Importance of Conventional Radiography in the Diagnosis of Diffuse Idiopathic Skeletal Hyperostosis in the Diagnosis of

studies - ABSTRACT Background: Diffuse Idiopathic Skeletal Hyperostosis (DISH) is a widespread disease among the elderly population worldwide. Skeletal imaging is essential for the diagnosis of the disease and the complications that occur. Of these, Conventional Radiography (CR) is most commonly used due to the occurrence of characteristic changes of diagnostic significance and the low cost of the examination compared to Computed Tomography and (CT) and magnetic nuclear tomography (MRI). The Aim: The aim of the study was to analyze the results established by CR and their correlation with biochemical results in patients with diffuse idiopathic skeletal hyperostosis. Materials and Methods: The results of the CR of the axial and peripheral skeleton in 225 patients with DISH, who meet the classification criteria of Resnick et Niwayama and the Mata-score system, are analyzed. The patients were treated at the Rheumatology Clinic of “St. George” University Hospital, Plovdiv and the “St. George” Rheumatology Diagnostic Center. The radiographs were analyzed by two independent radiologists and the results were completed in specially made slips. The biochemical parameters were studied in the Central Laboratory, University Hospital “St. George”, Plovdiv. The statistical processing was carried out through the statistical program SPSS ver 24. Results: Comparison of the Resnick et Niwayama criteria with the Mata-score system shows that the former criteria are significantly less sensitive and the use of the latter is recommended in routine rheumatology practice (p <0.01). A significant correlation was found between Mata-score in patients with DISH with the age of patients, the duration of complaints, Visual analog scale for pain assessment by the patient, elevated serum blood sugar levels, glycated hemoglobin, C-peptide, uric acid, total cholesterol and triglycerides (p <0.001). Conclusion: Our results described in detail the findings found in patients with Diffuse Idiopathic Skeletal Hyperostosis and demonstrated the benefits of using Mata-criteria in the diagnosis of DISH. Significant correlations were found between CR results and biochemical data. We recommend that rheumatologists use Mata-criteria in routine clinical practice to diagnose DISH.

axial tomography (CT) and magnetic Resonance Imaging (MRI) are essential for diagnosis, complications and the distinction of DISH from other related diseases [10][11][12]. Of these, CR is most commonly used due to the occurrence of characteristic radiological changes in the axial and peripheral skeleton. Some authors consider that "Chest radiograph is a gold screening test for diagnosing DISH" [2,13,14]. Resnick et Nivayama, 1976, described the changes found by CR in patients with DISH and demonstrated that the disease is not limited to the spine [15]. In subsequent years, these findings were confirmed by other authors [16][17][18][19][20][21]. The authors note that changes initially occur in the lower right thoracic segment (around Th 9,8,7,10). Slight fine calcification of the cortex of the anterolateral surface of the vertebrae is observed, with the newly formed bone having a linear shape and uneven contours [15]. Later, The interdiscal space (especially at the onset of the disease) is completely preserved, and the apophyseal and sacroiliac joints are not altered [22,23].
Radiographic changes can be found at all sites of the peripheral skeleton and the soft tissues around it [20,21]. In the peripheral skeleton hyperostoses are observed especially on the diaphysis, tubers, trochanters, ossification of the ribs and pelvis, and in the soft tissues thickening, calcification or ossification and irregularities.
In the field of entheses (especially in the pelvis) these changes are more pronounced, often in the form of a small broom (whistering ossification) [15,[24][25][26]. A significant problem in patients with DISH is that the diagnosis is made when there are already various manifestations such as fractures, a consequence of minimal trauma, back pain, non-response to treatment, dysphagia and dyspnea, the appearance of pseudoarthrosis [27][28][29][30][31][32], neurological and orthopedic complications of abrupt movement of the spine, which is not clear what disease they are associated with [33][34][35].
The currently used diagnostic criteria for DISH are from the last century. They are based on radiological changes mainly of the spine: criteria of Julkunen, et al. [36], criteria of Resnick et Niwayama [15], criteria of Utsinger, 1985 [37,38]. These radiological criteria are visible only 10-15 years after the onset of the disease and cannot be used for early diagnosis [32], so it is recommended to look for new, more modern ones [2]. In the routine rheumatologists practice, the criteria of Resnick et Niwayama [15] are most often used.
According to Julkunen, et al. [36], the diagnosis of DISH can be confirmed by the presence of bridges connecting between two or three vertebral bodies, at least at two sites of the thoracic spine [36]. Utsinger, et al. [38], held that the diagnosis of DISH could be made by involving three consecutive thoracic vertebral bodies in the disease process, to which should be added the presence of peripheral enthesopathies [36]. According to Mata and co-authors, Mata's score 1-3 is assumed that the patient has initial changes for DISH, 4-6 is considered a moderate form and more than 7 -a severe form of the disease [39,40]. Mader, et al. [2] recommend that all researchers be "encouraged" to seek new diagnostic criteria for DISH that include constitutional, demographic, and metabolic factors.

