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 Table of Contents  
Year : 2020  |  Volume : 15  |  Issue : 1  |  Page : 98-107

Role of magnetic resonance imaging in the evaluation of low backache: Examining the disease spectrum

Department of Radiodiagnosis, Jawaharlal Nehru Medical College, Datta Meghe Institute of Medical Sciences (Deemed to be University), Wardha, Maharashtra, India

Date of Submission10-Oct-2019
Date of Decision30-Oct-2019
Date of Acceptance10-Nov-2019
Date of Web Publication13-Oct-2020

Correspondence Address:
Dr. Varghese Paul
Department of Radiodiagnosis, JNMC, Sawangi, Wardha, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jdmimsu.jdmimsu_150_19

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Introduction: The Spine Society of Europe defines low back pain (LBP) as the muscle tension or stiffness localized below the costal margin and above the inferior gluteal folds. LBP is a common musculoskeletal complain that can originate from ligaments, facet joints, vertebrae, paravertebral musculature, or spinal nerve roots. LBP lays a huge burden on the healthcare system. Aim: In this study, we analyze cases of LBP and conduct various studies within the framework of key domains of pain generators in LBP, namely (1) degenerative, (2) traumatic, (3) infectious, and (4) neoplastic etiologies. Materials and Methods: A total of 585 patients who underwent magnetic resonance imaging of lumbar spine/dorsolumbar spine with the complaints of LBP were selected for the study. The pathology was identified and grouped under one of the four entities mentioned above. Analytical tools were applied and the concerned inference was made for each case. Results and Conclusions:(1) Ligamentum flavum thickness has a positive correlation with age, severity of disc degeneration, facetal osteoarthritis, and sagittal orientation of facets at significance (P < 0.01). (2) The features of posterior element involvement, convex posterior border, and band signal are the ones with maximum differential power in differentiating benign and malignant vertebral compression fracture (P < 0001). (3) Thoracolumbar injury classification and severity score is a comprehensive and recent injury grading scale to classify spinal fractures and to provide valuable guidelines regarding diagnosis and management of spinal injuries with high accuracy. (4) Tuberculous spondylosis can mimic other infectious conditions such as spondylitis and also several other non-infectious conditions, and if some pitfalls are not considered, it might lead to wrong diagnoses.

Keywords: Facet orientation, Framingham scale, infectious spondylitis, ligamentum flavum, low back ache, Pfirrmann grade, thoracolumbar injury classification and severity score, vertebral compression fractures

How to cite this article:
Paul V, Kashikar S. Role of magnetic resonance imaging in the evaluation of low backache: Examining the disease spectrum. J Datta Meghe Inst Med Sci Univ 2020;15:98-107

How to cite this URL:
Paul V, Kashikar S. Role of magnetic resonance imaging in the evaluation of low backache: Examining the disease spectrum. J Datta Meghe Inst Med Sci Univ [serial online] 2020 [cited 2020 Oct 27];15:98-107. Available from: http://www.journaldmims.com/text.asp?2020/15/1/98/297970

  Introduction Top

The Spine Society of Europe defines low back ache (LBA) as the muscle stiffness or muscle tension which can be localized inferior to the costal margin and superior to the gluteal folds, present with or without radiculopathy, and is termed as chronic LBA when the symptom persists for 3 months or more.[1]

Low back pain (LBP) presents a large challenge to the healthcare system, despite improving scientific technology, medical insight, and suggested management strategies. LBP results in suboptimal performance at a personal as well as professional level and has significant psychosocial distress. Approximately 9%–12% of people (632 million) have LBP at any given point in time.[2] Hence, LBA is not just a disease condition that requires medical attention but, as a collective society point of view, also possess socioeconomic implications as well which raises the significance of such studies.

Many advantages of magnetic resonance imaging (MRI) such as better contrast resolution, absence of bony artifacts such as in computed tomography (CT) and X-ray, the capability to multiplanar image, and choice of a variety of sequences are the reasons why MR is considered gold standard for any spinal pathology.[3]

The lack of consummate and conclusive research, the pool of several contradicting study results, inadequate sizes of study samples, errors in methodology, and the cumbersome processes have all resulted in inability to form proper guidelines, and thus, inexpertise among radiologists and lack of precision in reporting as far as radiologists are concerned for the optimal diagnostic and management strategy for LBA.[4]

  Materials and Methods Top

This is a cross-sectional analytical study including all patients referred to the Department of Radiology, AVBRH, Sawangi, with clinically diagnosed LBA. A total of 555 patients were analyzed using GE 1.5 Tesla MRI over 2 years. The patients underwent MRI lumbar or dorsolumbar spine, and the pathology was identified and grouped under one of the four entities mentioned above. Relevant statistical methods were applied for each study.

