Numbering of vertebrae on MRI using a PACS cross-referencing tool

Identification of L5 vertebra on lumbar spine radiographs using deep learning

OBJECTIVE

Deep learning is an advanced machine-learning approach that is used in several medical fields. Here, we developed a deep learning model using an object detection algorithm to identify the L5 vertebra on anteroposterior lumbar spine radiographs, and assessed its detection accuracy.

METHODS

We retrospectively recruited 150 participants for whom both anteroposterior whole-spine and lumbar spine radiographs were available. The anteroposterior lumbar spine radiographs of these patients were used as the input data. Of the 150 images, 105 (70%) were randomly selected as the training set, and the remaining 45 (30%) were assigned to the validation set. YOLOv5x, of the YOLOv5 family model, was used to detect the L5 vertebra area.

RESULTS

The mean average precisions 0.5 and 0.75 of the trained L5 detection model were 99.2% and 96.9%, respectively. The model's precision was 95.7% and its recall was 97.8%. Furthermore, 93.3% of the validation data were correctly detected.

CONCLUSION

Our deep learning model showed an outstanding ability to identify L5 vertebrae.

Emergence of teleradiology, PACS, and other radiology IT solutions in Acta Radiologica

For this historical review, we searched a database containing all the articles published in Acta Radiologica during its 100-year history to find those on the use of information technology (IT) in radiology. After reading the full texts, we selected the presented articles according to major radiology IT domains such as teleradiology, picture archiving and communication systems, image processing, image analysis, and computer-aided diagnostics in order to describe the development as it appeared in the journal. Publications generally follow IT megatrends, but because the contents of Acta Radiologica are mainly clinically oriented, some technology achievements appear later than they do in journals discussing mainly imaging informatics topics.

The phenotypic morphology of human lumbar plexus roots associated with changes in the thoracolumbar vertebral count and trade-off

This study investigated the developmental basis for the human phenotypic morphology of the interaction between the vertebrae and the nerve plexus by evaluating changes in the human lumbar plexus according to various thoracolumbar formulas. The dissection found that the changes in lumbar nerve roots reported by experimental embryology studies to be concomitant with thoracolumbar trade-off, i.e., a change in vertebrae from thoracic to lumbar with no change in the overall thoracolumbar count, were not apparent in humans with the usual 17 or mutant 16 thoracolumbar vertebrae. When vertebral changes in two segments were examined by comparing spines with a reduced thoracolumbar count of 16 to those with an increased count of 18, this tended to show only a single-segment caudal shift of the lumbar plexus. We cannot provide evidence for the phylogenetic difference in the concomitant changes of lumbar nerves and vertebrae, but comparisons between experimental rodents and humans highlighted fewer and shorter lumbar vertebra and more complicated lumbar plexus in humans. Therefore, these multiple differences may contribute to a human phenotypic morphology that is not evident in the concomitant transformation of vertebrae and lumbar nerves reported in experimental rodents.

Spinopelvic Parameters and Sagittal Alignment of Symptomatic Degenerative Adult Spinal Disorder Patients With 6 Lumbar Vertebrae

STUDY DESIGN

This was a cross-sectional, observational study.

OBJECTIVE

The main objectives of this study were to observe the prevalence of a true L6 among patients with symptomatic adult spinal degeneration, and to evaluate similarities of their radiographic spinopelvic parameters to L5 patients.

SUMMARY OF BACKGROUND DATA

Spinopelvic parameter values used for diagnosis and surgical planning are different between individuals with 5 or 6 lumbar vertebrae. The difference has not been studied in patients with symptomatic spinal degenerative conditions.

MATERIALS AND METHODS

A total of 775 consecutive symptomatic patients with degenerative spinal disorders were classified as having 5 or 6 lumbar vertebrae in full spine radiographs. Pelvic incidence minus lumbar lordosis (PI-LL), sagittal vertical axis (SVA), pelvic tilt, and T1 pelvic angle were measured in 3 groups: sacral (L5 and L6s) and L6 upper endplate (L6e). Oswestry Disability Index (ODI) was obtained.