The Aim
The aim of the study was to analyze the results established by CR, as well as the results of the assessment of Mata score in patients with DISH from the Bulgarian population.

Materials and Methods
The results of the CR of the axial and peripheral skeleton in 425 patients with DISH, are analyzed. The patients were treated at the Rheumatology Clinic of "St. George" University Hospital, Plovdiv and the "St. George" Rheumatology Diagnostic Center, Bulgaria.
The radiographs were analyzed by two independent radiologists and the results were completed in specially made slips. The biochemical parameters were studied in the Central Laboratory, University Hospital "St. George", Plovdiv. The control group included 150 patients, healthy individuals, without complaints of pain and stiffness in the musculoskeletal system, similar in sex and age to the monitored group of patients who visited the University Clinic of Rheumatology "St. George", Plovdiv, after being invited by researchers through general practitioners. The control group has no diseases and does not accept therapy. The statistical processing was carried out through the statistical program SPSS ver 24.
Including criteria for patients in the study: a.
Age over 18 years.  e. Statistical data processing by computer program. SPSS ver 24.

CR Examination
The CR examination were taken at the Department of Radiology, Medical University, Plovdiv, using a conventional digital CR machine with the possibility of scopic and graphic examinations.

All CR imaging tests comply with the national standard in Imaging
Diagnostics and have minimal radiation exposure for the patient.
A Siemens AXIOM Iconos R200 digital Japanese CR machine, a CR system for universal use in hospitals, a system for digitization of conventional CR and disk recording were used. The CR examination were analyzed sequentially by two radiologists and were According to Julkunen, et al. [36], the diagnosis of DISH can be confirmed by the presence of bridges connecting between two or three vertebral bodies, at least at two sites of the thoracic spine [36].
The Mata's score (1998) is defined as: a.
In the absence of ossification, b.
In ossification without bone bridges, c.
Ossification and incomplete bone bridges, d.
In ossification with full bridges e.
In severe ossification with increasing width of the bridges [39].
In the peripheral skeleton, the presence of enthesitis

Patients
The study of the demographic indicators of the patients are presented in Table 1.   score. The next visits were every 2 years and CR was also performed.

Results
The radiographs were re-evaluated to Mata's score and the results are presented in Table 3. Note: *ALL -anterior longitudinal ligament **PLL -posterior longitudinal ligament ***Dual-energy X-ray absorptiometry  (Table 3). Correlation between CR results in patients with DISH,

Mata's score, and biochemical parameters is by ANOVA-test and
Fischer coefficient (Table 4). Additional radiographs were taken in 118 patients with a history of peripheral skeletal complaints.
Characteristic changes were found (ossification of the edges,

Discussion
The clinical diagnosis at the onset of the disease of DISH is difficult and sometimes impossible due to the lack of typical symptoms of the disease and characteristic imaging changes [18,28,41]. The disease is suspected in patients over 50 years of age, men who complain of prolonged diffuse back pain, in the area of various entheses, tendons, joints, bone edges and tubers, in normal or slightly altered routine laboratory tests [1][2][3]. This suspicion is exacerbated by the establishment of muscle rigidity and restriction of movement around the pain region. Sometimes the disease is painless [5,12,42]  formation of new bone, prolonged, enlarged bone bridges of the cervical spine, thoracic spine or lumbar spine [2]. Other manifestations (thoracic pain, shoulder pain, provoked rotator cuff pain, BMI>30, diabetes mellitus, hypertension, obesity) were not significantly accepted as diagnostic criteria [2]. This raises the question for discussion -if only pronounced bone changes are relevant for the diagnosis of DISH, and this occurs in an advanced, late phase of the disease, it is of little benefit to the patient and their attending physicians could not prevent the disease. In our study, we used routine DISH imaging methods. The changes detected by the CR of the spine, peripheral skeleton and soft tissues around it in patients with DISH correspond to the data of the authors [3][4][5]24]. We found calcification and ossification of the ALL, preserved intervertebral spaces, no degenerative changes of the disc, hyperostosis changes of the vertebrae, preserved apophyseal, costovertebral and sacroiliac joints. These changes are best expressed in the thoracic region and not coincidentally Mata et al. note that "Chest radiograph" is a screening test for DISH. Early diagnosis (which can be made 10 years before the full development of the disease) helps to recommend preventive measures for the underdevelopment of the disease [2], which is the goal of rheumatologists.

Conclusion
Our results described in detail the findings found in patients with Diffuse Idiopathic Skeletal Hyperostosis and demonstrated the benefits of using Mata's score in the scoring of DISH. Significant correlations were found between CR results and biochemical data.
We recommend that rheumatologists use Mata's score in routine clinical practice to follow-up the patients.