Degenerative disease

A total of 399 cases of lumbar canal stenosis were studied (spinal canal anteroposterior diameter <8 mm). Ligamentum flavum (LF) thickness was measured at L4–L5 at the facet level. More than 4 mm LF thickness was considered thickened. Disc degeneration was classified into five grades, according to the modified Pfirrmann criteria. Facet joint osteoarthritis (OA) was graded to five scales, according to the Framingham scaling.

Facet orientation was based on facet angle, and it was classified into four groups: sagittalized, coronalized, mid-sagittalized, and mid-coronalized facet joints.

Vertebral compression fractures

The following eight MRI points were selected: posterior element involvement, paravertebral involvement, multilevel involvement, retropulsion, convex posterior border, preserved bone signal, band pattern in the vertebra, and sharp wedging.

Checklist of eight parameters was prepared for each case. The vertebral compression fracture (VCF) was confirmed as (1) malignant if histopathologically proven, and in patients which histopathological examination was not performed and a follow-up interval of 6 months was assigned and (2) benign vertebral fracture if it healed spontaneously within this time period with conservative management.

Traumatic lumbosacral spine

Thoracolumbar injury classification and severity (TLICS) scoring system was employed and is an attempt to validate the usefulness of this system wrt patient management and prognosis. The decision on whether to do surgery or adopt conservative management was based on the clinical criteria of a spine surgeon without information of the score of TLICS. In each case, the total TLICS score was derived. Cases were studied retrospectively as to whether the treatment instituted by the orthopedic discretion was correlating with what was recommended by TLICS scoring system and the accuracy in predicting diagnosis was determined.

Spinal infections and its mimics

Classical spondylitis refers to pyogenic infections even though tubercular spondylitis is the most commonly encountered infection in the spine in developing countries.

We aim to describe typical signal-intensity changes in tubercular infections opposed to classical pyogenic infections. We also discuss some common pathologies which could be confused with pyogenic spondylitis and how to differentiate them. The pathologies discussed will have similar imaging characteristics; however, other salient features which are helpful in making the correct diagnosis will be described.

Thus, the intention of this study is to cover comprehensively the various key domains of spinal pathologies, namely degenerative, traumatic, infectious, and neoplastic, and thereby to produce a research study of utility which incorporates into it, most of the spinal pathologies that we encounter in clinical practice.

Ethical clearance

Ethical clearance was obtained from the Institutional Ethical Committee of JNMC, Sawangi (Meghe), Wardha, on 6th May 2019. With ethical clearance no DMIMS(DU)/IEC/2019-20/336.

  Observations and Results Top

Degenerative disease

  • 399 patients had exclusive degenerative disease in the lumbosacral spine (216 males and 183 females). The age group of the subjects ranged from 17 to 81 years of age with a mean 48.57 ± 1.18955 years. The gender predilection in any age group was negated by P > 0.2 in all age groups.

  • Approximately 60% (59.6%) of the patients, i.e., 238 patients, had a thickened LF. Mean LF thickness was (4.54 ± 1.18 mm) – more than upper limit of normal.

  • A significant rise in the mean LF thickness was observed with advancing age group (P < 0.01) as given in [Table 1].
  • Pfirrmann Grade II, III, and IV (in terms of increasing severity) had significant association with mean LF thickness (P < 0.01) as given in [Table 2].
Table 1: Mean LF thickness in different age groups, standard deviation, and their significance of association by P-value

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Table 2: Mean ligamentum flavum thickness in different grades of Pfirrmann disc degeneration, standard deviation, and their significance of association by P-value

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[Table 2] shows the mean LF thickness in different grades of Pfirrmann disc degeneration, standard deviation (SD), and their significance of association by P value.

  • Framingham Scale II, III, and IV (in terms of increasing severity) had significant association with mean LF thickness (P < 0.01) as shown in [Table 3].
  • Table 3: Mean ligamentum flavum thickness in different grades of Framingham facetal osteoarthritis, standard deviation, and their significance of association by P-value

    Click here to view

    [Table 3] shows the mean LF thickness in different grades of Framingham facetal OA, SD, and their significance of association by P value.

