Detection of sacro-ilitis. A comparison between profile scanning with the use of 99m Tc pertechnetate and scintigraphy with 99m Tc diphosphonate

Use of Imaging in Axial Spondyloarthritis for Diagnosis and Assessment of Disease Remission in the Year 2022

Medical imaging remains the cornerstone of diagnostics and follow-up of axial spondyloarthritis (axSpA) patients. With the lack of specific biomarkers allowing monitoring of disease activity and progression, clinicians refer to imaging modalities for accurate evaluation of the axSpA burden. Technological advances and increasing availability of modern imaging techniques such as MRI have enabled faster diagnosis of the disease, hence dramatically changed the diagnostic delay and improved the prognosis and functional outcomes for axSpA patients.Active sacroiliitis as visualized by MRI has been widely accepted as a diagnostic tool, and definitions of inflammatory and structural lesions within the axial skeleton have been developed. Recently, it has been acknowledged that bone marrow edema, suggestive of sacroiliitis, is a common finding among non-SpA patients, and could be attributed to mechanical loading or accumulate with age in healthy individuals. Therefore, it is crucial to distinguish between true pathological and concealing imaging findings, not only for diagnostic but also for disease remission purposes. New imaging modalities, aimed for in vivo visualization of specific molecular processes, could be employed to cross-validate findings from techniques used in daily clinical practice. This review critically evaluates the use of different imaging modalities for diagnosis and assessment of disease remission in axSpA in the year 2022.

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.

A combined method for quantitative pertechnetate scintigraphy in the diagnosis of sacroiliitis. A controlled study

A simplified scintigraphic technique for the assessment of sacroiliitis is described. It is based on the fact that an inflamed joint shows increased perfusion activity after administration of sodium pertechnetate. The sacroiliac joints are located by injection of a small amount of bone-seeking activity. Thereafter the pertechnetate activity is injected and the bone-seeking activity subtracted. The perfusion (pertechnetate) activity of the sacro-iliac joints is related to the activity of the large vessels of the thigh. Normal values have been established based on a study of 39 healthy controls. The method has been applied to 2 groups of patients with clinical sacroiliitis, one with and one without radiographical signs of sacroiliitis. The patients with radiographically verified sacroiliitis showed significantly higher values than the controls. The technique offers a high specificity and a high positive predictive value.

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.

The thermographic pattern of the lower back with special reference to the sacro-iliac joints in health and inflammation

The thermographic appearance of the sacro-iliac joints in health and in active inflammation has been established on the basis of 72 thermographic examinations of healthy volunteers and 82 examinations of patients with clinically and radiographically active disease. In the latter group a certain number of cases showed increased heat over the sacro-iliac joints. In addition to the heat patterns described, the main conclusion of the study is a certain variability of the normal thermal pattern, a basic experience of which is necessary for the optimal interpretation of a thermogram in suspected sacro-iliitis. Despite this variability, it is possible to recognize a standard heat pattern from which most heat patterns can be derived with more or less quantitative variations. One factor affecting the thermal pattern in a fairly constant way is the amount of subcutaneous fat.

A method for combined quantitative pertechnetate and bone scintigraphy of the sacro-iliac joints

A technique for combined quantitative bone and pertechnetate (perfusion) scintigraphy of the sacro-iliac joints is described. The method is based on localization of the joints in the image obtained after the injection of a small dose of bone-seeking technetiated methyldiphosphonate. This image is later subtracted from the image obtained after the injection of pertechnetate. This combination of methods is believed to constitute a more accurate way of localizing the sacro-iliac joints than the previously used method, based on fluoroscopy. A minor comparison between these two ways of localising the joints is reported too. It is possible that the combination of quantitative bone and pertechnetate scintigraphy will improve the overall sensitivity of the scintigraphic method.

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.

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.

Sacroiliitis in women--a late sequela to acute salpingitis

Fifty-seven women who were treated for severe acute salpingitis between June, 1974, and June, 1976, were examined in 1978, 24 to 48 months after their first hospitalization. At the same time, 31 healthy women matched for age and parity were examined. All patients and control subjects were examined independently by a gynecologist and a rheumatologist. Forty-two of the patients and all control subjects were examined by quantitative 99mTc-pertechnetate scanning of the sacroiliac joints. These same joints also were examined by x-ray in the 57 patients. Sacroiliitis was documented in 39 of the 57 salpingitis patients (68%) and in one of the control subjects (3%), a difference which was statistically significant. There was no difference between the two groups in the presence of histocompatibility antigen HLA B27. The findings strongly suggest a correlation between severe acute salpingitis and sacroiliitis in women.

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.

The reliability of quantitative bone scanning in sacro-iliitis

Arthritis of the sacro-iliac joints is a fairly common condition occurring either in isolation or as a part or pelvospondylitis. Because of the difficulty of establishing a diagnosis before X-ray changes have appeared, various radionuclide scanning techniques have been developed to make possible an early diagnosis. Opinions have differed as to the reliability of radionuclide methods using "bone seeking" radiopharmaceuticals. Patients with clinically and/or radiologically proven sacro-iliitis were imaged by means of 99m-Tc-EHDP. An S.I. index was calculated as the ratio of the maximum activity of the sacro-iliac joints to the minimum activity of the iliac wings. The accuracy of the method was very good, and it is recommended as a supplement to clinical examination and X-ray studies.

Quantitative 99mTc pertechnetate scanning of the sacro-iliac joints. A follow-up study of patients with suspected sacro-iliitis

Quantitative 99mTc pertechnetate sacro-iliac scanning (QTPS) was performed in 30 patients suspected of having sacro-iliac arthritis (SI). Abnormal scanning results but lack of definite radiographic changes were noted in all of them. Twenty-four of these patients were followed-up for an average of 3.4 years; roentgenological abnormalities were found in 23 patients, or 95%, namely definite SI in 13, slight abnormalities in 1 previously normal patient, inactive changes in 3, suspected SI was unchanged in the radiographs in 5 and regression of previously observed grad-I changes was found in 1. In only 1 patient was the radiological picture unchanged normal. No definite roentgenological SI developed in any of the 12 controls (patients with normal (QTPS) we followed in the same way. A close correlation was noted between the QTPS and the patients' complaints of low back pain/stiffness and the clinical findings, including the presence of HLA-B27. The present study confirms that, despite the absence of radiographic changes, QTPS allows identification of a group of clinical and laboratory features which together are sufficiently characteristic of SI to establish that diagnosis. QTPS also enables us to discover clinically silent SI.