Diagnostic value of sacroiliac joint scintigraphy with 99m technetium pyrophosphate in sacroiliitis

Limited Diagnostic Value of Unilateral Sacroiliitis in Scintigraphy in Assessing Axial Spondyloarthritis

Objective.

To assess the diagnostic value for axial spondyloarthritis (SpA) of unilateral sacroiliitis in scintigraphy in daily clinical practice.

Methods.

In 207 patients with chronic back pain, the diagnostic value of scintigraphy was assessed retrospectively. The diagnosis made by the rheumatologist (axial SpA vs no axial SpA) was the standard.

Results.

Sensitivities of scintigraphy for any (unilateral or bilateral), bilateral, and isolated unilateral sacroiliitis were 64.9%, 40.2%, and 24.7%, respectively. Respective specificities were 50.5%, 57.7%, and 92.8%, resulting in likelihood ratios of 1.3, 1.0, and 3.4.

Conclusion.

Scintigraphy of the sacroiliac joints is of limited value for the diagnosis of axial SpA. Unilateral compared to bilateral sacroiliitis is slightly superior, but is associated with a low sensitivity.

The radiology of early arthritis

Accurate diagnosis of early arthritis is important because successful treatment with preservation of joint structure and function is most likely when specific therapeutic interventions are instituted early in the disease. Early arthritis may be difficult to accurately diagnose clinically, even for experience practitioners. High-yield radiologic studies are possible, but the radiologist must realize that for each patient and each disease, how and where to look, and what to look for, may differ. Conventional radiographs remain the most important screening studies for both the axial and appendicular skeleton. Other modalities, especially MRI, have limitations but can be powerful tools in problem cases. Each disease has target areas of early involvement that may differ from the classic distribution seen once the process is established. A careful examination of these areas for subtle but characteristic early findings will often be rewarding.

Asymptomatic sacroiliitis in inflammatory bowel disease. Assessment by computed tomography

Plain film radiographs and computed tomography scans of sacroiliac joints in 65 asymptomatic patients with known inflammatory bowel disease were performed and evaluated by two radiologists. Computed tomography revealed the presence of asymptomatic sacroiliitis in 21 (32%) of the 65 patients (New York grades 2 to 4); asymptomatic sacroiliitis was identified by plain film radiography in only 10 (18%) of 57 patients (p < 0.001). No correlation was observed between the presence or absence of sacroiliitis, and the age and sex of patients, disease type, or duration of disease. The prevalence and diagnostic value of computed tomography in the detection of asymptomatic sacroiliitis in patients with inflammatory bowel disease are discussed.

Comparison of bone scan, computed tomography, and magnetic resonance imaging in the diagnosis of active sacroiliitis

Quantitative bone scan (QBS), computed tomography (CT), and magnetic resonance imaging (MRI) have each been used to confirm the diagnosis of active sacroiliitis (SI) in patients with low back pain (LBP). The authors prospectively evaluated 19 patients referred for symptoms of possible inflammatory LBP (group I), 26 seronegative spondyloarthropathy (SNSP) patients with LBP (group II, inflammatory or mechanical), and 5 SNSP patients without LBP (group III) to determine which radiological scan alone or in combination with other serological tests (Westergren erythrocyte sedimentation rate, C-reactive protein, HLA-B27, immunoglobulin A) was most useful in confirming a clinical diagnosis of active inflammatory SI. All patients were followed up for a minimum of 1 year to confirm the clinical diagnosis and evaluate response to therapy. Eight of 19 group I patients had active SI clinically or on plain radiographs on follow-up evaluation. Of these patients, 5 had abnormal QBS (71%), 3 had abnormal CT scans (38%), and 8 had abnormal MRI scans (100%, type I lesions). These type I MRI lesions were indicative of active inflammation manifested as subcortical bone marrow edema. The remaining 11 group I patients had negative scans for SI. Ten of 26 group II patients with LBP had SI diagnosed clinically and confirmed with positive QBS (60%), CT (100%), and MRI (100%, type I lesions). The remaining 16 group II patients had mechanical LBP without active SI clinically and had negative QBS (88%), CT (19%), and MRI (100%, normal or type II lesions). These type II MRI lesions represented old postinflammatory lesions with either fibrosis or fat replacement. All 5 group III patients had negative scans for active SI. Three patients (2 group I and group II) with inflammatory SI treated with sulfasalazine showed marked improvement on serial MRI scans. Westergren erythrocyte sedimentation rate, C-reactive protein, immunoglobulin A, and CT scan alone or in combination with other tests were not reliable predictors of active SI. Positive QBS and HLA-B27 tests were the best combination of screening tests with 82% predictability of inflammatory SI in whites, and QBS alone had an 80% predictability in black patients. However, MRI, which had 100% predictability, was the best single test for confirming active inflammatory SI.