  • Mid-sagittalized and mid-coronalized facets were significantly associated with LF thickness (P = 0.0006 and 0.002, respectively). There was a steady increase in mean LF thickness with increasing sagittalization as shown in [Table 4].
Table 4: Mean ligamentum flavum thickness in different types of facetal orientations, standard deviation, and their significance of association by P-value

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[Table 4] shows the mean LF thickness in different types of facetal orientations, SD, and their significance of association by P value.

Vertebral compression fractures

  • 49 cases were studied under this category and 37 were deemed benign and 12 malignant based on our criteria. Five of the features demonstrated significant association (P < 0.001). Highest accuracy for malignancy was provided by pedicle/posterior involvement (94%) and convex posterior border (92%) of the vertebra and band pattern (92%). Combining these three features yielded a predictive value of 98%.
  • Based on the above findings, relevant statics were drawn out, and sensitivity and specificity calculated for each parameter are given in [Table 5].
  • Table 5: Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of diagnosis of all the 8 parameters under the study

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    [Table 5] shows the sensitivity, specificity, positive predictive value (PPV), negative predictive value, and accuracy of diagnosis of all the eight parameters under the study.

  • Based on the above findings, odds ratio (OR) and P value at 95% confidence interval were drawn out and are given in [Table 6].
Table 6: Odds ratio, significance of association by P value, and 95% confidence interval of all the 8 parameters under the study

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[Table 6] shows the OR, significance of association by P value, and 95% confidence interval of all the eight parameters under the study.

Traumatic lumbosacral spine

  • 49 cases of spinal trauma were evaluated. 33 were managed conservatively whereas 16 underwent surgical management. Of the 49 patients, 32 patients had a TLICS score ≤3. TLICS score of 4 was seen in three patients. 14 patients had a TLICS score ≥5
  • 92% of the patients, i.e., 29/32, matched TLICS conservative treatment recommendations when score was ≤3. 84% of the patients, i.e., 12/14, matched TLICS surgical treatment recommendations when score was ≥5 as per the data given in [Table 7]
  • Of the three cases of TLICS score of 4, one patient was treated conservatively while two underwent surgery. Three cases of “violation” of TLICS were observed. One case of nonsurgical score underwent operation due to unbearable pain, while two cases of surgical score were not operated due to patient instability
  • Keeping these cases of violations and the cases with TLICS score of 4 as 100% match (surgical or conservative out of relevance), 47 out of 49 patients were managed in accordance with the TLICS recommendation, i.e., with a diagnostic accuracy of 96% [Table 7]
  • Mean LF thickness was found to be in the surgical group and in the conservative group with higher TLICS, suggesting higher incidence of surgical management as per the significance of association given by P < 0.001 [Table 8].
Table 7: Patients in both the groups (conservative and surgical), the number of cases which corresponded to thoracolumbar injury classification, and severity recommendation with inclusion of the violations and the diagnostic accuracy in each group

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Table 8: Number of patients in each group (conservative and surgical), the corresponding thoracolumbar injury classification and severity score in each of the 2 groups with comparison of the mean thoracolumbar injury classification and severity score with standard deviation with a significant P value in both the Groups

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[Table 7] shows the patients in both the groups (conservative and surgical) and the number of cases which corresponded to TLICS recommendation with the inclusion of the violations and the diagnostic accuracy in each group.

[Table 8] shows the number of patients in each group (conservative and surgical) and the corresponding TLICS score in each of the two groups with comparison of the mean TLICS score, with SD with a significant P value in both the groups.

Spinal infections and its mimics

  • Of the 85 cases that were studied, 47 were of tuberculous spondylitis while eight were cases of pyogenic spondylodiscitis
  • A few other cases with similar imaging findings affecting a single spinal segment were identified as potential pitfalls, i.e., Modic Type I changes and acute cartilaginous node. Features such as multifocal involvement, relative preservation of the disc, and paravertebral ring enhancing involvement were found almost exclusively in tuberculous spondylitis compared to pyogenic infection and other disease entities.

