Spine segmentation and enumeration and normal variants

The Anatomy, Technique, Safety, and Efficacy of Image-Guided Epidural Access

Epidural steroid injections have demonstrable efficacy and safety in treatment of radicular pain syndromes; transforaminal access has greater evidence of efficacy than interlaminar approaches. The interventionalist must understand epidural and foraminal anatomy and imaging to insure delivery of medication to the target, the ventral epidural space at the site of neural compression. This obligates pre-procedural planning. When performed with appropriate risk mitigation strategies, epidural injections by either access are safe. For transforaminal access, the use of dexamethasone as the injectate, and infraneural approaches, provides safety advantages.

Frequency of Coexistent Spinal Segment Variants: Retrospective Analysis in Asymptomatic Young Adults

BACKGROUND AND PURPOSE

Spinal segment variants are highly prevalent and can potentially lead to incorrect spinal enumeration and, consequently, interventions or surgeries at the wrong vertebral levels. Our aim was to assess the prevalence of spinal segment variants and to study the potential association among these variants in a population without histories of spine symptoms.

MATERIALS AND METHODS

Consecutive computed tomography exams of 450 young adults originally evaluated for non-spinal conditions and without a history of spinal diseases from a single institution. In addition to using descriptive statistics for reporting frequencies of spinal segment variants, the association between these variants was studied by calculating odds ratios and their 95% confidence interval. Consecutive CT exams were evaluated to determine the total number of presacral segments, presence of cervical rib, thoracolumbar transitional vertebra, iliolumbar ligament, and lumbosacral transitional vertebra.

RESULTS

The spinal segment distribution variants (an atypical number of presacral segments or an atypical distribution of thoracolumbar vertebrae), cervical rib, thoracolumbar transitional vertebra, and lumbosacral transitional vertebra were reported in 23.8%, 4.2%, 15.3%, and 26.4% of cases in our study population. The presence of a cervical rib or a thoracolumbar transitional vertebra was associated with concurrent lumbosacral transitional vertebra (OR = 3.28; 95% CI, 1.29-8.47 and 1.87; 95% CI, 1.08-3.20, respectively). The inability to visualize the iliolumbar ligament was also associated with the presence of cervical ribs (OR = 3.06; 95% CI, 1.18-7.80).

CONCLUSIONS

In a population of asymptomatic young adults, spinal segment variants are both highly prevalent with a high rate of coexistence. When a spinal segment variant (eg, transitional vertebra) is diagnosed, additional imaging might be considered for accurate spine enumeration before interventions or operations.

Pediatric Spine Tumors and Dysontogenetic Masses

The pediatric spine undergoes complex stages of development and growth, resulting in highly age-dependent physiology and variable susceptibility to certain pathologies. Optimal radiologic evaluation requires image acquisition tailored to the clinical history and an interpretive approach that accounts for demographic variations. In this article, the author discusses the diagnostic approach to pediatric spine masses, beginning with a discussion of normal anatomy and variants, clinical evaluation, and imaging techniques and protocols. The author then covers the major etiologies, imaging appearances, and mimics of pediatric spine masses in the following categories: congenital malformations, genetic syndromes, intramedullary, intradural, epidural, bone, and paraspinal lesions.

Prevalence of lumbosacral transitional vertebra among 4816 consecutive patients with low back pain: A computed tomography, magnetic resonance imaging, and plain radiographic study with novel classification schema

Study Design

A retrospective single-center study.

Background

The prevalence of the lumbosacral anomalies remains controversial. The existing classification to characterize these anomalies is more complex than necessary for clinical use.

Purpose

To assessment of the prevalence of lumbosacral transitional vertebra (LSTV) in patients with low back pain and the development of clinically relevant classification to describe these anomalies.

Materials and Methods

During the period from 2007 to 2017, all cases of LSTV were preoperatively verified, and classified according to Castellvi, as well as O'Driscoll. We then developed modifications of those classifications that are simpler, easier to remember, and clinically relevant. At the surgical level, this was assessed intervertebral disc and facet joint degeneration.

