Staging clavicular development on MRI : pitfalls and suggestions for age estimation

Background MRI of the clavicle's sternal end has been studied for age estimation. Several pitfalls have been noted, but how they affect age estimation performance remains unclear. Purpose/Hypothesis To further study these pitfalls and to make suggestions for a proper use of clavicle MRI for forensic age estimation. Our hypotheses were that age estimation would benefit from 1) discarding stages 1 and 4/5; 2) including advanced substages 3aa, 3ab, and 3ac; 3) taking both clavicles into account; and 4) excluding morphological variants. Study Type Prospective cross-sectional. Population Healthy Caucasian volunteers between 11 and 30 years old (524; 277 females, 247 males). Field Strength/Sequence 3T, T-1-weighted gradient echo volumetric interpolated breath-hold examination (VIBE) MR-sequence. Assessment Four observers applied the most elaborate staging technique for long bone development that has been described in the current literature (including stages, substages, and advanced substages). One of the observers repeated a random selection of the assessments in 110 participants after a 2-week interval. Furthermore, all observers documented morphological variants. Statistical Tests Weighted kappa quantified reproducibility of staging. Bayes' rule was applied for age estimation with a continuation ratio model for the distribution of the stages. According to the hypotheses, different models were tested. Mean absolute error (MAE) differences between models were compared, as were MAEs between cases with and without morphological variants. Results Weighted kappa equaled 0.82 for intraobserver and ranged between 0.60 and 0.64 for interobserver agreement. Stages 1 and 4/5 were allocated interchangeably in 4.3% (54/1258). Age increased steadily in advanced substages of stage 3, but improvement in age estimation was not significant (right P = 0.596; left P = 0.313). The model that included both clavicles and discarded stages 1 and 4/5 yielded an MAE of 1.97 years, a root mean squared error of 2.60 years, and 69% correctly classified minors. Morphological variants rendered significantly higher MAEs (right 3.84 years, P = 0.015; left 2.93 years, P = 0.022). Data Conclusion Our results confirmed hypotheses 3) and 4), while hypotheses 1) and 2) remain to be investigated in larger studies. Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019

The influence of motion artefacts on magnetic resonance imaging of the clavicles for age estimation

Purpose To determine how motion affects stage allocation to the clavicle's sternal end on MRI. Materials and methods Eighteen volunteers (9 females, 9 males) between 14 and 30 years old were prospectively scanned with 3-T MRI. One resting-state scan was followed by five intentional motion scans. Additionally, a control group of 72 resting-state scans were selected from previous research. Firstly, six observers allocated developmental stages to the clavicles independently. Secondly, they re-assessed the images, allocating developmental statuses (immature, mature). Finally, the resting-state scans of the 18 volunteers were assessed in consensus to decide on the "correct" stage/status. Results were compared between groups (control, prospective resting state, prospective motion), and between staging techniques (stages/statuses). Results Inter-observer agreement was low (Krippendorff alpha 0.23-0.67). The proportion of correctly allocated stages (64%) was lower than correctly allocated statuses (83%). Overall, intentional motion resulted in fewer assessable images and less images of sufficient evidential value. The proportion of correctly allocated stages did not differ between resting-state (64%) and motion scans (65%), while correctly allocated statuses were more prevalent in resting-state scans (83% versus 77%). Remarkably, motion scans did not render a systematically higher or lower stage/status, compared to the consensus. Conclusion Intentional motion impedes clavicle MRI for age estimation. Still, in case of obvious disturbances, the forensic expert will consider the MRI unsuitable as evidence. Thus, the development of the clavicle as such and the staging technique seem to play a more important role in allocating a faulty stage for age estimation

Forensic age estimation based on magnetic resonance imaging of third molars : converting 2D staging into 3D staging

