age-effects on the P300 potential and the simultaneously acquired BOLD signal of functional MRI. 32 healthy male subjects were investigated using an auditory oddball paradigm. The functional MRI data were acquired in temporal synchrony to the task. The evoked potential data were recorded during the intervals in between MR image acquisitions in order to reduce the influence of the scanner noise on the presentation of the tones and to reduce gradient artifacts. The age-effects were calculated by means of regression analyses. In addition, brain regions modulated by the task-induced amplitude variation of the P300 were identified (single trial analysis). The results indicated an age effect on the P300 amplitude. Younger subjects demonstrated increased parietal P300 amplitudes and increased BOLD responses in a network of brain regions including the anterior and posterior cingulate cortex, the insula, the temporo-parietal junction, the superior temporal gyrus, the caudate body, the amygdala and the parahippocampal gyrus. Single trial coupling of EEG and fMRI indicated that P300 amplitudes were predominantly associated with neural responses in the anterior cingulate cortex, the putamen and temporal brain areas. Taken together, the results indicate diminished neural responses in older compared to younger subjects especially in frontal, temporo-parietal and subcortical brain regions.

[Spontaneous retropharyngeal hematoma: a rare differential diagnosis of acute dysphagia]

Spontaneous retropharyngeal hematoma is a rare but potentially fatal disease. It occurs with no underlying medical condition such as trauma, hemorrhagic diathesis, or medically induced anticoagulation.We report a case of a 48-year-old man who presented with progressive dysphagia, signs of inflammation, and a reduced general health status. There was distinct hemorrhagic swelling of the posterior and lateral walls of the nasopharynx, oropharynx, and hypopharynx, as well as red discoloration of the neck. No underlying medical conditions, medications, or trauma were reported.In light of the current case and the available literature, we present the necessary diagnostic procedures and treatment options. Because the course of this disease might be fatal due to rapid airway obstruction and progressive internal blood loss, it is of utmost importance to keep this diagnosis in mind for differential diagnostic considerations.

[Isolated apical petrositis: an atypical case of Gradenigo's syndrome]

In 1904 Guiseppe Gradenigo described an infection of the apex of the petrous part of the temporal bone from acute otitis media with the clinical symptoms of unilateral pain around the eye, diplopia due to sixth nerve paralysis and persistant otorrhea. While this infection became evident by inward extension from petrositis in the majority of fatal cases from acute otitis media in the preantibiotic era, it has now become very rare. Today, cases mainly derive from cholesteatomas or chronic osteomyelitis of the petrous bone. However, due to intense antibiotic treatment in acute otitis media clinical signs of petrositis may be less typical compared to former times. We report on a 12-year-old boy with rapid onset of sixth nerve paralysis without clinical signs of acute otitis media or mastoiditis. CT and NMR imaging confirmed infection of the petrous apex. He was treated by mastoidectomy with exploration of a posterior cell group from the epitympanon around the semicircular canals and subsequent high dose intravenous antibiotics. The patient recovered without any loss of inner ear or facial nerve function. The paralysis of the sixth nerve disappeared completely within 6 weeks.

Entzündungen des Hirnstamms und des Kleinhirnbrückenwinkels

Inflammatory lesions of the brainstem and the cerebellopontine angle are often critical for the patient, because crucial neuronal and vascular structures are found in this region. The patient's prognosis mainly depends on rapid identification of the inflammation site and the radiological evaluation of the inflammation pathogenesis to develop therapeutic strategies. Therefore, cross-sectional imaging is complementary to laboratory and CSF analysis as well as biopsies. This article gives a survey of inflammatory lesions of the brainstem and the cerebellopontine angle.

Analysis and Correction of Ballistocardiogram Contamination of EEG Recordings in MR

PURPOSE

To examine the influence of cardiac activity-related head movements and varying blood pulse frequencies on the shape of electroencephalography (EEG) recordings in a high magnetic field, and to implement a post-processing technique to eliminate cardiac activity-related artifacts.

MATERIAL AND METHODS

Respiratory thoracic movements, changes of blood pulse frequency and passive head movements of 20 healthy subjects were examined outside and inside an MR magnet at rest in a simultaneously recorded 21-channel surface EEG. An electrocardiogram (ECG) was recorded simultaneously. On the basis of the correlation of the left ventricular ejection time (LVET) with the heart-rate, a post-processing heart-rate dependent subtraction of the cardiac activity-related artifacts of the EEG was developed. The quality of the post-processed EEG was tested by detecting alpha-activity in the pre- and post-processed EEGs.

