Effect of head position on cochlear implant MRI artifact.

PURPOSE: A new generation of cochlear implant (CI) magnets and specific surgical techniques (e.g., implant positioning) has changed the relationship between a CI and magnet resonance imaging (MRI). MRI allows a pain free in vivo evaluation of the inner ear fluid state and internal auditory canal after the insertion of an electrode. The aim of this study is to evaluate how the patient's head position in the MRI scanner influences the CI magnet-related artefact. METHODS: We performed in vivo measurement of MRI artefacts at 3 T with a CI system containing a bipolar diametrical magnet. The implant magnet was positioned with a head bandage at different positions from the nasion and external auditory canal in three volunteers. We used a turbo spin echo (TSE) T2w sequence on the axial and coronal planes and observed three positions: (1) regular position, (2) chin to chest (anteflexion), and (3) hyperextension (retroflexion). RESULTS: By comparing the positions, anteflexion of the cervical spine in a chin-to-chest position allowed us to place the artefact in a more apical position from the IAC in the coronal plane. The hyperextension of the cervical spine position shifts the artefact father towards the cochlea's direction. CONCLUSION: The head's position can influence the location of MRI artefacts. In cases where the artefact diminished the IAC or cochlea, anteflexion of the cervical spine in the chin-to-chest position of the head in the MRI scanner should be attempted to allow a visualization of the IAC.

[A rare pathology of the petrous part of the temporal bone: adenoma of the middle ear]. / Eine seltene Pathologie des Felsenbeins: Das Adenom des Mittelohres.

Adenomas are very rare tumors of the middle ear. They are benign neoplasms originating from the glandular components of the mucous membrane of the middle ear. The middle ear adenoma was first described by Hyams and Michaels in 1976, which was named an adenomatous tumor. This article reports the case of a 50-year-old female patient, who presented with recurrent right-sided dull otalgia and pulse synchronous tinnitis, which began 1 year prior to presentation, with the suspected diagnosis of a glomus tympanicum tumor. Following the otorhinolaryngological examination and imaging an unclear mesotympanal space-occupying lesion was detected. A transmeatal endoscopic complete removal of the tumor was carried out. The histopathological investigations enabled the diagnosis of an adenoma of the middle ear. Adenomas are a rare differential diagnosis of tumors of the middle ear. In cases with a suitable localization an adequate exposure and removal of this rare tumor can be achieved by a transmeatal endoscopic access.

Multimodality treatment for poorly differentiated neuroendocrine head and neck carcinomas--a single institution experience.

Poorly differentiated head and neck neuroendocrine neoplasms are very rare. Surgical resection alone is insufficient to control the disease because of the high incidence of metastases. However, due to the lack of randomised clinical trials, treatment recommendations for this cancer vary considerably and are based on a limited number of small retrospective studies. We performed a retrospective analysis of all patients treated at our institution between 2003 and 2011. We assessed the stage of disease, type of therapy, toxicity, treatment response, time to progression and overall survival for all cases. Ten patients received combined modality treatment with chemotherapy in addition to surgery or radiation or both. According to Response Evaluation Criteria In Solid Tumours (RECIST) criteria, six of nine evaluable patients achieved complete remission and three patients had a partial remission. The mean duration of response was 358 days, with a range from 141 to 1080 days. The overall 1-year survival rate was 88%; however, only approximately 50% of patients were alive after 2 years. Multimodality treatment concepts induce high initial remission rates in poorly differentiated neuroendocrine head and neck carcinomas. However, the time to relapse is usually short, and therefore long-term prognosis of this rare head and neck tumour remains poor.

Ipsilateral Vestibular Schwannoma after Cochlear Implantation.

OBJECTIVE: The vestibular schwannoma incidence rate is approximately 4.2 per 100,000/year. Thus far, about 700,000 cochlear implantations have been performed worldwide; therefore, the occurrence of vestibular schwannoma postcochlear implantations can be assumed to be infrequent. Recent developments allow safe observation and surveillance of the implanted-side internal auditory canal (IAC) and cochlea by magnetic resonance imaging (MRI), even after cochlear implantation. Patients. A 71-year-old woman with sudden hearing loss and a contralateral vestibular schwannoma without clinical and genetic signs of neurofibromatosis type II. Intervention(s). Ipsilateral cochlear implantation and contralateral vestibular schwannoma extirpation with regular tumor follow-up. Main Outcome Measure(s). Comparison of ipsilateral pre and postcochlear implantation 3T MRI T1 GAD. RESULTS: We observed a tumor growing at the fundus of the internal auditory canal 1 year after cochlear implantation on the ipsilateral side. Although first detected after cochlear implantation beside a known vestibular schwannoma on the contralateral side, a scan slice thickness of 2 mm cannot fully exclude the preoperative persistence of a small tumor. Based on the clinical findings and after genetic exclusion of NFII, the patient was classified as a NFII mosaic type. CONCLUSION: Even after cochlear implantation, tumors in the IAC causing vertigo, facial palsy, and affecting the audiologic outcome can be detected by MRI. The MRI slice thickness used before cochlear implantation should be under 2 mm.

