Friedrich Goetz

Forensic imaging of projectiles using cone-beam computed tomography

In patients with gunshot injuries, it is easy to detect a projectile within the body due to the high-density of the object, but artefacts make it difficult to obtain information about the deformation and the exact location of the projectile in surrounding tissues. Cone-beam computed tomography (CBCT) is a new radiological imaging modality that allows radio-opaque objects to be localised and assessed in three dimensions. The full potential of the use of CBCT in forensic medicine has not yet been explored. In this study, three different modern projectiles were fired into the heads of pig cadavers (n=6) under standardised conditions. Tissue destruction and the location of the projectiles were analysed separately using CBCT and multi-slice computed tomography (MDCT). The projectiles had the same kinetic energy but showed considerable differences in deformation behaviour. Within the study groups, tissue destruction was reproducible. CBCT is less severely affected by metallic artefacts than MDCT. Therefore CBCT is superior in visualising bone destruction in the immediate vicinity of the projectile and projectile deformation, whereas MDCT allows soft tissue to be evaluated in more detail. CBCT is an improved diagnostic tool for the evaluation of gunshot injuries. In particular, it is superior to MDCT in detecting structural hard-tissue damage in the immediate vicinity of high-density metal projectiles and in identifying the precise location of a projectile in the body.

The vestibulocochlear nerve: aplasia and hypoplasia in combination with inner ear malformations

AbstractObjectiveTo determine features of hypoplasia and aplasia of the vestibulocochlear nerve (VCN) in combination with inner ear malformations (IEMs).MethodsIndex cases were retrospectively selected from all IEMs collected since 1995. CT and MRI data were reviewed by two neuroradiologists. The number and thickness of visible nerves in the cerebellopontine angle cistern and inside the internal auditory canal (IAC) were analysed.ResultsMR images for 176 patients with IEMs were analysed. Labyrinthine aplasia and otocyst deformity showed 100% correlation, and IAC malformations exhibited 92% correlation with VCN aplasia. Cochlear aplasia, complete aplasia of the semicircular canals, severe cochlear hypoplasia, common cavity, incomplete partition type 1 and mild cochlear hypoplasia showed decreasing degrees of correlation with hypoplasia of the VCN. The remaining types of IEM did not demonstrate VCN hypoplasia.ConclusionsCertain forms of IEM show 100% correlation with hypoplasia or aplasia of the VCN, while others correlate less strongly and some do not usually exhibit VCN hypoplasia. MRI should always be carried out for those forms often correlated with VCN hypoplasia.Key Points• Vestibulocochlear nerve deficiency can be strongly suspected in certain inner ear malformations • Bony cochlear aplasia and cochlear nerve aplasia are strongly correlated • In semicircular canal aplasia, hypoplasia of the vestibular nerve can be found • Before cochlear implantation, the type of any IEM should be fully understood

Appearance of hypoplastic cochleae in CT and MRI: a new subclassification

IntroductionHypoplastic cochleae are among the inner ear malformations more frequently encountered by radiologists; little detailed information is available on these, however. We present the first large series of hypoplastic cochleae and document imaging findings to better characterize this anomaly radiologically.MethodsWe used our electronic database to search for inner ear malformations described between 1995 and 2009 and extracted 81 ears (of 47 patients) with hypoplastic cochleae out of 289 patients with inner ear malformations. Two neuroradiologists evaluated the available CT and MRI data. Measurements of all inner ear structures were performed. Accompanying findings were listed.ResultsCochlear hypoplasia (58 ears, 32 patients) often involves not only the apical turn being reduced in size but also the basal turn being smaller in length. Additionally, 11 ears (eight patients) of hypoplastic cochleae with only a basal turn and five ears (four patients) of cochleae with only a small bud were identified. Non-classifiable hypoplastic cochleae (seven ears, five patients) were those with either a rudimentary or an absent basal turn or a “dwarf appearance” with no further partition.ConclusionsThe term “hypoplastic cochlea” is very general; a further division into severe and less severe forms based on the length and existence of cochlea turns is possible and can help enhance the comparison of CI outcome data. Measurements can help the less experienced radiologist to detect them more easily.