  Discussion Top

Degenerative disease of the spine is by far the most common etiology of chronic back pain. We have included only cases with stenosis of the lumbar spinal canal. Various mechanisms have been proposed which culminate in this narrowing of the spinal canal:[5]

  1. Posterior marginal osteophytes
  2. Intervertebral disc herniation
  3. Hypertrophy of ligamentum flavum (LF)
  4. Facet joint OA with hypertrophy of articular facets
  5. Epidural fat, if in excessive amount.

In our study, we have taken into account the major abovementioned mechanisms by which there can be a spinal canal stenosis.

LF by itself is the very focal point of our study, the nucleus around which other entities have been observed. The LF was measured for each and every case, and the progressive thickness of LF has been exhaustively studied in comparison with age, facetal arthropathy, disc degeneration, and facet tropism. The upper limit of a normal LF thickening was considered as 4 mm as per various studies.[6],[7]

For the purpose of this study, patients who have other conditions such as spinal trauma, spinal infections, congenital deformities, as well as metabolic derangements have been excluded to make the study more pristinely focused on chronic back pain as a result of age-related degenerative changes.

The degenerative changes are most pronounced and more apparent at L4–L5 level than any other single spinal level in terms of frequency.[8],[9] Taking into account this fact, we have analyzed one particular spinal column at one particular level, i.e., the L4–L5 disc level. Measurements such as LF thickening, facet angle measurements, joint orientation calculation, Pfirrmann disc degeneration, and facet joint OA were all calculated or graded at L4–L5 level. In our study, we have included cases with normal disc height at L4–L5 level, whether as to examine whether the apparent LF thickening is due to just buckling due to disc collapse or a true hypertrophy. Increasing LF thickness is associated with increase in fibrotic content of the LF and a decrease in elastic component.[10]

In our study, the mean LF thickness increased with increasing age group as observed in the tables. Patients with 10–19 years of age group had a LF thickening of only 2.62 ± 0.25 mm, whereas in patients in the age group >70, the mean LF thickness was 6.99 ± 0.35 mm (P < 0.001).

In our study, we have also examined that the degree of disc degeneration at L4–L5 by applying the Pfirrmann grading system for the disc degeneration found a rather strong correlation between the increasing degree of disc degeneration and LF thickness. Grade II Pfirrmann (34 cases) had a mean LF thickness of 3.44 ± 0.66 mm (P < 0.001) which is clearly lower compared to the mean LF thickness of Grade IV (228 cases), which was 5.09 ± 1.14 mm (P < 0.001). This result was similar to the study of Yoshiiwa et al., who found a direct relationship between increasing degenerative disc changes and increasing thickness of LF.[11] Shekarchi and Momeni however found only a loose association of disc degeneration with LF thickening.[12]

Wang and Yang proved that coronal L4–5 facet joint orientation correlated with age but negatively.[13] In our study, we could observe a greater LF thickness in association with a facet joint which is more sagittal orientated and FJO. There was a steady increase in the mean LF thickness as the facets became more sagittalized, i.e., coronalized facets had mean LF thickness of 2.85 ± 0.34 mm (P = 0.016) and sagittalized facets had a mean LF thickness of 6.23 ± 0.79 mm (P < 0.51).

Facet orientation study established that more the facet joint is oriented laterally (sagittalized), more is the LF thickness and hence overall degenerative changes in the spine. This was in accordance with the study conducted by Kalichman et al., who stated that increased sagittalization of the facet joint was a risk factor for degenerative spondylolisthesis and correlated with increasing patient age.[14]

In our study, Framingham I cases had a mean LF thickness of 2.50 ± 0.21 mm, Grade IV had a mean LF thickness of 5.97 ± 0.99 mm, and a positive correlation was established between LF thickness and increasing severity of facetal arthropathy (P < 0.001). Karavelilogu et al. a study in similar lines where they proved suggest that LF thickening may occur alone or in association with facet joint degeneration with significant correlation with age.[15]

Through our study, we could successfully and statistically demonstrate that increasing thickness of LF thickness, increasing age, advancing disc degeneration, and facetal joint morphology (including OA and increasing sagittalization of facet angle) even though independent factors (as confirmed by logistic regression) were all interrelated to each other and directly proportional to each other as signified by a P < 0.001

One can effectively state that all these factors concerning age, disc degeneration, facetal arthropathy, and LF thickening even though independent factors (as confirmed by logistic regression) are all part of the overall spectrum of spinal degenerative disease and have significant positive correlation with each other (P < 0.01).

