Imaging of Tuberculosis

Hounsfield Units as an Independent Predictor of Failed Percutaneous Drainage of Spinal Tuberculosis Paraspinal Abscess Under Computed Tomography Guidance

OBJECTIVE

To investigate the value of Hounsfield units (HUs) as an independent predictor of failed percutaneous drainage of spinal tuberculosis paraspinal abscess under computed tomography (CT) guidance.

METHODS

A retrospective analysis was conducted on 61 patients who underwent CT-guided percutaneous drainage for spinal tuberculosis paraspinal abscess between October 2017 and October 2020. Preoperative CT scans were used to measure the HUs of the abscess. Patients were categorized into successful drainage (n = 49) and failed drainage (n = 12) groups. Statistical analysis involved independent sample t-tests and chi-square tests to compare between the 2 groups. Binary logistic regression was performed to identify independent predictive factors for drainage failure. Receiver operating characteristic (ROC) curves were employed to ascertain risk factor thresholds and diagnostic performance.

RESULTS

Among the patients, 49 experienced successful drainage while 12 faced drainage failure. The mean HUs of abscesses in the failed drainage group were significantly higher than those in the successful drainage group (p < 0.001). ROC analysis revealed an area under the curve of 0.897 (95% confidence interval, 0.808-0.986) for predicting drainage failure based on HUs. The optimal HU cutoff value for predicting drainage failure was 22.3, with a sensitivity of 91.7% and specificity of 69.4%.

CONCLUSION

HUs are an independent predictor of failed percutaneous drainage of spinal tuberculosis paraspinal abscess under CT guidance. The HU value of 22.3 can be used as an initial screening threshold for predicting the success or failure of drainage.

Childhood TB: when to think of it and what to do when you do

Although childhood tuberculosis has declined dramatically in the UK over the last century, it is now increasing again and globally childhood tuberculosis still accounts for a significant proportion of the tuberculosis disease burden. Children may present with non-specific symptoms, and because of the paucibacillary nature of disease and the difficulty of producing sputum samples, tuberculosis in children is often difficult to diagnose. Apart from the traditional diagnostic methods, like chest X-ray, tuberculin skin testing and mycobacterial staining or culture, new diagnostic strategies have been developed. In particular, immune-based diagnostics, such as interferon-gamma release assays, have now been introduced for clinical use. However these tests do not offer substantial improvements in sensitivity over tuberculin skin testing for the diagnosis of active disease. Further research is needed to develop better diagnostic tests for tuberculosis in children.

Imaging findings of Pott's disease

Tuberculosis (TB) continues to be an important public health problem in developed countries especially in deprived socioeconomic groups, older people, immunocompromised patients, drug-therapy resistant cases and the immigrant population. The spine is the most frequent location of musculoskeletal TB. The wide range of clinical presentations results in difficulties and delays in diagnosis. Advanced disease mimics other infections and malignancy. The diagnosis of spinal infections relies on three main factors: clinical symptoms, imaging and bacteriological culture. Advanced imaging such as Magnetic Resonance Imaging (MRI), Multidetector Computed Tomography (MDCT) and Fluor18-Deoxiglucose Positron Emission Tomography combined with CT (F-18 FDG PET-CT) demonstrate lesion extent, serve as guide for biopsy with aspiration for culture, assist surgery planning and contribute to follow-up. Diagnosis of TB cannot be established solely on the basis of clinical tests or imaging findings and biopsy may be required. Differential diagnosis between tuberculous and pyogenic spondylitis is of clinical importance, but may be difficult on the basis of radiological findings alone. Findings not pathognomonic but favoring tuberculous etiology include: slow progression of lesions with late preservation of disk space, involvement of several contiguous segments, large intraosseous and paraspinal abscesses containing calcifications, and body collapse with kyphotic deformity. In this essay the highlights of TB imaging are reviewed through published literature. In addition, we review retrospectively the radiological findings of 48 patients with tuberculous spondylitis treated from 1993 to 2010. There were 23 male and 25 female patients with a mean age of 53 years.

[Pott's disease (about 16 cases)]

INTRODUCTION

Pott's disease or spinal tuberculosis is rare, but represents the most common form of osteo-articular tuberculosis in endemic countries.

MATERIAL AND METHODS

[corrected] From January 2000 to December 2010, we collected 16 cases of Pott's disease. We analyzed clinical and radiological profile, means of confirmation and treatment.