RESULTS

In total, 715 (92.3%) patients had L5 and 60 (7.7%) had L6. LL values were comparable between the L5 and L6s (P=0.355) and SVA between all groups (P=0.869). Only SVA had excellent concordance correlation (ρc=0.91) between the L6s and L6e groups. PI-LL had significantly different values (P<0.001 all groups) and distributions between L5 and L6s (P=0.038), and L6s and L6e (P<0.001) groups. In patients with severe disability (ODI>40%) the parameters that deteriorate with increasing degeneration (pelvic tilt, T1 pelvic angle, SVA, LL, PI-LL) were not significantly different between L5 and L6s groups unlike patients with ODI<40% while PI remained similarly different (P<0.001). PI and LL had a multivariate relationship in L6 patients computable as regression model equation: PI (sacrum)=-0.92×LL (L6e)+0.91×LL (sacrum) +1.11×PI (L6e)+10.81 (R=0.88).

CONCULSIONS

L6 variant is fairly common. The radiographic L6 parameters were different from L5 except for SVA and values of patients with severe disability measured from sacrum. PI and LL have a mathematic relationship in L6 patients. The cutoff values for radiographic modifiers need further studies combining radiology and clinical outcome.

LEVEL OF EVIDENCE

Level III.

Psoas proximal insertion as a simple and reliable landmark for numbering lumbar vertebrae on MRI of the lumbar spine

OBJECTIVE

To evaluate the value of psoas muscle proximal insertion for correct numbering of the lumbar vertebrae in MRI, in particular in case of lumbosacral transitional vertebra (LSTV).

METHODS

Two radiologists assessed 477 MRI scans of the lumbar spine with a sagittal localizer sequence on the whole spine for numbering vertebrae caudally from C2. Proximal insertion of the psoas was determined as the most proximal vertebra with psoas over half of its body on coronal T2 STIR sequence. The last lumbar vertebra was named considering both its number and the presence or absence of LSTV according to Castellvi classification. These same parameters were also assessed on 207 PET-CT scans of another cohort including the whole spine.

RESULTS

Proximal insertion of the psoas was L1 in 94.1% of cases: 98.5% in case of modal anatomy, 81.4% in case of LSTV, and 51.7% in case of missing or supernumerary lumbar vertebra without LSTV. There was no statistically significant difference between MRI and CT data. The inter-reader agreement for determination of psoas proximal insertion was excellent (kappa = 0.96).

CONCLUSION

Proximal insertion of the psoas muscle is a helpful marker for correct numbering of the lumbar vertebrae in MRI and to detect a complete lumbosacral segmentation anomaly.

KEY POINTS

• Proximal insertion of the psoas muscle can be easily identified on a coronal T2 STIR sequence. • Psoas proximal insertion on the spine almost always designates the first lumbar vertebra and is helpful to accurately number all lumbar vertebrae, especially in case of lumbosacral transitional vertebra. • Conversely, when psoas muscle does not insert five lumbar bodies above the apparent lumbosacral joint, the probability of variation in the number of lumbar vertebrae is high.

The Impact of L5 Sacralization on Fusion Rates and Clinical Outcomes After Single-level Posterior Lumbar Interbody Fusion (PLIF) at L4-L5 Level

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

To determine the impact of L5 sacralization on fusion rates and clinical outcomes after single-level posterior lumbar interbody fusion (PLIF) surgery at the L4-L5 level.

SUMMARY OF BACKGROUND DATA

L5 sacralization can produce greater stress concentration at the adjacent segment (L4-L5); therefore, L4-L5 PLIF surgery in patients with L5 sacralization may negatively affect fusion rate and be associated with poor clinical outcomes. However, no study has examined the impact of L5 sacralization on fusion rates and clinical outcomes of patients who undergo L4-L5 PLIF surgery.

MATERIALS AND METHODS

Of 153 patients who underwent L4-L5 PLIF, data of 145 who met the study criteria were retrospectively reviewed. Among them, 31 patients had L5 sacralization (group A), whereas the remaining 114 patients did not (group B). The primary study endpoint was fusion rate evaluated using dynamic radiographs and computed tomographic scans. Secondary endpoints included (1) pain intensity in the lower back and radiating to the lower extremities on the visual analog scale; (2) clinical outcomes assessed using the Oswestry Disability Index and 12-item Short Form Health Survey; (3) surgical outcomes; and (4) complications.