Investigation of joint disease

The role of nuclear medicine in the diagnosis and management of the major arthropathies is critically reviewed, with particular reference to osteoarthritis, rheumatoid and similar forms of arthritis, ankylosing spondylitis, non-specific back pain, gout, the neuropathic joint, avascular necrosis, infection and the consequences of prosthetic joint insertion. Attention is drawn both to practical applications and deficiencies in current techniques and knowledge.

Quantitative radio-isotope scanning in ankylosing spondylitis: a clinical, laboratory and computerised tomographic study

Quantitative sacroiliac and lumbar spine radio-isotope (Tc-99m MDP) scans were performed in 42 patients with ankylosing spondylitis, and repeated 12 months later in 25. Clinical and laboratory assessments as well as computerised tomographic (CT) scans of the sacroiliac joints (SIJ) and lateral lumbar spine x-rays, were performed. Bone (using the L3/4 area of the lumbar spine, sacrum, SIJ's and knee) to soft tissue (ST) ratios all correlated strongly with each other. Patients with high SIJ:ST ratios had significantly greater low-back stiffness (p less than 0.05). Change in serum IgA levels correlated negatively with change in bone: ST ratios. There was no relationship between bone: ST ratios and any other clinical or laboratory variables. The change in SIJ:ST ratios correlated positively with change in CT erosion score (p less than 0.05) and negatively with change in CT ankylosis score (p less than 0.05).

Evaluation of patients with back pain of suspected inflammatory nature

PURPOSE

Detection of early inflammatory back disease is often difficult. Certain clinical characteristics have been reported to increase the likelihood of its detection in referral patients, but the usefulness of these clinical characteristics has not been evaluated in an open population. In our study, we undertook to evaluate the value of the clinical history as a screening test for inflammatory back disease in a general population.

PATIENTS AND METHODS

Twenty-three male patients with back pain of moderate duration and with clinical characteristics suggestive of inflammatory back disease were recruited by advertising and were studied by various means, including computed tomography (CT), scintigraphy, and radiography.

RESULTS

One patient had radiographic sacroiliitis. Two had positive results for the B27 antigen, and another had positive results for the cross-reacting HLA antigen B7. Eight patients had abnormal scintiscans of the sacroiliac joints. Twenty-one of 23 patients and 20 of 23 control subjects had abnormalities that were detected by CT. Repeat plain radiographs of the pelvis done 36 months after enrollment into the study did not uncover further evidence of sacroiliitis.

CONCLUSIONS

These results indicate plain radiographic evidence of sacroiliitis will often not develop in patients with historical features suggestive of inflammatory back disease even with long-term evaluation, thus vitiating the specificity of these historical findings in men with back pain of relatively brief duration.

Effect of imaging time on the values of the sacroiliac index

Quantitative scintigraphy of the sacroiliac joints was performed in a group of normal subjects and a group of subjects with unilateral and bilateral sacroiliitis. The aim of the study was to determine whether the time intervals of imaging had any effect on the values of the sacroiliac index. Imaging was performed every 30 min up to 300 min and the indices were calculated at the time intervals mentioned. We found that the values of the sacroiliac index increased in the group of normal subjects until 150 min after the application of the radiopharmaceutical, and that in the group of subjects who had sacroiliitis they increased until 210 min. The results show that the time interval optimal to quantitative sacroiliac joint imaging is at least 3 1/2 h after administration of the radiopharmaceutical.

New criteria for the diagnosis of ankylosing spondylitis

Criteria for ankylosing spondylitis are useful for two main purposes. First, to provide unity of diagnosis in population surveys; secondly, in the field of therapeutic assessment. This paper is concerned with criteria used largely in the former role, i.e. as an epidemiological tool. Critical formulation and subsequent evaluation of criteria is important if a realistic measure of disease prevalence is to be obtained. The New York criteria have provided the general currency for diagnosis epidemiologically in recent years, but their value, in their originally published form, has been questioned for various reasons. Attempts have been made to improve these criteria or to suggest alternatives. Although increased sophistication of the original New York criteria has doubtless been achieved, the position regarding the diagnosis of ankylosing spondylitis continues to represent a challenge. The main concern is that the present "index of truth" for the disease, radiological sacroiliitis, is all too often a delayed feature, presenting only after pain has been present for some time. A second problem is the difficulty in diagnosing with confidence the early changes of sacroiliac sclerosis and erosion, and the degree of intra- and inter-observer error arising from these changes. Newer techniques such as radioisotope scintigraphy and computerised tomography (CT) are unlikely to replace the traditional pelvic radiograph. The way forward is more likely to be in the direction of how existing data are processed rather than what is used to obtain them. In this vein, suitable mathematical/biological models coupled with computer technology could provide realistic tools through a system of probability weighting of existing criteria.