RESULTS

Spinal and chest pain were the most frequent signs. Four patients had neurological signs. The diagnosis was made by the detection of bacillus in the pus of paravertebral abscess in six cases, by histological study of vertebral biopsy in five cases, biopsy of another associated lesion in one case and in front of radio-clinical arguments with good clinical evolution under antibacillary treatment in four cases. The antibacillary treatment associating four drugs was indicated and correctly followed by all patients. Surgical drainage was associated in five cases. The evolution was good in all cases.

DISCUSSION

Diagnosis of Pott's disease is late when there is no neurological sign. Imaging allows to make early diagnosis with MRI. Prognosis is good when treatment is started early.

Magnetic resonance evaluation of tubercular lesion in spine

PURPOSE

Information on Magnetic Resonance (MR) features of active and healed lesions in tuberculosis (TB) spine are lacking. We evaluated MRI findings in active and healed proven TB spine to establish the diagnostic features.

MATERIALS AND METHOD

Forty-nine consecutive spinal TB patients (20 male; 29 female) diagnosed clinicoradiologically and/or on histopathology, Fine Needle Aspiration Cytology (FNAC), bacteriology, or Polymerase Chain Reaction (PCR) were enrolled. Pretreatment MR scans were reviewed for diagnostic features, and eight-month follow-up MR scans were reviewed for healing changes.

RESULTS

Cervical spine (n = 6), dorsal spine (n = 14), and lumbar spine (n = 29) were affected. Fourteen had paraplegia. Mean vertebrae involved were 2.61 on X-ray with a total of 128 vertebrae (VB) and 3.2 on MRI (range, 2-15) with 161 VB. The lesions were more extensive on MRI (34.7%) than appreciated on X-ray. The disc was preserved partially or fully in 88.2% of instances. End plate erosions (159/161 VB), lost VB height (94/161), exudative lesion (158/161), granular lesion (3/161), pre and paravertebral collections (49/49 cases), marrow oedema (161/161), discitis (98%), epidural involvement (107/161), epidural spread (100/161), and subligamentous spread (156/161) were observed. Canal encroachment (10-90%) was seen in 37 cases. Mean motor and sensory scores with greater than 50% canal encroachment were 87/100 and 156/168, respectively. Cord oedema was observed in 11 cases (eight with neural deficit and three cases without). Cord atrophy was seen in one case each before and after treatment. A total of 83% of patients had a combination of paravertebral collections, marrow oedema, subligamentous and epidural extension, endplate erosions and discitis. On healing (n = 20), complete resolution of marrow oedema and collections, fatty replacement of bone marrow and resolution of cord signal intensity were observed.

CONCLUSION

The marrow oedema, preservation of disc space, subligamentous extension of abscess, septate paravertebral abscess, epidural extension, endplate erosions and discitis were consistently observed in 83% cases of TB spine on MRI.

Spinal tuberculosis: a review

Spinal tuberculosis is a destructive form of tuberculosis. It accounts for approximately half of all cases of musculoskeletal tuberculosis. Spinal tuberculosis is more common in children and young adults. The incidence of spinal tuberculosis is increasing in developed nations. Genetic susceptibility to spinal tuberculosis has recently been demonstrated. Characteristically, there is destruction of the intervertebral disk space and the adjacent vertebral bodies, collapse of the spinal elements, and anterior wedging leading to kyphosis and gibbus formation. The thoracic region of vertebral column is most frequently affected. Formation of a 'cold' abscess around the lesion is another characteristic feature. The incidence of multi-level noncontiguous vertebral tuberculosis occurs more frequently than previously recognized. Common clinical manifestations include constitutional symptoms, back pain, spinal tenderness, paraplegia, and spinal deformities. For the diagnosis of spinal tuberculosis magnetic resonance imaging is more sensitive imaging technique than x-ray and more specific than computed tomography. Magnetic resonance imaging frequently demonstrates involvement of the vertebral bodies on either side of the disk, disk destruction, cold abscess, vertebral collapse, and presence of vertebral column deformities. Neuroimaging-guided needle biopsy from the affected site in the center of the vertebral body is the gold standard technique for early histopathological diagnosis. Antituberculous treatment remains the cornerstone of treatment. Surgery may be required in selected cases, e.g. large abscess formation, severe kyphosis, an evolving neurological deficit, or lack of response to medical treatment. With early diagnosis and early treatment, prognosis is generally good.