Results

The prevalence of the LSTV was 8.1% (389/4816). The most common L5 transverse process anomaly type was fused, unilaterally or bilaterally (48%), to the sacrum and were O'Driscoll's III (40.1%) and IV (35.8%). The most common type of S1-2 disc was a lumbarized disc (75.9%), where the disc's anterior-posterior diameter was equal to the L5-S1 disc diameter. In most cases, neurological compression symptoms (85.5%) were verified to be due to spinal stenosis (41.5%) or herniated disc (39.5%). In the majority of patients without neural compression, the clinical symptoms were due to mechanical back pain (58.8%).

Conclusions

LSTV is a fairly common pathology of the lumbosacral junction, occurring in 8.1% of the patients in our series (389 out of 4,816 cases). The most common types were Castellvi's type IIA (30.9%) and IIIA (34.9%) and were O'Driscoll's III (40.1%) and IV (35.8%).

Congenital malformations in the vertebral column: associations and possible embryologic origins

Cases of associations between random spinal congenital defects have previously been reported, yet several questions remain unanswered. Firstly, why are associations between what seems to be random combinations of vertebral malformations observed? Secondly, is there a common event or pattern that connects the associated defects? Therefore, this study aimed to identify congenital defects in the vertebral column and also to determine whether any associations, if present, between vertebral malformations exist. This article consequently discusses the possible embryological disruptions that may lead to the formation of various defects in the vertebral column. A random skeletal sample (n=187) was selected from the Pretoria Bone Collection housed in the Department of Anatomy, University of Pretoria (Ethics 678/2018). The sample was evaluated to determine the frequencies of spinal congenital defects in each set of remains. Identifiable congenital malformations were observed in 48.1% (n=90/187) of the sample. The results demonstrated a high probability of association between the different defects observed in the vertebral column. Findings are of value as they provide a reasonable explanation to why seemingly random cases of associations have been reported by several authors. This study is clinically relevant as severe spinal defects have been shown to have high morbidity in patients and mortality in infants.

Identification of LTBP2 gene polymorphisms and their association with thoracolumbar vertebrae number, body size, and carcass traits in Dezhou donkeys

The number of thoracolumbar vertebrae in Dezhou donkeys varies from 22 to 24 and is associated with body size and carcass traits. In mammals, the latent transforming growth factor beta binding protein 2 (LTBP2) has been found to have some functions in the development of thoracolumbar vertebrae. The relationship between LTBP2 and TLN (the number of thoracolumbar vertebrae) of Dezhou donkeys is yet to be reported. The purposes of this study are as follows: 1) to quantify the effect of thoracolumbar vertebrae number variation of Dezhou donkeys on body size and carcass trait; 2) to study the distribution of single nucleotide variants (SNVs) in the LTBP2 gene of Dezhou donkeys; and 3) to explore whether these SNVs can be used as candidate sites to study the mechanism of Dezhou donkey muti-thoracolumbar vertebrae development. The TLN, body size, and carcass traits of 392 individuals from a Dezhou donkey breed were recorded. All animals were sequenced for LTBP2 using GBTS liquid chip and 16 SNVs were used for further analysis. We then analyzed the relationship between these SNVs with TLN, body size, and carcass traits. The results showed that: 1) c.5547 + 860 C > T, c.5251 + 281 A > C, c.3769 + 40 C > T, and c.2782 + 3975 A > G were complete genetic linkages and significantly associated with thoracic vertebrae number (TN) (p < 0.05) (wild-type homozygotes had more TN than heterozygotes); 2) c.1381 + 768 T > G and c.1381 + 763 G > T were significantly associated with lumber vertebrae number (LN) (p < 0.05); 3) c.1003 + 704 C > T, c.1003 + 651 C > T, c.1003 + 626 A > G, and c.812 + 22526 T > G were significantly associated with chest circumference (CHC), front carcass weight (CWF), after carcass weight (CWA), and carcass weight (CW) (p < 0.05) (wild-type homozygotes were larger than other genotypes in CHC, CWF, CWA, and CW); and 4) the effect of variation is not consistent in c.565 + 11921 A > G, c.565 + 6840 A > G, c.565 + 3453 C > T, and c.494 + 5808 C > T. These results provide useful information that the polymorphism of LTBP2 is significantly associated with TLN, body size, and carcass traits in Dezhou donkeys, which can serve as a molecule marker to improve donkey production performance.