Intra-arterial thrombolysis using rt-PA in patients with acute stroke due to vessel occlusion of anterior and/or posterior cerebral circulation

IntroductionThe aim of our study was to evaluate the safety and efficacy of intra-arterial (IA) thrombolysis using recombinant tissue plasminogen activator (rt-PA) in patients with acute stroke due to occlusion in the anterior or posterior circulation.MethodsWe retrospectively analyzed the clinical and radiological data of 88 consecutive patients with acute ischemic stroke who underwent emergency cerebral angiography for the purpose of subsequent IA thrombolysis. The neurological deficit on admission and discharge was graded using the National Institutes of Health Stroke Scale (NIHSS) score. Baseline computer tomography (CT) scans were examined for any signs indicative of cerebral ischemia. The angiographic findings were classified according to the Thrombolysis in Myocardial Infarction (TIMI) score for myocardial infarction. Follow-up CT scans were examined for hemorrhagic complication.ResultsOf the 88 patients who underwent IA thrombolysis, 63 presented with complete or partial arterial occlusion in the suspected perfusion area. In these 63 patients, the median NIHSS score dropped from 15 points on admission to 10 points at discharge. The recanalization rate was 52.6% for partial and complete reperfusion. In-hospital mortality was 20.6% (9.1% for carotid, 44.4% for basilar territory occlusion). Intracerebral bleeding (ICB) occurred in 38.6% of the patients with occlusion in the anterior circulation, resulting in these patients presenting a worse clinical outcome than those without ICB. Only minor extracranial bleedings occurred in 20.6% of patients. Patients with ICB had a significantly higher frequency of ischemic signs on the baseline CT scan.ConclusionOcclusion of a cerebral artery is present in about 75% of the patients eligible for thrombolytic therapy. Intra-arterial thrombolysis using rt-PA in patients with acute ischemic stroke can achieve re-vascularization, although ICB remains the major risk factor affecting its efficacy.

Improved imaging of Cochlear nerve hypoplasia using a 3-tesla variable flip-angle turbo spin-echo sequence and a 7-cm surface coil

Magnetic resonance imaging of the temporal bone has an important role in decision making with regard to cochlea implantation, especially in children with cochlear nerve deficiency. The purpose of this study was to evaluate the usefulness of the combination of an advanced high‐resolution T2‐weighted sequence with a surface coil in a 3‐Tesla magnetic resonance imaging scanner in cases of suspected cochlear nerve aplasia.

Radiological diagnosis of incomplete partition type I versus type II: significance for cochlear implantation

AbstractObjectivesTo investigate an extended cohort of patients with incomplete partition (IP) and examine the adequacy of the existing classifications based on radiological criteria and on their implications for cochlear implantation.MethodsPatients with IP admitted to a tertiary referral centre during the period 2000–2010 were retrospectively examined. The subjects were initially classified into IP-I, IP-II and atypical cases. For cochlear implant recipients relevant aspects were analysed.ResultsEighty-three ears (49 patients) with IP were found, 19 with IP-I, 54 with IP-II and 10 atypical. Thirty-three patients received a cochlear implant (11 with IP-I, 19 with IP-II and three atypical) achieving heterogeneous though mostly promising results. Cerebrospinal fluid gushing was the commonest surgical complication, particularly in cases of IP-I. In general, patients with IP-II performed better than those with IP-I.ConclusionsCochlear implantation promises adequate hearing rehabilitation for most patients with IP. As we move from IP-I to IP-II better results and lower risk for gushing shall be expected. Based on radiological findings we suggest a modified classification into IP-I, atypical IP-I (with large vestibular aqueduct (LVA) and better partition), IP-II (Mondini deformity) and atypical IP-IIa (without LVA) and b (without LVA but with semicircular canal dysplasia).Key Points• Radiological (CT and MR) features are of crucial importance for cochlear implantation • Imaging can identify two types of incomplete cochlear partition and atypical cases • Detailed pre-operative radiological assessment can help predict complications and outcome • A more comprehensive radiological classification of these anomalies is proposed

From labyrinthine aplasia to otocyst deformity.

IntroductionInner ear malformations (IEMs) are rare and it is unusual to encounter the rarest of them, namely labyrinthine aplasia (LA) and otocyst deformity. They do, however, provide useful pointers as to the early embryonic development of the ear. LA is characterised as a complete absence of inner ear structures. While some common findings do emerge, a clear definition of the otocyst deformity does not exist. It is often confused with the common cavity first described by Edward Cock. Our purpose was to radiologically characterise LA and otocyst deformity.MethodsRetrospective analysis of CT and MRI data from four patients with LA or otocyst deformity. Middle and inner ear findings were categorised by two neuroradiologists.ResultsThe bony carotid canal was found to be absent in all patients. Posterior located cystic structures were found in association with LA and otocyst deformity. In the most severe cases, only soft tissue was present at the medial border of the middle ear cavity. The individuals with otocyst deformity also had hypoplasia of the petrous apex bone.ConclusionsThese cases demonstrate gradual changes in the two most severe IEMs. Clarification of terms was necessary and, based on these findings, we propose defining otocyst deformity as a cystic structure in place of the inner ear, with the cochlea, IAC and carotid canal absent. This condition needs to be differentiated from the common cavity described by Edward Cook. A clear definition of inner ear malformations is essential if outcomes following cochlear implantation are to be compared.