VCF is a common entity encountered in clinical practice. Although plain radiographs are often enough for an accurate diagnosis of a VCF, it cannot differentiate between benign or malignant collapse. Thus, MRI is considered the gold standard diagnostic modality.[16]

VCF can be traumatic in nature or can occur as a spontaneous event, and in this section, we are only dealing with spontaneous VCFs (which occur without a precipitating trauma).[17]

These fractures can either be of a benign or malignant nature. The most important cause of benign fractures is osteoporosis and malignant is metastases to the spine.

Eight MRI features were studied and compared to extract their differential power. The aim of the study was to identify those features holding maximum relevance and which were the most reliable features for diagnosis of osteoporotic and metastatic vertebral fractures.

Our analysis results showed that each of the eight MRI features had a separate meaning and variable differentiation power. As evidenced by the ORs, to varying degrees, the features of posterior element involvement, paravertebral involvement, convex posterior border, and multilevel involvement were malignant features (OR > 1), while retropulsion, sharp wedging, preserved signal, and band pattern were benign features (OR < 0). The results were in accordance with the systemic review by Thawait et al., who associated seven malignant features and seven benign features for the purpose.[18]

As per our analysis of P value, the features of retropulsion of vertebra and multilevel involvement were deemed insignificant because of P > 0.02.

The highest diagnostic accuracies were given by three factors: pedicle or posterior element involvement (93%), presence of band pattern at vertebral endplates (92%), and convex posterior border (92%) at P < 0.01.

Reasonable differential power was displayed by other features such as paravertebral involvement, sharp wedging, and preserved marrow signal (P < 0.01) also, but they could not statistically outperform the abovementioned three factors.

Our analysis of the current MRI findings combined the features with “highest diagnostic accuracy,” i.e., malignant features of the convex posterior border (OR 180) and posterior element involvement (OR 87.5) along with the benign feature of band pattern (OR 0.008) of the affected vertebra as evidenced by their ORs.

When these three criteria were simultaneously applied to the cases individually, i.e., the presence of posterior element involvement, the presence of convex posterior border, and the absence of band pattern, 48/49 cases could be classified accurately as benign or malignant. In other words, combining these three MRI features allowed accurate diagnoses with a predictive value of 98%. Benign (osteoporotic) fractures are more likely under circumstance of the presence of band pattern and absence of the above posterior element involvement and convex posterior border, and tissue sampling can be deferred since the probability of malignancy is only 2%.

The TLICS was developed by the Spine Trauma Study Group in view of the fact that the classification system that was previously used and was prevalent at the time had a relatively poor performance in predicting the prognosis of the injury and suffered from the ineffective management guidelines, which had a profound effect on the treatment decision.[19]

The TLICS classification system takes into account three components and provides an injury severity score based on three different and independent components:

  1. Vertebral fracture morphology
  2. Structural integrity of the planar light-wave circuit (PLC)
  3. Neurologic status of the patient.

TLICS focuses on the morphology of injury rather than the mechanism unlike the prevalent system of the time, “Denis 3 Column Classification.”

The TLICS emphasizes the importance of the PLC, and it recognizes the role of an intact PLC in maintaining spinal stability. This scoring system, by assimilating within itself the neurological condition, has acknowledged its role as the primary driver as to which the decision whether to operate the patient or not is drawn against.[20]

Total score is calculated per patient as a total of the three individual components to arrive at a total score. A total score ≤3 generally indicates nonsurgical management with immobilization with the help of a brace and active ambulation. A total TLICS score of ≥5 warrants immediate surgical intervention with the correction of the occurred deformity, decompression, and subsequent stabilization of the vertebral fracture and ligaments. Score of 4 is an intermediate zone and the decision whether to operate or not is determined by the orthopedic surgeon managing the case. This is a scenario where both surgical and nonsurgical treatment may seem equally appropriate.

In our study, we encountered 49 consecutive cases of spinal trauma and the information regarding the immediate management the patient underwent posttrauma (conservative/surgical) was obtained along with a follow-up period of period of 4 weeks to identify any crossover between conservative and surgical management groups.

The average of the total TLICS score in patients who underwent surgical management was 6.19 ± 1.52 and the average of the total TLICS score in patients who underwent conservative management was 1.48 ± 0.67; significance denoted by P < 0.01.