Evaluation of cochlear implant electrode scalar position by 3 Tesla magnet resonance imaging.

The estimation of scalar electrode position is a central point of quality control during the cochlear implant procedure. Ionic radiation is a disadvantage of commonly used radiologic estimation of electrode position. Recent developments in the field of cochlear implant magnets, implant receiver magnet position, and MRI sequence usage allow the postoperative evaluation of inner ear changes after cochlear implantation. The aim of the present study was to evaluate the position of lateral wall and modiolar cochlear implant electrodes using 3 T MRI scanning. In a prospective study, we evaluated 20 patients (10× Med-El Flex 28; 5× HFMS AB and 5× SlimJ AB) with a 3 T MRI and a T2 2D Drive MS sequence (voxel size: 0.3 × 0.3 × 0.9 mm) for the estimation of the intracochlear position of the cochlear implant electrode. In all cases, MRI allowed a determination of the electrode position in relation to the basilar membrane. This observation made the estimation of 19 scala tympani electrode positions and a single case of electrode translocation possible. 3 T MRI scanning allows the estimation of lateral wall and modiolar electrode intracochlear scalar positions.

Comparison of Cochlear Implant Magnets and Their MRI Artifact Size.

INTRODUCTION: Recent developments regarding cochlear implant magnets (e.g., a bipolar diametral magnet) and refined surgical techniques (e.g., implant positioning) have had a significant impact on the relation between cochlear implants and MRIs, making the reproducible visibility of cochlea and IAC possible. MRI scanning has changed from a contraindication to a diagnostic tool. Magnet artifact size plays a central role in the visual assessment of the cochlea and IAC. OBJECTIVE: The aim of this study is to compare the CI magnet-related maximum artifact sizes of various cochlea implant systems. MATERIALS AND METHODS: We performed an in vivo measurement of MRI artifacts at 1.5 and 3 Tesla with three cochlear implant magnet systems (AB 3D, Medel Synchrony, and Oticon ZTI). The implant, including the magnet, was positioned with a head bandage 7.0 cm and 120° from the nasion, external auditory canal. We used a TSE T2w MRI sequence on the axial and coronal plains and compared the artifacts in two volunteers for each tesla strength. RESULTS: Intraindividual artifact size differences between the three magnets are smaller than interindividual maximum artifact size differences. 3 T MRI scans, in comparison to 1.5 T MRI scans, show a difference between soft artifact areas. CONCLUSION: We observed no major difference between maximum implant magnet artifact sizes of the three implant magnet types.

Enhancement of cerebral diseases: how much contrast agent is enough? Comparison of 0.1, 0.2, and 0.3 mmol/kg gadoteridol at 0.2 T with 0.1 mmol/kg gadoteridol at 1.5 T.

RATIONALE AND OBJECTIVES: To determine the clinical dose of gadoteridol (ProHance, Bracco-Byk Gulden) to use for the assessment of blood-brain barrier breakdown on low-field magnetic resonance (MR) scanners that corresponds to a standard dose of gadoteridol on high-field MR scanners. METHODS: This prospective study was carried out at four centers. A total of 138 patients with suspected or known brain diseases underwent a routine head scan comprising precontrast T2-weighted turbo spin-echo and T1-weighted spin-echo sequences on a 1.5-T MR scanner. After administration of a standard dose of 0.1 mmol/kg gadoteridol, the T1-weighted scan was repeated after a delay of 15 to 20 minutes. For continuing the examination on a 0.2-T MR scanner (Magnetom OPEN, Siemens), a standard-dose T1 spin-echo sequence was started within 30 to 50 minutes of the first injection. Then two additional T1-weighted low-field sequences were each started 5 minutes after two additional doses of 0.1 mmol/kg gadoteridol. Eighty patients with enhancing lesions underwent an intraindividual comparison. Evaluation of the overall numbers of lesions detected and of lesion size and character was performed on-site as well as off-site by two independent readers. RESULTS: The single-dose, low-field sequence detected significantly fewer enhancing lesions (80/95 lesions; P < 0.05), particularly metastases and infarctions, than did the standard-dose, high-field sequence. No statistically relevant differences (reader 1: P = 1; reader 2: P = 0.8) were found between the double- and triple-dose, low-field sequences and the standard-dose, high-field sequence. Primary brain tumors were detected by all postcontrast sequences irrespective of the dose. CONCLUSIONS: At low field, the clinically equivalent dose to 0.1 mmol/kg gadoteridol at high field is 0.2 mmol/kg. A dose of 0.1 mmol/kg gadoteridol is less effective and cannot be recommended for use on extremely low-field scanners.