RESULTS

Inside the magnet, passive head motion but not respiratory thoracic movements resulted in EEG artifacts that correlated strongly with cardiac activity-related artifacts of the EEG. The blood pulse frequency influenced the appearance of the cardiac activity-related artifacts of the EEG. The removal of the cardiac activity-related artifacts of the EEG by the implemented post-processing algorithm resulted in an EEG of diagnostic quality with detected alpha-activity.

CONCLUSION

When recording an EEG in MR environment, heart rate-dependent subtraction of EEG artifacts caused by ballistocardiogram contamination is essential to obtain EEG recordings of diagnostic quality and reliability.

Niikawa-Kuroki-Syndrom

Niikawa-Kuroki syndrome (Kabuki make-up syndrome) is a congenital disorder with characteristic facial features and possibly anomalies of the skeletal system and internal organs. There is an increasing number of reports of patients with combined hearing impairment, inner ear deformities or sensorineural hearing impairment. In addition, the patients often suffer from therapy-resistant chronic otitis media. In addition to multiple cardiac and renal deformities, our 3 year old patient has a hearing impairment due to chronic otitis media with chronic otorrhea, and requires a hearing aid. A high-definition CT scan of the petrosal bone revealed, for the first time in a patient with Niikawa-Kuroki syndrome, a large vestibular aqueduct syndrome and deformities of the vestibular system. We examine the problems involved with treating chronic otorrhea in chronic otitis media and providing patients with BTE hearing aids.

Vertical oscillopsia in bilateral superior canal dehiscence syndrome

A patient sought treatment for vertical oscillopsia and impaired vision during locomotion, and unsteadiness of gait. Positive fistula tests and CT of the temporal bones confirmed a diagnosis of bilateral superior canal dehiscence. An impairment of the superior canal vestibulo-ocular reflex, documented by three-dimensional search coil eye movement recordings for oblique (single) and downward pitch head motion (bilateral canal testing), is proposed to induce vertical rather than torsional-vertical oscillopsia during locomotion.

Simultaneous ERP and event-related fMRI: focus on the time course of brain activity in target detection

The event-related P300 potential has been widely used in neurophysiological research. It is usually evoked with an oddball paradigm. One main reason for its broad application in neurophysiological research is the fact that in several brain/mental diseases, such as Alzheimer's disease or schizophrenia, attenuations of the P300 amplitude and latency have been described. However, a precise correlation of the scalp data to the underlying brain regions was not possible, as the correct localization of the generators of scalp-measured electroencephalogram (EEG) data was limited, due to the low spatial resolution of EEG-data. With the availability of modern imaging technologies, functional Magnetic Resonance Imaging (fMRI) in particular, the underlying brain activations could be detected using an oddball task. Although the spatial resolution of fMRI is excellent, the time resolution is restricted. For a comprehensive understanding of the brain activity underlying the P300 paradigm, we have used a combination of EEG and fMRI to get a precise localization and a high-time resolution of the underlying brain activity.

[Correlation of FDG-PET and MRI/CT with histopathology in primary diagnosis, lymph node staging and diagnosis of recurrency of head and neck cancer]

AIM

Correct staging of head and neck cancer is important for the patient's prognosis and further therapeutic strategies. Aim of the present study was to investigate the diagnostic value of FDG-PET regarding the pre-surgical diagnosis of primary tumor and cervical lymph node metastases, the diagnosis of tumour recurrence, and the localisation of unknown primary, further to compare the results to those of morphological imaging modalities (CT/MRI) and to correlate the results of both methods with histopathological findings.

PATIENTS/METHODS

115 patients (pts) (72 x primary diagnosis, 37 x recurrence, and 6 x unknown primary) underwent FDG-PET (ECAT EXACT HR+) and CT or MRI. Results were correlated with histopathological findings in terms of detection of primary and recurrent tumors as well as lymph node metastases.

RESULTS

Regarding the pre-surgical diagnosis, sensitivity and specificity for identifying primary tumors were 85 % and 100 % for PET and 88 % and 75 % for CT/MRI, respectively. Accuracy was 86 % for PET and 87 % for CT/MRI. Sensitivity and specificity for detecting primary lymph node involvement were 71 %/86 % for PET and 74 %/57 % for CT/MRI, resulting in an accuracy of 77 % with PET and 68 % with morphological imaging. In 23 pts histopathology revealed pT1 stages with tumor diameters < 12 mm. In 8 pts CT/MRI and in 10 pts PET failed to identify these small primary lesions. Detecting tumor recurrence (n = 37) PET showed a higher sensitivity (83 %), specificity (76 %) and accuracy (78 %) compared to CT/MRI (sensitivity: 67 %; specificity: 52 %; accuracy: 57 %). In 4/6 pts with unknown primary, imaging was able to identify a primary lesion (3/4 in FDG-PET, 2/4 in CT/MRI), in 2/6 patients even in the follow-up no primary tumor was found.