Radiological and scintigraphic findings in patients with a clinical history of chronic inflammatory back pain

The prevalence of radiological abnormalities of the sacroiliac joints, the manubriosternal joint, and the lumbar spine were assessed, and quantitative sacroiliac scintigraphy was performed in 151 patients with a history of chronic inflammatory back pain and in 31 controls with non-inflammatory back pain. Sacroiliitis was found in 124 patients (82%), manubriosternal lesions in 84 patients (56%), and lesions of the lumbar spine in 58 patients (38%). In 19 patients (13%), manubriosternal lesions provided the sole radiological abnormality and in five patients (3%) no radiological abnormality could be demonstrated at any of these sites. Quantitative sacroiliac scintigraphy showed increased values in 69 of 137 patients examined (50%), but also in 10 out of 12 control patients with disc degeneration (83%) and is, therefore, nonspecific for inflammatory lesions. Radiological examination of the manubriosternal joint is recommended in patients with inflammatory back pain without radiographic evidence of sacroiliitis.

Quantitative sacroiliac scintiscanning: a sensitive and objective method for assessing efficacy of nonsteroidal, anti-inflammatory drugs in patients with sacroiliitis

Serial computer assisted quantitative sacroiliac scintiscanning (SI joint/sacrum ratios) 3 hours after low dosage (5 mCi) 99mTc methylene diphosphonate has been used as an objective index of sacroiliitis in a single blind 14-day cross-over comparison of azapropazone 600 mg b.d. and naproxen 500 mg b.d. in 18 patients with active sacroiliitis. Clinical assessments included visual analogue scales for measurement of pain and early morning stiffness, chest expansion, a modified Schober test, and goniometric measurement of thoracolumbar spinal flexion by means of an inclinometer. Statistically significant decreases in pain (p less than 0.001) and early morning stiffness (p less than 0.001) followed treatment with each NSAID, but there was no significant difference in the fall in these parameters, although 15 out of 18 patients expressed a preference for naproxen. Chest expansion and thoracolumbar flexion were not significantly affected by either drug. Serial quantitative scintigraphy showed a mean fall in joint sacrum ratios following each treatment which was statistically significant (p less than 0.02) only after naproxen. Serial quantitative scintigraphy can be used as an objective method of assessing sacroiliitis and was sufficiently sensitive to reflect the patients' subjective preference in a short-term comparison of 2 NSAID.

Evaluation of quantitative sacroiliac scintigraphy for the early detection of sacroiliitis

Quantitative sacroiliac scintigraphy (QSS) was evaluated for the detection of sacroiliac (SI) joint disease before the appearance of radiographic/changes. QSS with fractional quantitation was done in 13 age- and sex-matched controls and 28 patients with different grades of radiographic sacroiliitis. The SI index of each joint was considered separately. The mean SI index values in patients with grade I radiographic sacroiliitis (1.54) and HLA-B27 positive patients with low back pain (1.50) were significantly (P less than 0.01) higher than the mean SI index of controls (1.22); but more than 50% of their SI index values were within the 97.5% confidence limits of the control range. The mean SI index values of patients with grade II (1.38) and grade III (1.34) radiographic sacroiliitis did not differ significantly from the mean SI index of controls (P greater than 0.05). Thus a large overlap between the normal and abnormal ranges of sacroiliac ratios limits the utility of quantitative sacroiliac scintigraphy for the early diagnosis of sacroiliac joint disease.