Familial pontocerebellar hypoplasia type I with anterior horn cell disease.

We report the association of pontocerebellar hypoplasia and anterior horn cell disease in three female siblings. One child presented with the classical clinical and neuropathological features of pontocerebellar hypoplasia with associated anterior horn cell disease, described by Barth as pontocerebellar hypoplasia type I. This patient showed polyhydramnios, congenital contractures, respiratory insufficiency, hypotonia, areflexia, listlessness and myoclonic seizures. Postmortem examination revealed a loss of neurons and reactive gliosis in the pontocerebellum and in addition anterior horn cell atrophy resembling Werdnig-Hoffmann disease. Another sibling demonstrated the same clinical symptoms. However neuropathological findings showed evidence for pontocerebellar hypoplasia only. The third sibling was examined after induced fetal abortion because of prenatally diagnosed arthrogryposis. Anterior horn cell disease was obvious histologically whereas pontocerebellar hypoplasia could not be demonstrated due to cerebral autolysis. The similar clinical and neuropathological findings in the three reported siblings suggest a common genetic defect with different patterns of pontocerebellar hypoplasia and associated anterior horn cell disease. The gene defect of this rare disorder is still unknown. The 'survival motor neuron' gene of spinal muscular atrophy was not found in these three siblings.

Acquired thromboatheromatous coarctation of the aorta: acquired coarctation of the aorta.

BACKGROUND: Atheromatosis of the thoracic aorta and aortic arch is a well established source of systemic embolism. Acquired atheromatous coarctation of the aortic arch is a rare finding and not well documentated so far. CASE REPORT AND FINDINGS: Two patients presenting with intermittent claudication of the lower extremities were identified as having thromboatheromatous coarctation of the aortic arch as visualized by magnetic resonance tomography, fast CT scan, transesophageal echocardiography, cardiac catheterization and aortography. All findings including invasive hemodynamics resembled congenital coarctation of the aorta. One patient was treated surgically, while the other refused surgery and received long-term anticoagulation. CONCLUSION: Atheromatosis of the thoracic aorta and aortic arch not only cause systemic embolism, but may lead to the clinical and hemodynamic picture of coarctation of the aortic arch.

Renal perfusion imaging using contrast-enhanced phase-inversion ultrasound.

AIMS: We evaluated different techniques of contrast-enhanced phase-inversion ultrasound to visualize renal perfusion in native kidneys and kidney transplants. MATERIALS AND METHODS: Contrast-enhanced phase inversion ultrasound with different levels of mechanical index and frame rate was performed in 20 kidneys of 13 healthy volunteers. In addition, five dysfunctioning kidneys of patients with chronic renal failure, five functionally intact kidney transplants, three kidney transplants with compensated renal failure, and two kidney transplants with acute rejection were studied. Analysis using a software algorithm for time-resolved perfusion imaging was compared to single-image analysis performed by three independent radiologists. RESULTS: Optimal depiction of renal perfusion was achieved only by using a mechanical index, which was high enough to destroy the microbubbles of the contrast agent (burst imaging) combined with a low frame rate (0.5 images/second). Renal cortex and medulla showed a homogeneous enhancement in kidneys of healthy volunteers and functionally intact renal transplants. Dysfunctioning kidneys of patients with chronic renal failure as well as kidney transplants with compensated renal failure or acute rejection showed a significantly reduced level of enhancement. Computer-assisted time-resolved perfusion analysis was not superior to single-image analysis. CONCLUSION: Renal perfusion patterns of normal and abnormal tissue can be visualized using contrast-enhanced phase-inversion ultrasound imaging.

Results of a prospective multicenter study for evaluation of the diagnostic quality of an open whole-body low-field MRI unit. A comparison with high-field MRI measured by the applicable gold standard.