RESULTS

Fusion rate evaluated using dynamic radiographs and computed tomographic scans at 6 months after surgery did not differ significantly between patients with and without sacralization (P=0.70 and 0.81, respectively), whereas fusion rate at 1 year after surgery did (P=0.04 and 0.04, respectively). In particular, patients with type II or III L5 sacralization had significantly lower fusion rates than those with other types of or no L5 sacralization. Pain intensity, clinical and surgical outcomes, and complications did not differ significantly between groups.

CONCLUSIONS

Patients with type II or III L5 sacralization may have worse fusion rates after L4-L5 PLIF surgery than those with type I or no sacralization.

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.

The Impact of Lumbosacral Transitional Vertebrae on Therapeutic Outcomes of Transforaminal Epidural Injection in Patients with Lumbar Disc Herniation

BACKGROUND

Although some studies have evaluated the clinical impact of lumbosacral transitional vertebrae (LSTV), few have attempted to determine an effective conservative treatment method for lumbar disc herniation (LDH) presenting concurrently with LSTV.

METHODS

We prospectively enrolled 291 consecutive patients who were followed-up for at least one year after transforaminal epidural injection (TFEI) for LDH. We confirmed the presence of LSTV with Paik et al.'s method, the Castellvi classification, and the Southworth and Bersack method. Clinical outcomes were evaluated with a visual analogue scale (VAS) for pain intensity and the Oswestry Disability Index (ODI) for functional status.

RESULTS

Of the 291 patients, 47 (16.2%) had LSTV, including 33 with sacralization and 14 with lumbarization, while 244 (83.8%) did not have LSTV. Patients in both groups improved significantly after TFEI in terms of the VAS (P < 0.001) and ODI (P < 0.001) scores. However, LDH patients with LSTV had a worse clinical outcome after six months of TFEI than did those without LSTV, with a significant difference between groups for both the VAS (P < 0.01) and ODI (P = 0.01) scores. LDH patients with sacralization had worse post-treatment clinical outcomes than LDH patients with lumbarization (P < 0.001) or LDH patients without LSTV (P < 0.001).

CONCLUSIONS

Sacralization can reduce the improvement after TFEI among LDH patients, while lumbarization appears to have no direct effect on TFEI outcomes. The presence of sacralization should be identified before TFEI, and if present, patients should be informed that the outcomes of TFEI may not be as good as they would be if sacralization was not present.

Numeric and morphological verification of lumbosacral segments in 8280 consecutive patients

STUDY DESIGN

An analysis of imaging data.

OBJECTIVE

To investigate concurrent numeric and morphological variations of presacral vertebrae and to propose a modified designation for the lumbosacral transitional vertebra (LSTV).

SUMMARY OF BACKGROUND DATA

During the assessment of the lumbosacral vertebra, variations from typical anatomy (numeric, morphological, or both) may confuse the practitioner, potentially leading to significant clinical errors. Common practice, which involves counting cephalad from the presumed fifth lumbar vertebra, may result in inaccurate localization of lumbosacral levels.

METHODS

The study group was composed of 8280 consecutive patients who underwent both lumbar magnetic resonance imaging with cervicothoracic scanning and lumbar radiographical examinations. The presacral vertebral number was verified by counting caudally from C2, with cross-referencing of cervicothoracic and lumbar sagittal scans on a picture archiving and communication system workstation. After correlating the numbering on the magnetic resonance images with those on the radiographs, the lumbosacral junction was classified according to the Castellvi's method.

RESULTS

Of the 8280 consecutive patients, 214 (2.6%) had 4 lumbar vertebrae (L4), 7384 (89.2%) had 5 lumbar vertebrae (L5), and 682 (8.2%) had 6 lumbar vertebrae (L6). Overall, 877 (10.6%) patients had LSTV of types II, III, or IV, including 439 (5.3%) with sacralized L5 vertebra and 438 (5.3%) with lumbarized S1 vertebra. The most common LSTV was L5-type vertebra with a unilateral type II transition, designated as L5IIa, in 222 (2.7%) patients. The second most common LSTV was L6-type vertebra with a bilateral type III transition in 174 (2.1%) patients that was designated as L6IIIb. Only 6945 (83.9%) of the population were modal type, with 5 lumbar vertebrae without transitional vertebra. All the 214 (2.6%) L4-type and 244 (2.9%) of the 682 L6-type patients presented with no transitional vertebra, looking like a modal L5-type patient.

CONCLUSION

Spine physicians and radiologists should consider the possibility of both numeric and morphological variations when evaluating lumbosacral spine images.