Noncontiguous spinal tuberculosis: incidence and management

Tuberculosis (TB) has a worthy reputation as one of the great mimickers in medicine with a multitude of clinical pictures and variations. Noncontiguous spinal TB is described as atypical and case reports are published as rarities in the mainstream academic journals. The aim of the study was to asses the incidence and review of the management of non-contiguous spinal TB. We identified 16 cases of noncontiguous spinal TB from a single surgeon series of 98 patients, who were managed surgically between 2001 and 2006. These were diagnosed on whole spine MRI. This represents the largest series reported in literature to date and is higher than the expected incidence. Case notes and imaging were retrospectively reviewed in an attempt to ascertain if there were any parameters to differentiate this group from the rest of the TB spine population. Our incidence of noncontiguous spinal TB is 16.3%. There was a higher incidence of neurology in the noncontiguous group (75%) compared to the rest of our group (58.5%). Non-contiguous TB was not found to be a manifestation of HIV, MDR TB or of chronicity in our series. Most noncontiguous lesions were evident on plain radiology. Noncontiguous spinal TB is common in areas of high prevalence such as South Africa. Despite being frequently missed initially, noncontiguous involvement is evident on plain radiography and simply requires a higher index of suspicion. When investigating spine TB patients, simple radiology of the entire spine is mandatory. If available, a full spine sagittal MRI is extremely useful in identifying noncontiguous lesions. Treatment of noncontiguous tuberculosis is as for standard spinal TB cases in our unit with similar outcomes, but care needs to be taken in surgical planning as patients may have multiple areas of neurological compromise.

Medical management of Pott disease in the thoracic and lumbar spine: a prospective clinical study

OBJECT

The aim of this study was to evaluate conservative medical management of 44 patients with Pott disease. The prognostic significance of various clinical, radiological, and long-term follow-up findings in these patients was also evaluated.

METHODS

Between January 1990 and January 2005 data were collected prospectively at the authors' clinic in 44 patients with Pott disease in the thoracic or lumbar spine. These patients had no major neurological deficits or severe spinal deformities. The study population consisted of 21 male (48%) and 23 female (52%) patients, with a mean age of 42.1 years (range 10-70 years). The most common region of Pott disease was the thoracolumbar junction (18 cases; 41%), followed by the thoracic (16 cases; 36%) and lumbar (10 cases; 23%) regions. All patients presented with abscesses. With the exception of two cases, all had kyphotic angles smaller than 30 degrees. At presentation, 20 patients had neurological signs of spinal cord compression during clinical examination. Both clinical and biopsy findings were used in all cases for diagnosis. A diagnosis was confirmed by a positive biopsy specimen culture in 19 (43.2%) of 44 cases, and histopathological findings were compatible with the results of these cultures in all cases. All patients were treated with antituberculous chemotherapy, and the diseases in only two (4.5%) was resistant to the regimen. An independent observer assessed the clinical and imaging findings after a mean follow-up duration of 40 months. Forty-two (95.4%) of the 44 patients were successfully treated with conservative medical management and attained acceptable spinal deformity angles, and none of these patients had any residual instability, radiculopathy, or neurological compromise. Only 4.5% of the patients experienced residual spine deformity (as much as a 30 degrees kyphotic angle), which was clinically obvious but biomechanically stable.

CONCLUSIONS

Patients with Pott disease in the lumbar or thoracic region, without neurological deficits or kyphosis, can be treated conservatively in the vast majority of cases. Indications for surgery need to be redefined given these new data.

Imaging of infectious spinal disorders in children and adults

The aim of this review article is to outline the imaging of infectious disorders of the spine in adults and children. The clinical presentation, potential routes of infection and the pathogens commonly identified are discussed. The value of different imaging modalities in the diagnosis of spinal infection is presented including radiographic, CT, MR imaging and Nuclear Medicine including PET. The use of image guided techniques for diagnosis and subsequent treatment is briefly covered. The major differential diagnoses of infectious disorders of the spine are identified and contrasted with the typical findings in infection. The use of follow up imaging is evaluated.

General principles in the medical and surgical management of spinal infections: a multidisciplinary approach

OBJECT

Infections along the spinal axis are characterized by an insidious onset, and the resulting delays in diagnosis are associated with serious neurological consequences and even death. Infections of the spine can affect the vertebral bodies, intervertebral discs, spinal canal, and surrounding soft tissues. Neurological dysfunction occurs when the spinal cord becomes compressed, edematous, or ischemic due to compression by abscess or vascular compromise. The aim of this paper was to detail general diagnostic and management principles for this disease.

METHODS

Recent progress in medical technologies, including the development of potent antimicrobial drugs, advanced imaging, and improved surgical methods, have dramatically reduced morbidity and mortality rates for spinal infections; however, debate still exists on the proper management of this disease. In this paper, the authors review the current management protocols for spinal infections at their institution, focusing on medical and surgical treatments for vertebral osteomyelitis, intervertebral disc space infections, and spinal canal and soft-tissue abscesses.