Vertebrae at the thoracolumbar junction: A quantitative assessment using CT scans

The thoracolumbar junction is often associated with traumatic injuries, due to its biomechanical instability. Reasons for this instability are currently still under debate; however, contributing factors such as the rapid change in spinal curvature and facet orientation from the thoracic to lumbar transition have been implicated. Normally, the superior facet orientation in the thoracic region is angled in a coronal plane, whereas vertebrae in the lumbar region have facets angled in the sagittal plane. Distinguishing between thoracic, lumbar, and transitional vertebrae at the thoracolumbar junction based on articular facet angles, using quantitative methods on CT scans has, to the authors' knowledge, not yet been reported in the literature. Therefore, this study aimed to evaluate whether quantitative measurements can be clinically applied and used to differentiate vertebrae at the thoracolumbar junction using CT scans and, additionally, to record possible cases of congenital defects or variations observed in the spine. A sample (n = 173) of CT scans representative of the Windhoek population in Namibia was retrospectively assessed using radio-imaging software. Measurements of the angle formed by the superior facets of the vertebrae at the thoracolumbar junction (T11-L1) were recorded. Based on the results of this study, quantitative morphometry of the superior facet of vertebrae can differentiate between thoracic, lumbar,. and transitional vertebrae at the thoracolumbar junction. All individuals with identified thoracolumbar transitional vertebrae (TLTV) in this sample had at least one other congenital anomaly of the spine.

Quantitative measurements at the lumbosacral junction are more reliable parameters for identifying and numbering lumbosacral transitional vertebrae

OBJECTIVES

To evaluate quantitative parameters to identify the anatomic variation lumbosacral transitional vertebrae (LSTV) and compare them with the landmarks commonly used at present.

METHODS

A total of 2,845 PET/CT scans were reviewed, and the patients with 23 and 25 presacral vertebrae were included. The quantitative parameters, including the anterior-edge vertebral angle (AVA) of the lowest lumbar-type vertebra, the ratio of the length of the inferior endplate to that of the superior endplate (RISE) of the uppermost sacral-type vertebra and the lumbosacral intervertebral disc angle (LSIVDA), and the anatomical landmarks, including the iliac crest tangent (ICT) level, the iliolumbar ligament (ILL) origin level and psoas proximal insertion, were all evaluated to determine their ability to identify LSTV.

RESULTS

The values of AVA and RISE were significantly different between the LSTV group and the control group, and between subgroups of LSTV. The cutoff value for AVA was 73.0°, with an accuracy, sensitivity, and specificity of 91.1%, 77.5%, and 88.3%, and that for RISE was 0.79, with an accuracy, sensitivity, and specificity of 90.3%, 77.5%, and 94.2%, while that for LSIVDA was 14.15°, with an accuracy, sensitivity, and specificity of 75.9%, 65.7%, and 78.3%, to differentiate L5 sacralization from S1 lumbarization. For differentiating the controls from LSTV, the accuracy, sensitivity, and specificity of the ICT level and proximal psoas insertion were 78.0%, 70.2%, and 95.0%, versus 71.7%, 61.7%, and 94.0%.

CONCLUSIONS

Compared with the anatomical landmarks, the quantitative measurements at the lumbosacral junction, including AVA and RISE, may be more helpful for differentiating subgroups of LSTV especially if only lumbar spine imaging is available.

KEY POINTS

• The quantitative parameters, the anterior-edge vertebral angle (AVA) of the lowest lumbar-type vertebra and the ratio of the length of the inferior endplate to that of the superior endplate (RISE) of the uppermost sacral-type vertebra, are more helpful for distinguishing L5 sacralization from S1 lumbarization than the previously proposed anatomic landmarks. • AVA and RISE represent relevant changes in the curvature at the lumbosacral region and the shape of the transitional vertebral body, respectively. • AVA and RISE are easily assessed, with high intra- and inter-reader reliability.

