Karl Erik Jensen

Magnetic resonance imaging-determined synovial membrane volume as a marker of disease activity and a predictor of progressive joint destruction in the wrists of patients with rheumatoid arthritis.

OBJECTIVE To evaluate the synovial membrane volume, determined by magnetic resonance imaging (MRI), as a marker of joint disease activity and a predictor of progressive joint destruction in rheumatoid arthritis (RA). METHODS Twenty-six patients with RA, randomized to receive disease-modifying antirheumatic drug (DMARD) therapy alone (11 patients) or DMARDs in combination with oral prednisolone (15 patients), were followed up for 1 year with contrast-enhanced MRI of the dominant wrist (months 0, 3, 6, and 12), conventional radiography (months 0 and 12), and clinical and biochemical examinations. Bone erosion (by MRI and radiography) and synovial membrane volumes (by MRI) were assessed. RESULTS Significant synovial membrane volume reductions were observed after 3 and 6 months in the DMARD + prednisolone group, and after 6 and 12 months in the DMARD-alone group (P < 0.01-0.02, by Wilcoxon-Pratt analysis). The rate of erosive progression on MRI was highly correlated with baseline scores and, particularly, with area under the curve (AUC) values of synovial membrane volume (Spearmans sigma = 0.69, P < 0.001), but not with baseline or AUC values of local or global clinical or biochemical parameters, or with prednisolone treatment. In none of 5 wrists with baseline volumes <5 cm3, but in 8 of 10 wrists with baseline volumes > or =10 cm3, erosive progression was found by MRI and/or radiography, indicating a predictive value of synovial membrane volumes. MRI was more sensitive than radiography for the detection of progressive bone destruction (22 versus 12 new bone erosions). CONCLUSION MRI-determined synovial membrane volumes are closely related to the rate of progressive joint destruction. Quantitative MRI assessment of synovitis may prove valuable as a marker of joint disease activity and a predictor of progressive joint destruction in RA.

Ultrasonography of the metacarpophalangeal and proximal interphalangeal joints in rheumatoid arthritis: a comparison with magnetic resonance imaging, conventional radiography and clinical examination.

Signs of inflammation and destruction in the finger joints are the principal features of rheumatoid arthritis (RA). There are few studies assessing the sensitivity and specificity of ultrasonography in detecting these signs. The objective of the present study was to investigate whether ultrasonography can provide information on signs of inflammation and destruction in RA finger joints that are not available with conventional radiography and clinical examination, and comparable to the information provided by magnetic resonance imaging (MRI). The second to fifth metacarpophalangeal and proximal interphalangeal joints of 40 RA patients and 20 control persons were assessed with ultrasonography, clinical examination, radiography and MRI. With MRI as the reference method, the sensitivity, specificity and accuracy of ultrasonography in detecting bone erosions in the finger joints were 0.59, 0.98 and 0.96, respectively; they were 0.42, 0.99 and 0.95 for radiography. The sensitivity, specificity and accuracy of ultrasonography, with signs of inflammation on T1-weighted MRI sequences as the reference method, were 0.70, 0.78 and 0.76, respectively; they were 0.40, 0.85 and 0.72 for the clinical examination. With MRI as the reference method, ultrasonography had higher sensitivity and accuracy in detecting signs of inflammation and destruction in RA finger joints than did clinical and radiographic examinations, without loss of specificity. This study shows that ultrasonography has the potential to improve assessment of patients with RA.

MRI quantification of rheumatoid arthritis: Current knowledge and future perspectives

The international consensus on treatment of rheumatoid arthritis (RA) involves early initiation of disease modifying anti-rheumatic drugs (DMARDs) for which a reliable identification of early disease is mandatory. Conventional radiography of the joints is considered the standard method for detecting and quantifying joint damage in RA. However, radiographs only show late disease manifestations as joint space narrowing and bone erosions, whereas it cannot detect synovitis and bone marrow oedema, i.e., inflammation in the synovium or the bone, which may be visualized by magnetic resonance imaging (MRI) months to years before erosions develop. Furthermore, MRI allows earlier visualization of bone erosions than radiography. In order to allow early treatment initiation and optimal guidance of the therapeutic strategy, there is a need for methods which are capable of early detection of inflammatory joint changes. In this review, we will discuss available data, advantages, limitations and potential future of MRI in RA.