CONCLUSIONS

Technological advances in imaging modalities, pharmaceutics, and surgery have resulted in excellent outcomes and have greatly reduced the morbidity and mortality rates associated with spinal infections. Currently, treatment of spinal infections requires a multidisciplinary team that includes infectious diseases experts, neuroradiologists, and spine surgeons. The key to successful management of spinal infections is early detection.

Vertebral osteomyelitis without disc involvement

Vertebral osteomyelitis is most commonly due to pyogenic or granulomatous infection and typically results in the combined involvement of the intervertebral disc and adjacent vertebral bodies. Non-infective causes include the related conditions of chronic recurrent multifocal osteomyelitis (CRMO) and SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) syndrome. Occasionally, these conditions may present purely within the vertebral body, resulting in various combinations of vertebral marrow oedema and sclerosis, destructive lesions of the vertebral body and pathological vertebral collapse, thus mimicking neoplastic disease. This review illustrates the imaging features of vertebral osteomyelitis without disc involvement, with emphasis on magnetic resonance imaging (MRI) findings.

[Sub occipital Pott's disease: report of 8 cases]

Craniocervical Pott's disease remains exceptional, and may cause spinal instability and severe cervicomedullary complications. We report eight cases of tuberculous spondylodiscitis at the craniocervical junction revealed by signs of spinal cord compression, torticollis and dysphagia. The value of CT and MR imaging is discussed.

Multifocal Pott's disease (tuberculous spondylitis) incidentally detected on Tc-99m MDP bone and Ga-67 citrate scintigraphy in a patient with diabetes

Pott's disease is an uncommon extrapulmonary form of tuberculosis. Delay in diagnosis and management may cause serious complications. The authors describe Pott's disease incidentally detected on Tc-99m MDP bone and Ga-67 imaging in a patient with diabetes. Tc-99m MDP bone scintigraphy showed intensely increased uptake in the lower cervical spine and lumbosacral regions. Ga-67 scintigraphy revealed intensely increased uptake corresponding to the areas noted on Tc-99m MDP bone scintigraphy. Magnetic resonance imaging showed destructive lesions in the C5-C6 and L5-S1 intervertebral discs with destruction of adjacent end plates. Biopsy of the lumbosacral area was guided by computed tomography, and histologic examination of the bone specimen showed caseation, giant cells, and acid-fast bacilli. Posterior decompression and posterolateral spinal fusion with bone grafts were performed. Antituberculous chemotherapy with isoniazid, rifampicin, pyrazinamide, and ethambutol was started. The patient showed remarkable relief of symptoms during a period of 9 months of therapy. Both Tc-99m MDP bone and Ga-67 imaging can offer the convenience of screening the entire body to detect multiple sites of Pott's disease.

Image-guided percutaneous drainage of tuberculous iliopsoas and spondylodiskitic abscesses: midterm results

PURPOSE

To evaluate midterm results of percutaneous drainage (PD) with image guidance in 21 patients with tuberculous iliopsoas abscesses with or without spondylodiskitis.

MATERIALS AND METHODS

Computed tomography (CT)-guided PD was performed in 21 patients with 26 tuberculous iliopsoas abscesses. Nineteen patients had bone involvement of two or more vertebrae. Eleven patients with spondylodiskitis had intradiskal abscesses. Five patients had bilateral psoas abscesses. Easily and safely accessible well-circumscribed abscesses larger than 3 cm were selected for PD. Catheters were inserted into the abscess cavities with Seldinger technique in all cases. In conjunction with PD, all patients had antituberculous drug therapy and underwent clinical and imaging follow-up for at least 1 year.

RESULTS

Percutaneous catheter placement was successful in all cases without procedural complications. On the basis of CT findings, complete evacuation of all abscesses was achieved initially. During follow-up, six (29%) of 21 patients had recurrences within 1 and 3 months after catheter removal. A total of 37 catheters were used; eight of the 37 catheters were inserted due to recurrences. Four patients needed two PD procedures, and two patients needed three due to recurrences. Four catheters were changed because of obstruction or dislocation. Drainage duration ranged from 5 to 36 days (mean, 14.9 days). The follow-up period was 12-52 months (mean, 24 months). None of the patients, including those with recurrence, required surgical drainage and débridement due to insufficient PD.

CONCLUSION

Image-guided PD in conjunction with antituberculous drug therapy is an effective and safe procedure in the treatment of tuberculous iliopsoas abscesses with or without spondylodiskitis.