Spinal health in 40 patients in the initial stage of laboural life. Morfogeometric, biological and environmental study

Introduction

Assuming that spinal shape is a genetic expression, its analysis and acquired factors could assess their respective contribution to early spine deterioration.

Material and methods

A geometric morphometric analysis was retrospectively performed on sagittal lumbar MRI of young patients with back pain to identify lumbar spine shape changes. Using Geometric Morphometrics, findings were analyzed with anthropometric, radiological, and clinical variables.

Results

80 cases under 26 years of age were collected, 55 men (mean age 22.81) and 25 women (mean age 23.24). MRI abnormalities were reported in 57.5%: single altered disc (N=17), root compromises (N=8), and transition anomalies (35%).In the non-normal MRI subgroup, shape variation included: increased lordosis, enlarged vertebral body, canal stenosis, and lumbarization of S1. In non-Spanish origin patients, lumbar straightening and segmental deformities were prevalent. Morphometrics findings showed that lumbosacral transition anomalies are frequently underreported.

Conclusions

Genetic factors could be the main determinants of abnormality in MRIs under 26 years. The primary markers are transitional abnormalities, segmental deformities, and canal stenosis. In foreign populations, shape changes could suggest spine overload at an early age.

A Primer on the Use of Artificial Intelligence in Spine Surgery

DESIGN

This was a narrative review.

PURPOSE

Summarize artificial intelligence (AI) fundamentals as well as current and potential future uses in spine surgery.

SUMMARY OF BACKGROUND DATA

Although considered futuristic, the field of AI has already had a profound impact on many industries, including health care. Its ability to recognize patterns and self-correct to improve over time mimics human cognitive function, but on a much larger scale.

METHODS

Review of literature on AI fundamentals and uses in spine pathology.

RESULTS

Machine learning (ML), a subset of AI, increases in hierarchy of complexity from classic ML to unsupervised ML to deep leaning, where Language Processing and Computer Vision are possible. AI-based tools have been developed to segment spinal structures, acquire basic spinal measurements, and even identify pathology such as tumor or degeneration. AI algorithms could have use in guiding clinical management through treatment selection, patient-specific prognostication, and even has the potential to power neuroprosthetic devices after spinal cord injury.

CONCLUSION

While the use of AI has pitfalls and should be adopted with caution, future use is promising in the field of spine surgery and medicine as a whole.

LEVEL OF EVIDENCE

Level IV.

Anatomical Variations That Can Lead to Spine Surgery at The Wrong Level: Part II Thoracic Spine

Spine surgery at the wrong level is a detrimental ordeal for both surgeon and patient, and it falls under the wrong-site surgery sentinel events reporting system. While there are several methods designed to limit the incidence of these events, they continue to occur and can result in significant morbidity for the patient and malpractice lawsuits for the surgeon. In thoracic spine, numerous risk factors influence the development of this misadventure. These include anatomical variations such as transitional vertebrae, rib variants, hemivertebra, and block/fused vertebrae as well as patient characteristics, such as tumors, infections, previous thoracic spine surgery, obesity, and osteoporosis. An extensive literature search of the PubMed database up to 2019 was completed on each of the anatomical entities and their influence on developing thoracic spine surgery at the wrong level, taking into consideration patient’s individual factors. A reliable protocol and effective techniques were described to prevent this error. In addition, the surgeon should collaborate with radiologists, particularly in challenging cases. A thorough understanding of the surgical anatomy and its variants coupled with patients characteristic is crucial for maximal patient benefit and avoidance of thoracic spine surgery at the wrong level.

The prevalence and clinical significance of transitional vertebrae: a radiologic investigation using whole spine spiral three-dimensional computed tomographic images

Background

Errors in counting spinal segments are common during interventional procedures when there are transitional vertebrae. In this study, we investigated the prevalence of the transitional vertebrae including thoracolumbar transitional vertebra (TLTV) and lumbosacral transitional vertebrae (LSTV). The relationship between the existence of TLTV and abnormal rib count or the existence of LSTV were also evaluated.