The value of quantitative sacroiliac scintigraphy in detection of sacroiliitis

To evaluate clinical usefulness of quantitative sacroiliac scintigraphy (QSS) in detecting sacroiliitis, we used a modified, pixel by pixel technique for calculating sacroiliac joint/sacrum uptake ratios (sacroiliac joint index - SII). We studied 90 controls, 18 selected patients with active sacroiliitis, 2 ankylosing spondylitis patients with completely ankylosed sacroiliac joints, 14 patients with nonspecific low back pain and 5 patients with rheumatoid arthritis. In the controls, we found that the SII decreases with increasing age (P less than 0.001) and is higher in males than in females (P less than 0.005). In the patients with active sacroiliitis, 9 out of 14 older than 30 had an abnormal SII; 3 of these patients showed no radiographic or CT abnormalities of the sacroiliac joints. None of the 4 patients with sacroiliitis under 30 years of age had values which fell out of the normal range for their age and sex. Only 1 of the 14 patients with non-inflammatory low back pain had an abnormally high SII. A borderline SII was found in 1 of the 5 patients with rheumatoid arthritis. QSS may be useful in detecting active sacroiliitis, sometimes even before the occurrence of radiologic abnormalities. However, because of its low sensitivity, its clinical usefulness is limited, especially in patients under 30 years of age.

The diagnostic value of bone scintigraphy in patients with low back pain

Bone scintigraphy has been studied in two groups of patients presenting with low back pain. In one group of 38 patients suffering "nonspecific" back pain, bone scintigraphy and laboratory findings were negative in 24. There were abnormal laboratory findings in all of the remaining 14 and 7 had positive bone scans indicative of clinically significant disease. Selection of patients for bone scintigraphy in this group should therefore be influenced by abnormal laboratory findings and elevation of the erythrocyte sedimentation rate in particular. By comparison, the bone scans were reviewed from another group of patients suffering previously known malignancy. Out of 138 patients, nearly 40% showed a positive bone scan due to subsequently proven metastasis. Bone scintigraphy was positive in a further 14% as a result of osteoporotic rib fracture and vertebral body collapse. In half of these, it was not possible to exclude malignancy by scintigraphy. The present findings indicate that bone scintigraphy is not a useful procedure in patients with long-standing low back pain who have normal radiographs and normal laboratory findings.

The radiographic diagnosis of sacroiliitis. A comparison of different views with computed tomograms of the sacroiliac joint

Conventional radiography is the standard method of objectively identifying sacroiliitis. Single views of the sacroiliac joints can be unequivocally interpreted in 70-80% of patients with low back pain. A series of views usually correctly resolves the ambiguity in the remaining 20-30% of patients (67% correct). Computed tomography will be helpful in the few patients in whom a series of views produces equivocal interpretation.

Sacroiliac joint uptake ratios in inflammatory bowel disease: relationship to back pain and to activity of bowel disease

Sacroiliac uptake ratios based on 99Tcm methylene diphosphonate images were calculated in 14 patients with ankylosing spondylitis, 23 patients with non-specific backache, 33 patients with inflammatory bowel disease (ulcerative colitis 19, Crohn's disease 14) and 33 control subjects. Twenty-eight of the control subjects were patients referred from a breast cancer clinic. In the control subjects, and in 20 patients with inflammatory bowel disease who did not have back pain, sacroiliac ratios decreased significantly with increasing age (p less than 0.001 and p less than 0.01 respectively). Sacroiliac uptake ratios were significantly higher in ankylosing spondylitis than in patients with non-specific backache. Seven of the 14 patients with ankylosing spondylitis had higher sacroiliac ratios than any recorded in the control subjects. Eleven patients with inflammatory bowel disease had abnormally high sacroiliac uptake ratios; ten of these patients had back pain. Increased sacroiliac joint uptake in such patients may reflect early sacroiliitis. No relationship was detected between sacroiliac uptake and the activity of the bowel disease. Sacroiliac uptake ratios were significantly higher in the inflammatory bowel disease patients suffering from back pain than in age and sex matched patients with (a) inflammatory bowel disease but no back pain or (b) non-specific backache.

Quantitative sacro-iliac scintigraphy. I. Methodological aspects

Methodological aspects of quantitative sacroiliac scintigraphy (QSS) using [99mmTc]methylene diphosphonate (MDP) were studied. To improve the diagnostic value of QSS it is important to understand the errors involved in the calculated indices. The accumulated radioactivity in the sacro-iliac joint, compared with that in the sacral bone (SI ratio), decreased linearly with age, by about 24% from the age of 15 years to 71 years. The post-injection time of scintigraphy was not critical, if the scintigraphy was carried out after 2.5 hours. Although the variances of the SI ratios in our control material were relatively high, the repeatability of the SI ratio measurement was 3.9%. The influence of measuring geometry on the QSS and the acceptability of the sacrum as the reference area were tested.