There were three cases of violation, i.e., the patients were initially deemed as requiring a particular modality of treatment but later on crossed over to the other group because of various reasons. For example, one patient on whom conservative management was resumed; during the period of hospital stay, he developed intense pain which prompted the orthopedic surgeon to take up the patient for surgery. Two patients on whom it was decided to operate could not undergo surgery because of the clinical instability.

Including these cases of violations as correspondence, and adding patients with a total TLICS score of 4 as corresponding patients, 94% of the patients in the nonsurgical (conservative) group and 97% of the patients in the surgical group demonstrated agreement with the TLICS prediction at a P < 0.001 emphasizing the significance.

Including both the groups as a whole, 47/49 patients were accurately directed into appropriate management using TLICS scoring system with an accuracy of 96% empowering us with the knowledge that the TLICS provides one of the most comprehensive and accurate predicting models for surgical versus nonsurgical management and should be propagate further in the community of radiologists as well as orthopedic surgeons.

One of the objectives of our study was to describe spinal infections in-depth. As far as our study regarding spinal infections was concerned, it was descriptive in nature more than analytical. In developing countries like ours, Koch's is a very rampant disease,[21] and tuberculous spondylitis is a common extrapulmonary manifestation of tuberculosis.[22]

In early stages of a Pott's spine, however, the characteristic features might not be visible and may mimic other pathologies of the spine such as pyogenic spondylitis,[23] in some cases even noninfectious processes. Certain pathologies which involves a single spinal segment and can be differential diagnoses of each other, especially in the early stages of the disease:

  • # Tuberculous spondylodiscitis # Pyogenic spondylodiscitis
  • #  Brucella More Details spondylodiscitis # Fungal osteomyelitis
  • # Acute Schmorl's node # Ankylosing spondylitis
  • # Neuropathic spine # SAPHO syndrome

The typical appearance is the affected vertebrae being hypointense on T1-weighted images and hyperintense on T2-weighted images with fluid intensity signal from the intervening disc.[24]

85 cases having the typical appearance (single spinal segment involvement with vertebra showing hypointense on T1-weighted imaging [T1-WI] and hyperintense on T2-WI) were encountered across the time of this study.

The final diagnosis was confirmed based on either the clinical outcome of the patient or based on histopathology report whenever available.

Of these 85 cases under study, 47 cases were of tuberculous spondylodiscitis. Pyogenic spondylodiscitis was the final diagnosis in eight of the total cases. There were 24 cases of Modic I changes six cases of acute cartilaginous node, which resembles spinal infections. There were no cases of Brucella spondylitis or fungal osteomyelitis.

Pyogenic spondylitis is the condition which most accurately demonstrates our typical criterion of single spinal segment involvement. Classical pyogenic spondylitis matches the typical criterion. Spinal infections shows signal intensity on T1-WI and T2-WI (hypointense and hyperintense, respectively) and shows enhancement postcontrast enhancement.[24]

MRI shows vividly enhancing, epidural extension of disease better than any other modality.[25] Epidural extension was seen in most of the cases of spinal infection, both pyogenic and tuberculous. Paravertebral and epidural disease shows mixed intensity diffuse more than rim enhancement.[26]

In cases of tuberculous spondylitis, a long-standing history is more likely to be tuberculous spondylitis. In most of our cases, the pathology starts in the paradiscal region and more anteriorly (as evidenced by the cases which presented to us at an early stage). The lack of proteolytic molecules in the bacteria is the cause of the relative preservation of the intervening disk and also the pattern of spread (subligamentous in nature).[27]

The presence of a well-defined paraspinal lesion with thin rim enhancement was more suggestive of tuberculous spondylitis. Spread of the disease to more than three vertebrae consecutively is also a feature of tuberculous spondylodiscitis.

The presence of skip lesions was seen in much greater frequency in tuberculous spondylitis, compared to other pathologies under discussion. MRI is less sensitive for calcification of the paraspinal abscess and is seen clearly in CT or X-ray which was not appreciable much and not included as a valuable MRI criteria for diagnosis.