CONCLUSIONS

FDG-PET provides only minor additional information to morphological imaging concerning diagnosis of primary tumors. At a similar level of sensitivity, however, it seems to be more specific regarding the lymph node involvement. PET seems to be superior to CT/MRI in detecting tumor recurrence as well as occult primary tumors in pts with known cervical lymph node metastases.

[Value of secondary coronal reconstructions in computed tomography of the paranasal sinuses]

INTRODUCTION

Before sinus surgery, computed tomography (CT) of the paranasal sinuses and anterior skull base is a standard procedure in the diagnostic evaluation. However, coronal sections necessary for the analysis of the complex anatomy of this region are often not applicable in multiple injured or elderly patients due to the impossibility to maintain the required position for the coronal scans. Secondary coronal reconstruction of primary axially acquired scans could help to overcome this problem. This technique was, however, hampered so far by an insufficient resolution in case of conventional CT. We therefore compared the quality of primary coronally acquired conventional CT images with the resolution of multiplanar reformatted coronal images of primary axially acquired scans by means of a new CT generation, the Multidetector Computed Tomography (MDCT).

MATERIAL AND METHODS

10 patients were each examined with conventional CT or MDCT respectively. The quality of primary coronally acquired conventional scans (CT) versus secondary coronal reconstructions (MDCT) was compared by evaluating typical anatomic landmarks.

RESULTS

As compared to conventional CT, the coronal reconstruction of primary axially acquired scans by means of MDCT revealed an equal resolution and additionally no essential impairment by amalgam artefacts.

CONCLUSION

Our results demonstrate the excellent quality of secondary coronal reconstructions by means of MDCT in the CT evaluation of the paranasal sinuses and the anterior skull base as compared to primary coronally acquired images via conventional CT.

[Follow-up assessment of intratympanic gentamicin therapy and Saccotomia in Menière's Disease]

BACKGROUND

The intratympanic application of ototoxic antibiotics and saccotomia have been well documented in severe cases of one-sided Menière's disease for 30 years now. Both treatment methods are still subject to controversial discussion.

PATIENTS AND MATERIAL

This study includes 8 patients suffering from persistent one-sided Menière's disease after treatment with gentamicin application and additional saccotomia (n=2). We performed follow-up visits including the assessment of hearing ability, vestibular function and cranial MRI, 2-10 years after onset of treatment.

RESULTS

After therapeutic interventions 7 patients reported to be healed of their symptom vertigo. In 4 patients the gentamicin-treated vestibular organ did not respond to thermic stimulus at the time of follow-up examination. Auditory threshold shift was observed in 3 patients (1 permanent, 2 temporary), whereas hearing threshold improved in 2 patients. Tinnitus was attenuated in 3 patients, while 1 patient suffered from posttherapeutic onset of tinnitus. Morphological and structural changes due to Menière's disease and treatment procedures were ruled out by cranial MRI.

CONCLUSION

The intratympanic application of ototoxic medication is a safe and effective treatment method in severe cases of Menière's disease. Saccotomia should be considered as therapeutic regimen for persistent symptoms after repeated application of gentamicin.

CT and MR imaging of the normal and pathologic conditions of the facial nerve

Computed tomography (CT) and magnetic resonance imaging (MRI) are well established imaging modalities to examine the facial nerve as well as the course of the facial nerve itself. High spatial resolution is guaranteed not only in the x- and y-axis, but also in the z-axis using multislice spiral CT. With this technique, reformatted multiplanar images in oblique planes, avoiding additional examinations in the coronal plane, facilitate the delineation of the facial nerve canal. This is beneficial in patients with temporal bone trauma, malformation or osseous changes. MR has a superior soft-tissue contrast to CT that enables imaging of the facial nerve itself. Therefore the normal facial nerve as well as pathologic changes of the facial nerve is readily visualized from the brain stem to the parotid gland. This review article presents anatomy, pathology and imaging strategies in the diagnostics of the facial nerve.