Methods

The vertebral levels were counted craniocaudally, starting from C1, based on the assumption of 7 cervical, 12 thoracic, and 5 lumbar vertebrae, using whole spine spiral three-dimensional computed tomographic images. The 20th and 25th vertebrae were defined as L1 and S1, respectively.

Results

In total, 150 patients had TLTV, with a prevalence of 11.2% (150/1,340). LSTV was observed in 111 of 1,340 cases (8.3%). Sacralization was observed in 68 of 1,340 cases (5.1%) and lumbarization in 43 of 1,340 cases (3.2%). There was a significant relationship between the existence of TLTV and the abnormal rib count (odds ratio [OR]: 117.26, 95% confidence interval [95% CI]: 60.77-226.27; P < 0.001) and LSTV (OR: 7.38, 95% CI: 3.99-13.63; P < 0.001).

Conclusions

Our study results suggest that patients with TLTV are more likely to have an abnormal rib count or LSTV. If a TLTV or LSTV is seen on the fluoroscopic image, a whole spine image is necessary to permit accurate numbering of the lumbar vertebra.

Unveiling the tale of the tail: an illustration of spinal dysraphisms

Spinal dysraphism is an umbrella term describing herniation of meninges or neural elements through defective neural arch. They can be broadly categorized into open and closed types. MRI is the investigation of choice to study neural abnormalities and to assess the severity of hydrocephalus and Chiari malformation. Knowledge of the embryology of these disorders is valuable in correctly identifying the type of dysraphism. The aim of surgery is untethering and dural reconstruction. Accurate depiction of the abnormal anatomy in cases of spinal dysraphism is of utmost importance for surgical management of these patients. MRI makes this possible due to its excellent soft tissue contrast resolution and multiplanar capability, allowing the radiologist to evaluate the intricate details in small pediatric spinal structures. Imaging enlightens the surgeons about the status of spinal cord and other associated abnormalities and helps detect re-tethering in operated cases. Besides, antenatal surgery to repair myelomeningoceles has made detection of open dysraphisms on fetal MRI and antenatal ultrasound critical. The purpose of this review is to describe the development of spine, illustrate the myriad imaging features of open and closed spinal dysraphisms, and enlist the reporting points the operating surgeon seeks from the radiologist.

Induced lumbosacral radicular symptom referral patterns: a descriptive study

BACKGROUND CONTEXT

Lumbosacral radicular symptoms are commonly evaluated in clinical practice. Level-specific diagnosis is crucial for management. Clinical decisions are often made by correlating a patient's symptom distribution and imaging with sensory dermatomal maps. It is common for patients to describe non-dermatomal symptom patterns and for imaging to demonstrate pathology at levels not predicted by a dermatomal map. These observations suggest that the referred symptom distribution from lumbosacral nerve root provocation is different from dermatomal maps. This phenomenon has been demonstrated in the cervical spine but not in the lumbosacral spine.

PURPOSE

The objective of this study was to characterize potential lumbosacral radicular symptom referral patterns induced during transforaminal epidural injections.

STUDY DESIGN/SETTING

This is an observational descriptive study.

PATIENT SAMPLE

The patient sample included 71 consecutive patients with lumbosacral radicular pain undergoing lumbosacral transforaminal epidural injections at an outpatient interventional spine practice.

OUTCOME MEASURES

Each subject drew the location of provoked lumbosacral radicular symptoms on a pain diagram.

MATERIALS AND METHODS

Seventy-one consecutive patients undergoing 125 fluoroscopically guided lumbosacral transforaminal epidural injections at an outpatient interventional spine practice were included in the study. The described location of provoked symptoms was recorded (1) after final needle positioning, (2) after injection of up to 0.5 mL of contrast solution, and (3) after injection of up to a 1 mL test dose of 1% lidocaine. Each subject drew the location of provoked symptoms on a diagram. The provoked symptom diagrams for each lumbosacral segmental level were combined to create composite nerve root, level-specific, symptom referral pattern maps.