Inner ear anatomy in Waardenburg syndrome: radiological assessment and comparison with normative data.

OBJECTIVE As patients with Waardenburg syndrome (WS) represent potential candidates for cochlear implantation, their inner ear anatomy is of high significance. There is an ongoing debate whether WS is related to any inner ear dysplasias. Our objective was to evaluate radiologically the inner ear anatomy in patients with WS and identify any temporal bone malformations. METHODS A retrospective case review was carried out in a tertiary, referral center. The high resolution computed tomography (HRCT) scans of the temporal bone from 20 patients (40 ears) with WS who were managed for deafness in a tertiary referral center from 1995 to 2012 were retrospectively examined. Measurements of 15 different inner ear dimensions, involving the cochlea, the vestibule, the semicircular canals and the internal auditory meatus, as well as measurements of the vestibular aqueduct, were performed independently by two neuroradiologists. Finally, we compared the results from the WS group with a control group consisting of 50 normal hearing subjects (100 ears) and with previously reported normative values. RESULTS Inner ear malformations were not found in any of the patients with WS. All measured inner ear dimensions were within the normative values compiled by our study group as well as by others. CONCLUSIONS Inner ear malformations are not characteristic for all types of WS; however, certain rare subtypes might be related to inner ear deformities. Normative cochleovestibular dimensions that can help in assessing the temporal bone anatomy are provided.

Aplasia of the cochlea: radiologic assessment and options for hearing rehabilitation.

Objective Hearing rehabilitation of patients with severe inner ear malformations remains controversial. Our objective was to describe the radiologic findings of aplasia of the cochlea (AC) and evaluate the existing therapeutic options in such patients. Study Design Retrospective cohort study. Setting Tertiary referral center. Patients Pediatric and adult patients with AC evaluated at our institution from 1995 to 2010. Interventions The precise radiologic findings were identified using high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) scans of the inner ear. In cases of auditory implantation on the AC side, the achieved outcome was recorded using categories of auditory performance (CAP). Related surgical aspects were analyzed. Results Twenty-three patients (28 ears) with AC were found. In 5 patients AC was bilateral. The remaining unilateral cases had contralateral normal ears (2 patients), cochlea hypoplasia (5 patients), common cavity (6 patients), incomplete partition Type I (4 patients), and atresia of the internal auditory canal (1 patient). Four patients (3 bilateral, 1 unilateral ACs) were treated with cochlear implants in ears with AC, and 1 patient underwent auditory brainstem implantation. All implanted patients achieved speech perception with limited vocabulary (CAP scores between 4 and 5). Conclusion AC is defined as the total absence of the cochlea, with a present, although malformed, vestibule. Although a distinct auditory nerve was not seen in these cases of AC, results following cochlear implantation suggest functional cochlear nerve fibers in the remaining dysplastic inner ear structures. In selected cases, cochlear implantation may be a reasonable option for the habilitation of deafness associated with AC.

Aberrant course of the intracranial facial nerve in cases of atresia of the internal auditory canal (IAC)

IntroductionThe aim of this study is to describe the morphology of the rare malformation that is atresia of the internal auditory canal (IAC) and determine the course of the facial nerve in cases of normal facial nerve function.MethodsIndex cases were retrospectively selected from our electronic database in which all inner ear malformations presenting to a tertiary referral center between 1995 and 2010 are collected. Computed tomography (CT) data and magnetic resonance (MR) images were reviewed by two neuroradiologists. An otolaryngologist analyzed the patients’ clinical data.ResultsNine ears of six patients (three bilateral, three unilateral) with atresia of the IAC were identified. All patients presented with sensory neural hearing loss. Two of these unilaterally affected patients had facial nerve palsy. In the other seven cases of complete atresia of the IAC, the facial nerve was dislocated in its cisternal segment close to the trigeminal nerve. Where the nerve fibers enter the Gasserian ganglion, the facial nerve takes a sharp lateral turn and enters a minute canal by which it reaches the geniculate ganglion. In the two ears with facial nerve palsy, this pathway could not be identified.ConclusionsIn atresia of the IAC, the facial nerve takes a ventral and superior course, with its own canal starting at the point where the trigeminal nerve enters the Gasserian ganglion. Facial nerve palsy points to absence of this aberrant temporal facial nerve canal.