Background: Established methods to stage development of third molars for forensic age estimation are based on the evaluation of radiographs, which show a 2D projection. It has not been investigated whether these methods require any adjustments in order to apply them to stage third molars on magnetic resonance imaging (MRI), which shows 3D information. Aim: To prospectively study root stage assessment of third molars in age estimation using 3 Tesla MRI and to compare this with panoramic radiographs, in order to provide considerations for converting 2D staging into 3D staging and to determine the decisive root. Subjects and methods: All third molars were evaluated in 52 healthy participants aged 14-26 years using MRI in three planes. Three staging methods were investigated by two observers. In sixteen of the participants, MRI findings were compared with findings on panoramic radiographs. Results: Decisive roots were palatal in upper third molars and distal in lower third molars. Fifty-seven per cent of upper third molars were not assessable on the radiograph, while 96.9% were on MRI. Upper third molars were more difficult to evaluate on radiographs than on MRI (p <. 001). Lower third molars were equally assessable on both imaging techniques (93.8% MRI, 98.4% radiograph), with no difference in level of difficulty (p = .375). Inter- and intra-observer agreement for evaluation was higher in MRI than in radiographs. In both imaging techniques lower third molars showed greater inter- and intra-observer agreement compared to upper third molars. MR images in the sagittal plane proved to be essential for staging. Conclusion: In age estimation, 3T MRI of third molars could be valuable. Some considerations are, however, necessary to transfer known staging methods to this 3D technique

Age estimation based on MRI of the third molars: transferring 2D staging into 3D staging

Purpose: To prospectively evaluate the use of 3T MRI of the third molars in age estimation. Materials and methods: In 52 healthy participants aged 14 – 26 years, MR images in three planes of all third molars were evaluated by two observers. In sixteen of them, MRI findings could be compared with findings on panoramic radiographs. Three staging methods were applied: Demirjian (1973), Köhler (1994) and Olze (2010). Results: The Olze method could not be applied, while both others could. In upper third molars the palatal root was considered decisive on MRI. In lower third molars this was the distal root. The majority of upper third molars (59.4%) was not assessable on panoramic radiograph, while all of them were on MRI. For assessable upper third molars the evaluation on radiography was more difficult than on MRI (P < 0.001). Lower third molars were assessable on both imaging techniques, with no difference in level of difficulty. Inter- and intra-observer agreement for evaluation was higher in MRI than in panoramic radiographs. In both imaging techniques lower third molars showed greater inter- and intra-observer agreement than upper third molars. MR images in the sagittal plane proved to be essential for staging. Axial and coronal images contributed to the staging only in a few cases, when the molar was tilted or when the apex was unclear on sagittal images. Conclusions: In age estimation, 3T MRI of third molars can be valuable. Some considerations are however necessary to transfer known staging methods to this 3D technique

Magnetic resonance imaging of the third molars: developing a protocol suitable for age estimation

Purpose: To develop a clinically feasible MRI protocol – using standard commercial 3T MR hardware – to visualize all four third molars for age estimation, with particular attention to distinguishing the highest developmental stages. Materials and methods: In vivo scans of eight volunteers aged 17 – 24 years and ex vivo scans of porcine jaws were performed to make a stepwise selection of adequate sequences. A bilateral four-channel flexible surface head coil was used. The maximum acceptable acquisition time was set at seven minutes. Two observers evaluated the suitability of the images. Results: T2-weighted images were preferred to T1-weighted images. To clearly distinguish root apices in (almost) fully developed third molars a spatial resolution of 0.30 x 0.30 mm² was necessary. Within the limited acquisition time only a TSE T2 sequence generated images with sufficient resolution. Thin slice TSE T2 and TSE 3D T2 sequences could not generate the desired resolution. A UTE sequence was tried, but could not be completed in vivo by the used hardware. Conclusion: Three Tesla MRI of the third molars is a feasible technique for age estimation, in which a TSE T2 sequence can provide the desired spatial resolution within a clinically acceptable acquisition time

Gas embolism following intraosseous medication application proven by post-mortem multislice computed tomography and autopsy

The post-mortem use of modern imaging techniques such as multislice computed tomography (MSCT) is becoming increasingly important as an aid for conventional autopsy. This article presents a case of a 4-month-old boy who died from sudden infant death syndrome (SIDS) with intravascular gas after an intraosseus medication application documented by post-mortem MSCT. It is most likely that the gas entered the body during resuscitation. This case emphasises the advantage of post-mortem imaging as a complementary aid for the autopsy. We conclude that during emergency treatment, the medical staff should be aware of the possibility of causing a gas embolism following intraosseus medication. Resuscitation with an inserted, disconnected intraosseous needle should be avoided