In theory, Modic type 1 degeneration may resemble infectious spondylitis, especially the early stages of pyogenic spondylitis, which shows high-signal intensity on T2-WI images and most so if the patient is afebrile. In some cases, contrast enhancement might be seen in the affected bone marrow due to the inflammation and edema along with enhancement of the affected disk; this has been reported widely in the literature.[28]

In our study, all the cases of Modic I matched the “typical criterion,” but the absence of disc involvement, i.e., normal signal from the disc, and the sparing of para-vertebral soft tissue were the characteristic findings that helped us to separate Modic type 1 degeneration from infectious spondylodiscitis. Postcontrast enhancement was also variable and was appreciable only in few cases. Unless there is bony destruction, fluid intensity from the concerned disc or soft tissue encroachment, Modic type 1 degeneration, should be suspected.[29]

Acute traumatic cartilaginous node is usually seen in cases of trauma and is identified when there is marrow edema that surrounds an extruded disc into a vertebra. On MRI features alone, this entity is often not differentiated from infectious spondylitis.[30]

In our limited cases of acute traumatic cartilaginous node, T2 hyperintense concentric ring was seen adjacent to the Schmorl's node. This was in addition to the vertebral body edema in the background. This is the typical feature which was useful in distinguishing an edematous node from infectious spondylitis. Contrast enhancement was variable and nonspecific and hence not included as a criterion for differentiation between the two entities.[31]

These differential diagnoses gains relevance when the infectious processes is at its early stage and without proper history, observation of imaging findings, and consideration of the differential diagnoses one might jump into a wrong diagnosis. Since treatment modalities vary considerably between these clinical conditions, a misdiagnosis might prove costly for the patient as well as the radiologist[Figure 1],[Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11].
Figure 1: Axial T2-weighted imaging at L4–L5 level illustrating the method of measurement of facet angle; facet angle is angle subtended by the facet line on one side and the mid-sagittal line (measured as 34.9° in this case) This is a typical Mid-Sagittalized FJ

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Figure 2:(a) Sagittal and axial T2 images demonstrating normal disc height at L4–L5 with heterogeneously hypointense signal but perceptible annulus-nucleus distinction - Pfirrmann Grade II disc. (b) Facet joint shows normal joint space without any osteophytes or subchondral changes - Grade I Framingham scale ligamentum flavum as measured at L4–L5 facet level is 3.1 mm (normal) Facet lines are drawn and the angle subtended at the midline is 83° (facet angle) - coronalized facet

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Figure 3: (a and b) Facet joint showing moderate-sized osteophytes with a reduced facet joint space and hypertrophy of articular process causing neural foraminal compromise bilaterally. No e/o subchondral changes - Grade III Framingham facet lines are drawn and the angle subtended at the midline is around 8° - sagittalized Facet

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Figure 4:(a) 63-year-old female, k/c/o carcinoma thyroid on chemotherapy and radiation presented with low backache and paraplegia. Sagittal T2, sagittal T1 + C, and coronal T1 + C images show collapsed D12 vertebra with altered signal intensity showing homogenous enhancement, paravertebral involvement, and posterior element involvement. Note the enlarged thyroid gland. (b) Axial T2-weighted imaging show distorted morphology of the vertebra with involvement of the pedicle and bilateral laminae. Histopathology proven malignant vertebral compression fracture

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Figure 5: (a) 80-year-old female, fall from chair, came with severe back pain and restriction of movements. Sagittal and coronal T2-weighted imaging show anterior wedging fracture of D12 with slight retropulsion of the affected vertebra. Note preserved signal from the vertebra. (b) Axial T2-weighted imaging show normal pedicle and bilateral laminae with preserved morphology and signal intensity. Patient was managed conservatively and recovered within 8–10 weeks

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Figure 6: (a) Sagittal T2-weighted imaging showing a burst compression fracture of the D12 along with retropulsion of the vertebral body to cause narrowing of the spinal canal. There is an uncomplicated vertebral compression fracture of L1 vertebra as well. Hyperintensity noted in the posterior longitudinal ligament interspinous ligament and supraspinous ligament. Vertebral injury score – 2 (Burst fracture) and planar light-wave circuit Injury Score – 3 (disrupted planar light-wave circuit). (b) Axial T2 weighted imaging showing the fractured vertebral body along with intramedullary hyperintensity s/o spinal cord edema. Ligamentum flavum shows disruption of fibers and altered signal intensity. Planar light-wave circuit injury score – 3 (disrupted planar light-wave circuit). Neurological deficit score – 3 (incomplete spinal injury) and total thoracolumbar injury classification and severity score 8. Patient underwent combined approach spinal decompression