Neuronal pH Regulation: Constant Normal Intracellular pH is Maintained in Brain during Low Extracellular pH Induced by Acetazolamide—31P NMR Study:

The intracellular pH in the brain was studied in six healthy volunteers before and immediately after the administration of 2 g of acetazolamide. Phosphorus-31 nuclear magnetic resonance spectroscopy by a 1.5 tesla whole-body scanner was used. The chemical shift between the inorganic phosphate and the phosphocreatine resonance frequencies was used for indirect assessment of the intracellular pH. The mean baseline intracellular pH was 7.05 ± 0.04 (SD). The mean pH changes obtained at 15-min intervals within the first hour of acetazolamide administration were −0.03 ± 0.04 (SD), −0.02 ± 0.03 (SD), and 0.00 ± 0.04 (SD), i.e., no statistically significant pH decrease was observed during the period where extracellular pH is known to drop markedly. Although several factors contribute to the lack of change of the intraneuronal pH, we will discuss that this observation in addition might suggest a direct intracerebral effect of acetazolamide.

Delayed Gadolinium-Enhanced Magnetic Resonance Imaging (dGEMRIC) of Hip Joint Cartilage: Better Cartilage Delineation after Intra-Articular than Intravenous Gadolinium Injection

Purpose: To investigate and compare delayed gadolinium (Gd-DTPA)-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) in the hip joint using intravenous (i.v.) or ultrasound-guided intra-articular (i.a.) Gd-DTPA injection. Material and Methods: In 10 patients (50% males, mean age 58 years) with clinical and radiographic hip osteoarthritis (OA; Kellgren score II–III), MRI of the hip was performed twice on a clinical 1.5T MR scanner: On day 1, before and 90–180 min after 0.3 mmol/kg body weight i.v. Gd-DTPA and, on day 8, 90–180 min after ultrasound-guided i.a. injection of a 4 mmol/l Gd-DTPA solution. Coronal STIR, coronal T1 fat-saturated spin-echo, and a cartilage-sensitive gradient-echo sequence (3D T1 SPGR) in the sagittal plane were applied. Results: Both the post-i.v. and post-i.a. Gd-DTPA images showed significantly higher signal-to-noise (SNR) and contrast-to-noise (CNR) in the joint cartilage compared to the non-enhanced images (P<0.002). I.a. Gd-DTPA provided significantly higher SNR and CNR compared to i.v. Gd-DTPA (P<0.01). Furthermore, a better delineation of the cartilage in the synovial/cartilage zone and of the chondral/subchondral border was observed. Conclusion: The dGEMRIC MRI method markedly improved delineation of hip joint cartilage compared to non-enhanced MRI. The i.a. Gd-DTPA provided the best cartilage delineation. dGEMRIC is a clinically applicable MRI method that may improve identification of early subtle cartilage damage and the accuracy of volume measurements of hip joint cartilage.

Wrist and Finger Joint MR Imaging in Rheumatoid Arthritis

Purpose: To elaborate the best MR imaging protocol for studies in rheumatoid arthritis (RA) and to evaluate the sensitivity and interobserver agreement with respect to detection of bone erosions (MR and radiography) and grading of synovial membrane hypertrophy (MR imaging only). Material and Methods: MR imaging and conventional radiography of wrist and metacarpophalangeal (MCP) joints were performed in 41 RA patients and 3 healthy controls. The following pulse sequences were applied: T1-weighted spin-echo (T1-SE) with and without contrast enhancement, T2-SE, T2-turbo-SE, T1-2D-FLASH, T1-3D-FLASH, fat-saturated-T1-SE, STIR and 3D-DESS. Results: Bone erosions were found by MR compared to radiography in 261 versus 85 bones of the wrist (ratio 3.1) and 59 versus 21 MCP joint quadrants (ratio 2.81). MR and radiography interobserver agreements were both approximately 90%. Likewise, MR scored synovial membrane hypertrophy in wrist and MCP joints with a high interobserver agreement. The most informative MR sequence appeared to be contrast-enhanced T1-SE MR, preferably with fat saturation. A STIR sequence or T2-weighted fat saturation sequence was useful in screening for joint disease. Conclusion: The sensitivity of MR is superior to conventional radiography with respect to detection of bone erosions in wrist and MCP joints. The interobserver agreement for MR and radiography was similar. Thus, MR of wrist and finger joints may become a useful supplement to conventional radiography in the evaluation of RA patients in clinical trials and clinical practice.