RESULTS

Of the 125 injections, 87 provoked referred symptoms and were included in the analysis. Thirty-eight injections did not provoke referred pain symptoms and were excluded from further analysis. Four nerve roots were tested at L1 and eight were tested at L2. Because of the small number of subjects, composite diagrams and statistical analysis were not completed for these levels. Eleven nerve roots were analyzed at L3, 28 at L4, 34 at L5, and 11 at S1. Composite symptom referral pattern maps were created for levels L3, L4, L5, and S1. Although the symptom distribution occasionally followed the expected dermatomal maps, most often the referral was outside of the patterns expected for each level. The most common symptom referral pattern for levels L3-S1 was the buttock, the posterior thigh, and the posterior calf.

CONCLUSIONS

The level-specific provoked symptom distribution during lumbosacral transforaminal epidural injections is frequently different from that predicted by classic lumbosacral dermatomal maps. Referred pain to the buttock, the posterior thigh, or the posterior calf may come from L3, L4, L5, or S1 nerve root segmental irritation.

Spinal Enumeration by Morphologic Analysis of Spinal Variants: Comparison to Counting in a Cranial-To-Caudal Manner

Objective

To compare the spinal enumeration methods that establish the first lumbar vertebra in patients with spinal variants.

Materials and Methods

Of the 1446 consecutive patients who had undergone computed tomography of the spine from March 2012 to July 2016, 100 patients (62 men, 38 women; mean age, 47.9 years; age range, 19-88 years) with spinal variants were included. Two radiologists (readers 1 and 2) established the first lumbar vertebra through morphologic analysis of the thoracolumbar junction, and labeled the vertebra by counting in a cranial-to-caudal manner. Inter-observer agreement was established. Additionally, reader 1 detected the 20th vertebra under the assumption that there are 12 thoracic vertebra, and then classified it as a thoracic vertebra, lumbar vertebra, or thoracolumbar transitional vertebra (TLTV), on the basis of morphologic analysis.

Results

The first lumbar vertebra, as established by morphologic analysis, was labeled by each reader as the 21st segment in 65.0% of the patients, as the 20th segment in 31.0%, and as the 19th segment in 4.0%. Inter-observer agreement between the two readers in determining the first lumbar vertebra, based on morphologic analysis, was nearly perfect (κ value: 1.00). The 20th vertebra was morphologically classified as a TLTV in 60.0% of the patients, as the first lumbar segment in 31.0%, as the second lumbar segment in 4.0%, and as a thoracic segment in 5.0%.

Conclusion

The establishment of the first lumbar vertebra using morphologic characteristics of the thoracolumbar junction in patients with spinal variants was consistent with the morphologic traits of vertebral segmentation.

Differentiation and classification of thoracolumbar transitional vertebrae

The literature states that transitional vertebrae at any junction are characterized by features retained from two adjacent regions in the vertebral column. Currently, there is no published literature available that describes the prevalence or morphology of thoracolumbar transitional vertebrae (TLTV). The aim of this study was to identify the qualitative characteristics of transitional vertebrae at the thoracolumbar junction and establish a technique to differentiate the various subtypes that may be found. A selection of vertebral columns from skeletal remains (n = 35) were evaluated in this study. Vertebrae were taken based on features that are atypical for vertebrae in each relative region. The transitional vertebrae were qualitatively identified based on overlapping thoracic and lumbar features of vertebrae at the thoracolumbar junction. The following general overlapping characteristics were observed: aplasia or hypoplasia of the transverse process, irregular orientation on the superior articular process and atypical mammillary bodies. The results show that the most frequent location of the transitional vertebrae was in the thoracic region (f = 23). The second most frequent location was in the lumbar region (f = 10). In two specimens of the selection (f = 2), an additional 13th thoracic vertebra was present which functioned as a transitional vertebra. This study concluded that one can accurately identify the characteristics of transitional vertebrae at the thoracolumbar junction. In addition, the various subtypes can be differentiated according to the region in the vertebral column the vertebra is located in and the relative number of vertebral segments in the adjacent regions of the vertebral column. This provides a qualitative tool for researchers to differentiate the transitional vertebrae from distinctly different typical thoracic or lumbar vertebrae at the thoracolumbar junction.