OBJECTIVE: To evaluate the diagnostic quality of an open whole-body low-field MRI scanner compared to high-field scanners. MATERIALS AND METHODS: Over a period of 3 months, 401 patients with diseases of the kidney (n = 78), the shoulder (n = 122), the spine (n = 105) and the cerebrum (n = 96) were prospectively evaluated in four participating centers. They all underwent clinical evaluation, low-field and high-field MRI examination and surgical or follow-up confirmation of diagnosis. Clinical, histopathologic, high-field and low-field MRI diagnoses were recorded in standardized questionnaires that were centrally evaluated. Statistical evaluation comprised two parts: ROC analysis assessed accuracy of MRI and clinical diagnoses; furthermore rates of concordance of high- and low-field MRI diagnosis were calculated. RESULTS: We found no statistically relevant difference in high-field MRI diagnosis compared to low-field MRI diagnostic accuracy measured by clinical or surgical gold standard in three of the four regions examined; in cerebral examinations there was a small yet significant advantage for the high-field systems (P = 0.01). CONCLUSION: We conclude that the open low-field scanner we evaluated using clinical and surgical gold standard as reference is able to achieve comparable diagnostic accuracy compared to high-field scanners at lower costs and greater patient comfort. Limitations due to field strength (signal-to-noise ratio, resolution, scan time) seem to be relevant only in a very small number of cases that warrant high-field examination.

[MR-angiography (MRA) in deep leg and pelvic venous thrombosis: a comparison with phlebography]. / MR-Angiographie (MRA) der tiefen Bein- und Beckenvenenthrombose: Vergleich mit der Phlebographie.

MRA by means of flow-phased gradient echo sequences is a valuable addition to phlebography for showing the extent of thrombosis in the veins of the pelvis and lower limbs. In eight out of 32 patients in whom the extent of deep vein thrombosis was not clearly shown by phlebography, it was possible to demonstrate the involvement of the inferior vena cava. Three of these patients had bilateral pelvic vein thrombosis. In seven out of 32 cases, thrombosis on the opposite side, which was not apparent clinically, could be demonstrated by MRA. Seven out of 32 patients showed involvement of the internal iliac vein. MRA is also valuable for observing the effect of treatment.

[Manganese dipyridoxal diphosphate as a new contrast medium in the MRT of benign and malignant pancreatic tumors: initial clinical findings]. / Mangan-Dipyridoxal-Diphosphat als neues Kontrastmittel in der MRT von benignen und malignen Pankreastumoren: Erste klinische Erfahrungen.

MnDPDP is a new intracellular contrast medium of which 50% is excreted through the bile; its acceptability and effect on MR images was studied in 21 patients, 18 of whom had malignant and three benign tumours of the pancreas. Spin echo T1 images (SE-T1: TR = 500 ms; TE = 15 ms) showed a 20% increase in signal to noise ratio (S/N) (p = 0.059) and a 90% increase in contrast to noise ratio (C/N) (p = 0.0027). In gradient T1 images (GE-T1: TR = 100 ms; TE = 6 ms; flip angle = 70 degrees) there was an increase of S/N of 70% (p < 0.0001) and of the C/N of 200% (p < 0.0001). T2 weighted SE sequences were inferior to plain SE-T1 weighted sequences with regard to their S/N and C/N ratios. There were no significant clinical complications or biochemical changes in the blood or urine. A subjective side effect in three patients was a feeling of heat. MnDPDP is a well tolerated and effective contrast medium for MRT of pancreatic tumours.

[A technic of MRT-guided abdominal drainage with an open low-field magnet. Its feasibility and the initial results]. / Technik der MRT-gesteuerten abdominellen Drainage an einem offenen Niederfeldmagneten. Durchführbarkeit und erste Ergebnisse.

PURPOSE: To test the practicality of MRT-aided drainage using an open low-field magnet and to report on the early clinical results. METHODS: So far seven patients have been treated (four subphrenic abscesses, two psoas abscesses and one pancreatic pseudocyst). The planning of the approach and catheter insertion were carried out under MRT control (Magnetom Open, 0.2 T). Subsequent treatment was controlled by CT and fluoroscopy. Initial puncture was carried out with a non-magnetic 18 gauge Chiba needle. The drainage catheter was introduced by Seldinger's technique in six cases and with a trocar in one patient. RESULTS: In all seven patients drainage could be started successfully. The design of the magnet and coils permitted adequate accessibility of the patient. There were no problems in visualising the puncture needle. Controlling the position of the catheter by MRT was, however, difficult. CONCLUSION: The first two steps in abscess drainage (planning the approach and inserting the catheter) can be carried out under MRT control. For further catheter control and observing the course of the disease we presently prefer CT or fluoroscopy.

[Technique of MRT-guided core biopsy in the abdomen using an open low-field scanner: feasibility and initial clinical results]. / Technik der MRT-gesteuerten Stanzbiopsie im Abdomen an einem offenen Niederfeldgerät: Durchführbarkeit und erste klinische Ergebnisse.