MR pulse sequences for selective relaxation time measurements: a phantom study.

The accuracy of relaxation time measurements of spectroscopic inversion recovery and CPMG multi-echo pulse sequences together with ISIS and stimulated echo-pulse methods have been tested on a reference phantom (test object no. 5, of the EEC Concerted Research Project). For the measurements a Siemens Magnetom wholebody magnetic resonance scanner operating at 1.5 Tesla was used. For comparison six imaging pulse sequences for relaxation time measurements were tested on the same phantom. The spectroscopic pulse sequences all had an accuracy better than 10% of the reference values.

Magnetic resonance imaging of the bone marrow in patients with acute leukemia during and after chemotherapy : changes in T1 relaxation

Twenty-seven patients with acute leukemia were examined at the time of diagnosis with MR imaging and in vivo T1 relaxation time measurements of the hemopoietic bone marrow. A 1.5 T whole body magnetic resonance scanner was used. Twenty of the patients had follow-up examinations in relation to chemotherapy. Bone marrow biopsies from the posterior iliac crest were obtained within a short time interval of all MR examinations. At the time of diagnosis, T1 relaxation times were increased significantly in all the leukemic patients, compared with 24 age-matched controls. A decrease in T1 relaxation time towards or into the normal range was observed in 10 patients who obtained remission. The T1 relaxation time remained prolonged in 6 patients who failed to obtain remission during chemotherapy. Four patients, who obtained remission with concomitant decrease of T1 values towards or into the normal range, also showed prolongation of T1 relaxation time in relation to leukemic relapse. The results indicate that changes observed in T1 relaxation times of the hemopoietic bone marrow in patients with acute leukemia reflect changes in disease activity, and, that serial measurements of T1 values may provide clinically useful information with the possibility for identification of residual disease in regions inaccessible for biopsy.

Cerebral magnetic resonance spectroscopy in Rett syndrome: Failure to detect mitochondrial disorder

A total of eight girls with Rett syndrome were examined, by 31phosphorous magnetic resonance spectroscopy (31P MRS) (4 girls), proton MRS (1H MRS) (4 girls), muscle biopsying (2 girls), and determination of pyruvate and lactate in plasma (5 girls), to investigate the hypothesis of a mitochondrial malfunction as the etiology for this neurologic disorder. Almost all examinations, including electron microscopy in search of structural mitochondrial abnormalities, gave normal results, the only exception being the not unexpected finding of slight neurogenic atrophy in the muscle biopsy specimen from a 15-year-old girl.

Magnetic resonance imaging of the bone marrow in patients with acute leukemia during and after chemotherapy

Twenty-seven patients with acute leukemia were examined at the time of diagnosis with MR imaging and in vivo T1 relaxation time measurements of the hemopoietic bone marrow. A 1.5 T whole body magnetic resonance scanner was used. Twenty of the patients had follow-up examinations in relation to chemotherapy. Bone marrow biopsies from the posterior iliac crest were obtained within a short time interval of all MR examinations. at the time of diagnosis, T1 relaxation times were increased significantly in all the leukemic patients, compared with 24 age-matched controls. A decrease in T1 relaxation time towards or into the normal range was observed in 10 patients who obtained remission. the T1 relaxation time remained prolonged in 6 patients who failed to obtain remission during chemotherapy. Four patients, who obtained remission with concomitant decrease of T1 values towards or into the normal range, also showed prolongation of T1 relaxation time in relation to leukemic relapse. the results indicate that change...