Magnetic resonance imaging of third molars : developing a protocol suitable for forensic age estimation

Background: Established dental age estimation methods in sub-adults study the development of third molar root apices on radiographs. In living individuals, however, avoiding ionising radiation is expedient. Studying dental development with magnetic resonance imaging complies with this requirement, adding the advantage of imaging in three dimensions. Aim: To elaborate the development of an MRI protocol to visualise all third molars for forensic age estimation, with particular attention to the development of the root apex. Subjects and methods:Ex vivo scans of porcine jaws and in vivo scans of 10 volunteers aged 17-25 years were performed to select adequate sequences. Studied parameters were T1 vs T2 weighting, ultrashort echo time (UTE), fat suppression, in plane resolution, slice thickness, 3D imaging, signal-to-noise ratio, and acquisition time. A bilateral four-channel flexible surface coil was used. Two observers evaluated the suitability of the images. Results: T2-weighted images were preferred to T1-weighted images. To clearly distinguish root apices in (almost) fully developed third molars an in plane resolution of 0.33 x 0.33 mm(2) was deemed necessary. Taking acquisition time limits into account, only a T2 FSE sequence with slice thickness of 2 mm generated images with sufficient resolution and contrast. UTE, thinner slice T2 FSE and T2 3D FSE sequences could not generate the desired resolution within 6.5 minutes. Conclusion: Three Tesla MRI of the third molars is a feasible technique for forensic age estimation, in which a T2 FSE sequence can provide the desired in plane resolution within a clinically acceptable acquisition time

Skeletal age estimation in the living : conventional radiography (CR) versus magnetic resonance imaging (MRI) and staging technique versus atlas method

Background: At present, forensic age estimation procedures in living adolescents and young adults rely on CR or computed tomography (CT) to visualize developing anatomical structures (1). Hand/wrist and clavicle development both contribute to the age estimate during the considered age range. Nevertheless, in several countries, only CR is considered for skeletal age estimation (2), while international recommendations advocate CT to visualize the clavicles (1). Moreover, MRI has been proposed as an alternative to CT to avoid exposure to ionizing radiation. Thus, a well-founded argumentation is needed to convince policy makers of the added value of MRI. Skeletal development is assessed by allocating stages or atlas standards, based on criteria of particular staging techniques or atlas methods, respectively. Although atlas methods seem more comprehensive, it is still unclear whether they should be preferred over staging techniques. Purpose: To compare CR and MRI of the left wrist and both clavicles for forensic age estimation in living adolescents and young adults. The following hypotheses were made: 1. MRI outperforms CR. 2. An atlas method outperforms a staging technique to assess hand/wrist development. Materials and methods: CR and 3T MRI were prospectively conducted in 108 healthy Caucasian volunteers (52 males, 56 females) with ages ranging from 16 to 21 years. Five observers allocated stages and standards to (part of) the images independently. Staging techniques were applied to the left radius and ulna, and to both clavicles as described in (3, 4). Furthermore, atlas methods were applied to the left hand/wrist as described in (5, 6). For clavicle CR, one posteroanterior and two oblique radiographs were assessed simultaneously. Inter- and intraobserver agreements were quantified, and descriptive statistics were reported. Results: Inter- and intra-observer agreements for wrist CR and MRI were similar. By contrast, the CR atlas method was less reproducible than the staging technique. Inter- and intra-observer agreements for clavicle CR were lower than those for MRI. Regarding the wrist, within-stage age distributions were similar on CR and MRI, as were those for the staging techniques and atlas methods. Regarding the clavicles, the possibility to apply (profound) substages to MRI rendered a more gradual increase in the age distributions with increasing stages, than on CR. Conclusion: For multi-factorial age estimation based on the left wrist and both clavicles, CR suffices for the wrist, while MRI is necessary for the clavicles. Furthermore, a wrist staging technique is more useful than an atlas method