PURPOSE: Due to high soft-tissue contrast and multiplanar imaging capabilities MRI is an interesting modality to perform image-guided biopsies. We checked on the feasibility of MR-guided core biopsies of abdominal masses with an open low-field scanner (0.2 Tesla; vertical field axis). METHODS: 9 patients underwent MR-guided biopsies of abdominal target lesions (6 focal liver lesions, two adrenal masses, one pelvic mass). Different MR-compatible core biopsy instruments were used (needle diameters 14G-18G). MR scans during the procedures were obtained applying T1-weighted gradient echo sequences suitable for breath-hold imaging. RESULTS: In each case, needle guidance was reliable, so that the biopsy instrument could be positioned correctly. Multiplanar imaging capabilities enabled even angled approaches to upper abdominal masses to be realized safely. The combination of magnet design and table design offered suitable access to the patient. CONCLUSION: Using an open low-field scanner, MR-guided core biopsies of abdominal masses are practicable.

[Comparative magnetic resonance imaging of renal space-occupying lesions with a high and low field MRI system]. / Vergleichende magnetresonanztomographische Darstellung renaler Raumforderungen an einem Hoch- und einem Niederfeld-MRT-System.

PURPOSE: A prospective study of the diagnostic accuracy and image quality of two MRI systems in the detection of renal tumors was investigated. MATERIALS AND METHODS: 34 patients with the clinical suspicion of a space-occupying renal lesion were examined by MRI with a low field (0.2 Tesla magnet) and a high field (1.5 Tesla magnet) for comparison. An "informed" and a "blind" observer evaluated all of the MR images. In addition, the signal-to-noise and contrast-to-noise ratios were evaluated as second quality parameters. RESULTS: In 29 cases the results could be compared with a confirmed release diagnosis. Diagnostic accuracy was comparable with both systems (Sensitivity for both observer on LF apparatus: 83%, HF apparatus: 81%) although the signal-to-noise and contrast-to-noise ratios were significantly poorer at low field. CONCLUSIONS: The low field system in comparable to the high field MRI for detection and differentiation of renal space-occupying lesions.

Changes of fascia and muscles before and 12 months after successful treatment of recalcitrant venous leg ulcers by shave therapy.

BACKGROUND: In chronic venous insufficiency (CVI) III typical changes of skin, subcutaneous tissue, fascia and muscle can be found. It was believed, that the thickening of the fascia is irreversible and it has been postulated that the degeneration of muscles is causative for the persistence of recalcitrant leg ulcers. PATIENTS AND METHODS: By computed tomography (CT) and magnetic resonance imaging (MRI) 8 patients with therapy resistant venous ulcers were examined. Changes of fascia and muscles were determined preoperatively and 12 months after successful shave therapy. RESULTS: By CT a thinning of the preoperatively thickened fascia could be demonstrated in all patients one year after surgery. Before shave therapy MRI showed that the fascia was not only thickened and blurred, but also had fluid accumulations perifascial. 12 months after therapy the fascia was thinner and sharply demarcated. The fluid was either absent or distinctively reduced. Referring to the thickness of fascia an average decrease of 0.084 cm (0.03-0.17 cm) was observed. Before surgery the muscles showed a fatty degeneration as a sign of atrophy; with CT and MRI no changes could be demonstrated after one year in all patients. CONCLUSION: The results after one year demonstrate for the first time, that the changes of the fascia in CVI III are reversible and that there is no direct correlation between the degeneration of muscles and the persistence of venous leg ulcers.

[Differential diagnosis in descending perineum syndrome]. / Differenzialdiagnostik der Beckenbodeninsuffizienz.

Clinical symptoms in descending perineum syndrome show considerable variations, ranging from obstructed defecation to combined fecal and urinary incontinence and including different types of prolapse. Differential diagnosis has to compete with this complexity. Common pelvic floor disorders associated with descending perineum are rectocele, rectal prolapse, enterocele, and sigmoidocele. Standardized diagnostic tools include detailed history and clinical examination with proctorectoscopy as well as anorectal manometry, endoanal ultrasound, defecography, and dynamic MR of the pelvic floor. The diagnosis and proposed therapy have to be developed within an interdisciplinary concept.

Anatomical accuracy in medical 3D modeling.

In complex surgery, medical modeling has become an accepted tool for diagnosis, simulation and the planning of surgical interventions [1]. However, the question concerning the accuracy of the model, i.e. the equivalence between the model itself on the one hand and the original anatomical situation on the other hand, remains unanswererd in the current literature.