Arthritis in psoriasis

A group of 61 unselected patients with psoriasis attending a dermatology clinic were studied to determine the prevalence of psoriatic arthritis. On defined criteria arthritis was present in 41.6%. Peripheral arthritis was present in 15.5%, and sacroiliitis in 43%. A strong association of distal interphalangeal arthritis with psoriasis and nail dystrophy was confirmed. Tissue typing showed a strong association of B23, 17, in Caucasoid psoriatics, while the haplotype A1/B8 was increased in mixed Caucasoid--Negroid psoriatics.

An improved method for sacro-iliac joint imaging: a study of normal subjects, patients with sacro-iliitis and patients with low back pain

A new method is described for quantitative measurement of the uptake of 99mTc--methylene diphosphonate (MDP) by the sacro-iliac joints. The method uses 'regions of interest' providing advantages over the previously described 'slice' method; the two methods are compared in normal subjects, patients with known sacro-iliitis and patients with low back pain. Sacro-iliac activity, as calculated by the sacro-iliac index (SII) in normal patients, was shown to decrease with age in females but not in males. The SII was compared with radiographs of the sacro-iliac joints in the patients with known sacro-iliac joint disease and in those with low back pain. The method is useful for the exclusion of sacro-iliitis as a specific cause of back pain.

Prospective evaluation of sacroiliac scintigraphy in chronic inflammatory back pain

To assess the usefulness in screening for sacroiliitis of a wide band profile cut which included the entire sacroiliac (SI) joint, 34 patients with chronic inflammatory back pain (IBP) underwent sacroiliac joint scintigraphy with 99mTc-methylene diphosphonate while receiving no antiinflammatory therapy. The sacroiliac joint to sacrum (SIJ/S) ratios in those with back pain differed significantly from the ratios of an age-matched control group. However, 12 of the 34 patients with inflammatory back pain had normal or equivocal sacroiliac radiographs and 4 of 12 had normal SIJ/S ratios. All 4 were HLA-B27 positive, had diminished lumbar movement, and required antiinflammatory medication; 2 had diminished chest expansion; 1 has developed iritis. We conclude that this technique is not a reliable screening procedure. Therapy with antiinflammatory drugs was associated with a significant decrease in the SIJ/S ratios in 19 of the 34 who were reimaged.

Bone scanning in lumbar disc herniation

99m technetium methylene diphosphate was used for whole body scanning and linear multiplane tomoscanning in 10 patients with typical clinical symptoms of prolapsed disc, in order to investigate whether there would be an increased focal accumulation corresponding to the bone structures adjacent to the affected disc. The diagnosis of a prolapsed disc was confined by amipaque myelography, carried out in 9 patients, and finally verified at operation. In none of the 10 cases could accumulation of radioactivity in the bony structures of the affected lumar segment be demonstrated. Consequently this method has not been adopted for the diagnosis of prolapsed lumbar discs. However it was demonstrated that 99m technetium methylene diphosphate scintillography is useful in the differential diagnosis of anchylosing spondylitis and discitis.

Pyogenic sacroiliitis

Seven definite and three probable cases of pyogenic sacroiliitis are presented and compared to 72 cases found in the English literature. Patients may present with a subacute localized or an acute systemic illness. Six of our patients were parenteral drug abusers. Symptoms often were vague, but sacroiliac tenderness was invariably found on examination. Sacroiliac uptake of gallium67 citrate and/or technetium99m pyrophosphate suggested the diagnosis which was confirmed by fluoroscopically controlled joint aspiration when blood cultures were sterile. Gram-negative organisms, group B streptococci and a Staphylococcus were isolated. Antibiotic treatment for four to six weeks was uniformly successful. Surgery should be reserved for abscess or sequestrum formation, neither of which were encountered in this series.

Quantitative sacroiliac joint scintigraphy. A critical assessment

With quantitative sacroiliac joint scintigraphy (QSS), sacroiliac joint-to-sacrum (SIS) ratios greater than or equal to 1.40 are abnormal for our method. High SIS ratios are associated with roentgenographically appreciated sacroiliitis and with early clinically evident sacroiliitis. Although highly sensitive, QSS abnormalities are not specific for inflammatory sacroiliac (SI) joint disease. High SIS ratios are also seen in rheumatoid arthritis, degenerative abnormalities of the lumbosacral spine, and metabolic bone disorder. Other disorders with roentgenographic SI joint abnormalities must be studied scintigraphically before QSS can be employed as a useful diagnostic test.