Localizing the L5 Vertebra Using Nerve Morphology on MRI: An Accurate and Reliable Technique

BACKGROUND AND PURPOSE

Multiple methods have been used to determine the lumbar vertebral level on MR imaging, particularly when full spine imaging is unavailable. Because postmortem studies show 95% accuracy of numbering the lumbar vertebral bodies by counting the lumbar nerve roots, attention to lumbar nerve morphology on axial MR imaging can provide numbering clues. We sought to determine whether the L5 vertebra could be accurately localized by using nerve morphology on MR imaging.

MATERIALS AND METHODS

One hundred eight cases with full spine MR imaging were numbered from the C2 vertebral body to the sacrum with note of thoracolumbar and lumbosacral transitional states. The origin level of the L5 nerve and iliolumbar ligament were documented in all cases. The reference standard of numbering by full spine imaging was compared with the nerve morphology numbering method. Five blinded raters evaluated all lumbar MRIs with nerve morphology technique twice. Prevalence and bias-adjusted κ were used to measure interrater and intrarater reliability.

RESULTS

The L5 nerve arose from the 24th presacral vertebra (L5) in 106/108 cases. The percentage of perfect agreement with the reference standard was 98.1% (95% CI, 93.5%-99.8%), which was preserved in transitional and numeric variation states. The iliolumbar ligament localization method showed 83.3% (95% CI, 74.9%-89.8%) perfect agreement with the reference standard. Inter- and intrarater reliability when using the nerve morphology method was strong.

CONCLUSIONS

The exiting L5 nerve can allow accurate localization of the corresponding vertebrae, which is essential for preprocedure planning in cases where full spine imaging is not available. This neuroanatomic method displays higher agreement with the reference standard compared with previously described methods, with strong inter- and intrarater reliability.

Prenatal diagnosis and assessment of congenital spinal anomalies: Review for prenatal counseling

The last two decades have seen continuous advances in prenatal ultrasonography and in utero magnetic resonance imaging. These technologies have increasingly enabled the identification of various spinal pathologies during early stages of gestation. The purpose of this paper is to review the range of fetal spine anomalies and their management, with the goal of improving the clinician’s ability to counsel expectant parents prenatally.

Incidence of numerical variants and transitional lumbosacral vertebrae on whole-spine MRI

Objectives

This study sets out to prospectively investigate the incidence of transitional vertebrae and numerical variants of the spine.

Materials and methods

Over a period of 28 months, MRIs of the whole spine were prospectively evaluated for the presence of transitional lumbosacral vertebrae and numerical variants of the spine.

Results

MRI of the whole spine was evaluated in 420 patients, comprising 211 female and 209 male subjects. Two patients had more complex anomalies. Lumbosacral transitional vertebrae were seen in 12 patients: eight sacralised L5 (3 male, 5 female) and four lumbarised S1 (3 male, 1 female). The incidence of transitional vertebrae was approximately 3.3. % (14/418). Thirty-two (7.7 %) of 418 patients had numerical variants of mobile vertebrae of the spine without transitional vertebrae. The number of mobile vertebrae was increased by one in 18 patients (12 male, 6 female), and the number was decreased by one in 14 patients (4 male, 10 female).

Conclusions

Numerical variants of the spine are common, and were found to be almost 2.5 times as frequent as transitional lumbosacral vertebrae in the study population. Only whole-spine imaging can identify numerical variants and the anatomical nature of transitional vertebrae. The tendency is toward an increased number of mobile vertebrae in men and a decreased number in women.

Main messages

• Numerical variants of the spine are more common than transitional vertebrae.

• Spinal numerical variants can be reliably identified only with whole-spine imaging.

• Increased numbers of vertebrae are more common in men than women.

• Transitional lumbosacral vertebrae occurred in about 3.3 % of the study population.

• The incidence of numerical variants of the spine was about 7.7 %.

Thoracolumbar junction: morphologic characteristics, various variants and significance

OBJECTIVE:

This study aimed to assess the types of vertebral segments at the thoracolumbar junction, as they relate to the most caudal ribs, to evaluate the reliability of this assessment using axial CT with curved planar reformatting (CPR) images, to describe the morphologic characteristics of a thoracolumbar transitional vertebra (TLTV), to introduce a new classification system for the TLTV and to evaluate the reliability of the classification system using axial CT with CPR images.