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Figure 7: (a) Sagittal T2-weighted imaging showing a simple compression fracture of L1 vertebra. Ligamentum flavum, interspinous and supraspinous ligament show normal morphology and signal intensity. Vertebral injury score – 1 (simple compression fracture). planar light-wave circuit injury score – 0 (intact planar light-wave circuit). (b) Axial T2-weighted imaging showing normal ligamentum flavum, interspinous and supraspinous ligament show normal morphology and signal intensity. Neurological deficit score – 0 (neurologically asymptomatic). Total thoracolumbar injury classification and severity score – 1. Patient was put on conservative management

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Figure 8: (a) 55-year-old patient, k/c/o pneumonia with sepsis; consulted to orthopedics with non-mechanical low back ache and shooting pain to limbs. Sagittal T1- and T2-weighted imaging show altered signal in L4, L5 vertebrae, appearing hypointense and hyperintense respectively. There e/o a T2 hyperintense pre-vertebral collection. Abnormal signal intensity of the intervening disc whereas no obvious destruction is observed in affected vertebrae. Note the characteristic involvement of single spinal segment. (b) Coronal T2-weighted imaging reveal hyperintensity in the L4 and L5 vertebrae along with the L4–L5 intervertebral dis. Note the homogeneously hyperintense right paravertebral collection This case was a histopathological examination proven case of Staphylococcus aureus pyogenic spondylitis

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Figure 9: (a) 81-year-old male presented with low back ache and low-grade fever since 2 months. Patient is a k/c/o pulmonary tuberculosis inadequately treated. Sagittal T1- and T2-weighted imaging shows that L2 and L3 vertebra appear heterogeneously hypointense and hyperintense respectively. L2–L3 disc shows heterogeneous signal intensity. No epidural or prevertebral collection. Note characteristic involvement of a single spinal segment. (b) Coronal T1+C image showing heterogeneous pattern of enhancement of the L2 and L3 vertebra with preserved intervertebral disc. No e/o paravertebral collection. However there is patchy enhancement in the paravertebral region including the psoas muscle. This was a histopathological examination proven case of early tuberculous spondylitis which was mimicking pyogenic spondylitis due to the single level involvement and absence of collections. Observe the early stages of tuberculous spondylitis mimicking pyogenic spondylitis

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Figure 10: Sagittal T1- and T2-weighted imaging shows that L4 and L5 vertebra appear heterogeneously hypointense and hyperintense respectively more prominently at the vertebral end-plates. L4–L5 disc height is reduced with dis desiccation. No epidural or prevertebral collection. Note characteristic involvement of a single spinal segment. Case of Modic I endplate changes

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Figure 11: Sagittal T1 and STIR i mages show altered signal in the D12 to L2 vertebrae appearing hypointense on T1 weighted imaging and hyperintense on STIR. There is extrusion of the L1–L2 and L2–L3 disc into the respective superior endplate with perinodal edema. The intervening discs show relatively normal signal intensity and height. Anterior wedging of D12 noted. No epidural or prevertebral collection. Involvement of a single spinal segment is present at contiguous levels. Case of acute Schorsl's node

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  Conclusion Top

  1. LF thickening is due to a true hypertrophy rather than mere buckling, and its contribution to lumbar spinal canal stenosis is pathological and reflects the overall degenerative process of the spine in general as it has significant positive association with age, severity of disc degeneration, and severity of facetal OA and is also associated with increasing degree of sagittalization of the facets (P < 0.001)
  2. Several points of differentiation are described to distinguish benign (osteoporotic) and malignant (metastatic) VCFs, but three features of posterior element involvement, convex posterior border, and band signal at the end-plates are the ones with maximum differential power and when combined together, had an overall PPV of 98%
  3. TLICS is a robust and valid injury classification system for thoracolumbar spinal injuries and has a high diagnostic accuracy (overall 96%) with respect to patient management and the type of treatment instituted
  4. Several infectious and noninfectious conditions present with involvement of a Single Spinal Segment either in Isolation or background disease. Tuberculous and pyogenic spondylodiscitis, Modic I endplate changes and acute Schmorl's nodes can present as differential diagnoses to each other at some point of the disease process, however, with careful observation and certain differentiating points kept in mind, it is possible to avoid diagnostic pitfalls.

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11]

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8]


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