Thoracic sequelae and complications of tuberculosis

Pulmonary tuberculosis is caused by Mycobacterium tuberculosis when droplet nuclei laden with bacilli are inhaled. In accordance with the virulence of the organism and the defenses of the host, tuberculosis can occur in the lungs and in extrapulmonary organs. A variety of sequelae and complications can occur in the pulmonary and extrapulmonary portions of the thorax in treated or untreated patients. These can be categorized as follows: (a) parenchymal lesions, which include tuberculoma, thin-walled cavity, cicatrization, end-stage lung destruction, aspergilloma, and bronchogenic carcinoma; (b) airway lesions, which include bronchiectasis, tracheobronchial stenosis, and broncholithiasis; (c) vascular lesions, which include pulmonary or bronchial arteritis and thrombosis, bronchial artery dilatation, and Rasmussen aneurysm; (d) mediastinal lesions, which include lymph node calcification and extranodal extension, esophagomediastinal or esophagobronchial fistula, constrictive pericarditis, and fibrosing mediastinitis; (e) pleural lesions, which include chronic empyema, fibrothorax, bronchopleural fistula, and pneumothorax; and (f) chest wall lesions, which include rib tuberculosis, tuberculous spondylitis, and malignancy associated with chronic empyema. These varieties of radiologic manifestations can mimic other disease entities. Therefore, recognition and understanding of the radiologic manifestations of the thoracic sequelae and complications of tuberculosis are important to facilitate diagnosis.

Tuberculosis from head to toe

Tuberculosis can affect virtually any organ system in the body and can be devastating if left untreated. The increasing prevalence of tuberculosis in both immunocompetent and immunocompromised individuals in recent years makes this disease a topic of universal concern. Because tuberculosis demonstrates a variety of clinical and radiologic findings and has a known propensity for dissemination from its primary site, it can mimic numerous other disease entities. Primary pulmonary tuberculosis typically manifests radiologically as parenchymal disease, lymphadenopathy, pleural effusion, miliary disease, or lobar or segmental atelectasis. In postprimary tuberculosis, the earliest radiologic finding is the development of patchy, ill-defined segmental consolidation. Both computed tomography (CT) and magnetic resonance (MR) imaging are helpful in diagnosing tuberculous spondylitis and tuberculous arthritis. CT is especially useful in depicting gastrointestinal and genitourinary tuberculosis. In tuberculosis involving the central nervous system, CT and MR imaging findings vary depending on the stage of disease and the character of the lesion. A high degree of clinical suspicion and familiarity with the various radiologic manifestations of tuberculosis allow early diagnosis and timely initiation of appropriate therapy, thereby reducing patient morbidity.

Spinal tuberculosis in adults. A study of 103 cases in a developed country, 1980-1994

Spinal tuberculosis (TB) accounts for about 2% of all cases of TB. New methods of diagnosis such as magnetic resonance imaging (MRI) or percutaneous needle biopsy have emerged. Two distinct patterns of spinal TB can be identified, the classic form, called spondylodiscitis (SPD) in this article, and an increasingly common atypical form characterized by spondylitis without disk involvement (SPwD). We conducted a retrospective study of patients with spinal TB managed in the area of Paris, France, between 1980 and 1994 with the goal of defining the characteristics of spinal TB and comparing SPD to SPwD. The 103 consecutive patients included in our study had TB confirmed by bacteriologic and/or histologic studies of specimens from spinal or paraspinal lesions (93 patients) or from extraspinal skeletal lesions (10 patients). Sixty-eight percent of patients were foreign-born subjects from developing countries. None of our patients was HIV-positive. SPD accounted for 48% of cases and SPwD for 52%. Patients with SPwD were younger and more likely to be foreign-born and to have multiple skeletal TB lesions. Neurologic manifestations were observed in 50% of patients, with no differences between the SPD and SPwD groups. Of the 44 patients investigated by MRI, 6 had normal plain radiographs; MRI was consistently positive and demonstrated epidural involvement in 77% of cases. Bacteriologic and histologic yields were similar for surgical biopsy (n = 16) and for percutaneous needle aspiration and/or biopsy (n = 77). Cultures for Mycobacterium tuberculosis were positive in 83% of patients, and no strains were resistant to rifampin. Median duration of antituberculous chemotherapy was 14 months. Surgical treatment was performed in 24% of patients. There were 2 TB-related deaths. Our data suggest that SPwD may now be the most common pattern of spinal TB in foreign-born subjects in industrialized countries. The reasons for this remain to be elucidated.