METHODS:

This was a retrospective review of 744 consecutive patients who underwent spine CT imaging that included the thoracolumbar junction. Two radiologists (Readers 1 and 2) independently evaluated the axial CT with CPR images for all cases (n = 744). Each radiologist differentiated the vertebral segments at the thoracolumbar junction as TLTV or non-TLTV (thoracic segment or lumbar segment). In addition, each radiologist classified the 94 patients with the TLTV using a novel classification system. Interobserver agreement between the two radiologists regarding the differentiation of vertebral segments at the thoracolumbar junction was analysed with kappa statistics. Similarly, intra- and interobserver agreement regarding TLTV classification was analysed with kappa statistics.

RESULTS:

Interobserver agreement between the two readers with respect to the differentiation of vertebral segments at the thoracolumbar junction via axial CT with CPR images was nearly perfect (κ-value: 0.959). Interobserver agreement between the two readers with respect to TLTV classification using axial CT with CPR images was nearly perfect (κ-value: 0.846). In addition, intraobserver agreement for Reader 1 was also nearly perfect (κ-value: 0.877).

CONCLUSION:

Morphologic analysis of the thoracolumbar junction may help accurate spinal enumeration.

ADVANCES IN KNOWLEDGE:

Consideration of various variants at the thoracolumbar junction should help radiologists and clinicians to interpret the morphology of the thoracolumbar junction. This may facilitate communication with the referring clinician, thereby reducing the error in spinal enumeration.

Freehand three-dimensional ultrasound system for assessment of scoliosis

Background/Objective

Standing radiograph with Cobb's method is routinely used to diagnose scoliosis, a medical condition defined as a lateral spine curvature > 10° with concordant vertebral rotation. However, radiation hazard and two-dimensional (2-D) viewing of 3-D anatomy restrict the application of radiograph in scoliosis examination.

Methods

In this study, a freehand 3-D ultrasound system was developed for the radiation-free assessment of scoliosis. Bony landmarks of the spine were manually extracted from a series of ultrasound images with their spatial information recorded to form a 3-D spine model for measuring its curvature. To validate its feasibility, in vivo measurements were conducted in 28 volunteers (age: 28.0 ± 13.0 years, 9 males and 19 females). A significant linear correlation (R² = 0.86; p < 0.001) was found between the spine curvatures as measured by Cobb's method and the 3-D ultrasound imaging with transverse process and superior articular process as landmarks. The intra- and interobserver tests indicated that the proposed method is repeatable.

Results

The 3-D ultrasound method using bony landmarks tended to underestimate the deformity, and a proper scaling is required. Nevertheless, this study demonstrated the feasibility of the freehand 3-D ultrasound system to assess scoliosis in the standing posture with the proposed methods and 3-D spine profile.

Conclusion

Further studies are required to understand the variations that exist between the ultrasound and radiograph results with a larger number of volunteers, and to demonstrate its potential clinical applications for monitoring of scoliosis patients. Through further clinical trials and development, the reported 3-D ultrasound imaging system can potentially be used for scoliosis mass screening and frequent monitoring of progress and treatment outcome because of its radiation-free and easy accessibility feature.

Is any landmark reliable in vertebral enumeration? A study of 3.0-Tesla lumbar MRI comparing skeletal, neural, and vascular markers

PURPOSE

This study aimed to determine the reliability of the iliolumbar ligament (ILL), 12th costa, aortic bifurcation (AB), right renal artery (RRA), and conus medullaris (CM) for numbering of vertebral segments.

SUBJECTS AND METHODS

Five hundred five patients underwent routine lumbar MRI examinations including a cervicothoracic sagittal scout and T1 and T2-weighted sagittal and axial turbo spin echo images. Images were evaluated by two radiologists separately.

RESULTS

The identifiability of ILL and 12th costa were 85.7% and 48.1%. AB, RRA, and CM were located more caudally in lumbarized S1 and more cranially in sacralized L5 cases.

CONCLUSION

Landmarks suggested by previous studies are not reliable alternatives to cervicothoracic scout images due to wide ranges of distribution and inconsistencies in identification.