Comparison of cardiac volumetry using real-time MRI during free-breathing with standard cine MRI during breath-hold in children.

BACKGROUND: Cardiac real-time magnetic resonance imaging (RT-MRI) provides high-quality images even during free-breathing. Difficulties in post-processing impede its use in clinical routine. OBJECTIVE: To demonstrate the feasibility of quantitative analysis of cardiac free-breathing RT-MRI and to compare image quality and volumetry during free-breathing RT-MRI in pediatric patients to standard breath-hold cine MRI. MATERIALS AND METHODS: Pediatric patients (n = 22) received cardiac RT-MRI volumetry during free breathing (1.5 T; short axis; 30 frames per s) in addition to standard breath-hold cine imaging in end-expiration. Real-time images were binned retrospectively based on electrocardiography and respiratory bellows. Image quality and volumetry were compared using the European Cardiovascular Magnetic Resonance registry score, structure visibility rating, linear regression and Bland-Altman analyses. RESULTS: Additional time for binning of real-time images was 2 min. For both techniques, image quality was rated good to excellent. RT-MRI was significantly more robust against artifacts (P < 0.01). Linear regression revealed good correlations for the ventricular volumes. Bland-Altman plots showed a good limit of agreement (LoA) for end-diastolic volume (left ventricle [LV]: LoA -0.1 ± 2.7 ml/m2, right ventricle [RV]: LoA -1.9 ± 3.4 ml/m2), end-systolic volume (LV: LoA 0.4 ± 1.9 ml/m2, RV: LoA 0.6 ± 2.0 ml/m2), stroke volume (LV: LoA -0.5 ± 2.3 ml/m2, RV: LoA -2.6 ± 3.3 ml/m2) and ejection fraction (LV: LoA -0.5 ± 1.6%, RV: LoA -2.1 ± 2.8%). CONCLUSION: Compared to standard cine MRI with breath hold, RT-MRI during free breathing with retrospective respiratory binning offers good image quality, reduced image artifacts enabling fast quantitative evaluations of ventricular volumes in clinical practice under physiological conditions.

Advantages of a combined rheumatoid arthritis magnetic resonance imaging score (RAMRIS) for hand and feet: does the RAMRIS of the hand alone underestimate disease activity and progression?

BACKGROUND: To evaluate a combined rheumatoid arthritis magnetic resonance imaging score (RAMRIS) for hand and foot (HaF-score) in rheumatoid arthritis (RA). METHODS: Magnetic resonance imaging (MRI, 0.2 Tesla) of the dominant hand and foot of 26 ACPA positive RA patients before and 6 months after initiation of methotrexate was obtained. RAMRIS of the hand was complemented by corresponding scoring of the foot (MTP I-V; HaF-score). Disease Activity Score 28 (DAS28) and a tender and swollen joint count (JC) of the joints scored in MRI were recorded. Changes in these scores (Δ) were assessed. RESULTS: ΔHaF-score correlated significantly with ΔDAS28 (r = 0.820, 95%-CI 0.633-0.916). Correlations to ΔDAS28 were best for changes in the synovitis subscore (0.648) and bone marrow edema (0.703). Correlations to ΔDAS28 were significantly better for of the ΔHaF-score than ΔRAMRIS (0.499, 0.139-0.743, p = 0.0368).All patients with at least moderate response (EULAR criteria, n = 11) had continuing disease activity on MRI, including five cases with new erosions, three of them at the feet. Improvements of the hand JC or foot JC were seen in 16 and 15 cases, respectively. However, MRI of the hand or feet improved in only 10 and 9 cases, respectively. No patient fulfilled SDAI remission criteria. CONCLUSIONS: The HaF-score identifies patients with continuing disease activity despite clinical response that would have been missed by consideration of the traditional RAMRIS or the DAS28 alone. Response as opposed to remission may be an insufficient goal in RA as all patients showed continuing disease activity, especially at the feet.

Hybrid [¹8F]-FDG PET/MRI including non-Gaussian diffusion-weighted imaging (DWI): preliminary results in non-small cell lung cancer (NSCLC).

PURPOSE: To assess the feasibility of non-Gaussian DWI as part of a FDG-PET/MRI protocol in patients with histologically proven non-small cell lung cancer. MATERIAL AND METHODS: 15 consecutive patients with histologically proven NSCLC (mean age 61 ± 11 years) were included in this study and underwent whole-body FDG-PET/MRI following whole-body FDG-PET/CT. As part of the whole-body FDG-PET/MRI protocol, an EPI-sequence with 5 b-values (0, 100, 500, 1000 and 2000 s/mm(2)) was acquired for DWI of the thorax during free-breathing. Volume of interest (VOI) measurements were performed to determine the maximum and mean standardized uptake value (SUV(max); SUV(mean)). A region of interest (ROI) was manually drawn around the tumor on b=0 images and then transferred to the corresponding parameter maps to assess ADC(mono), D(app) and K(app). To assess the goodness of the mathematical fit R(2) was calculated for monoexponential and non-Gaussian analysis. Spearman's correlation coefficients were calculated to compare SUV values and diffusion coefficients. A Student's t-test was performed to compare the monoexponential and non-Gaussian diffusion fitting (R(2)). RESULTS: T staging was equal between FDG-PET/CT and FDG-PET/MRI in 12 of 15 patients. For NSCLC, mean ADC(mono) was 2.11 ± 1.24 × 10(-3) mm(2)/s, Dapp was 2.46 ± 1.29 × 10(-3) mm(2)/s and mean Kapp was 0.70 ± 0.21. The non-Gaussian diffusion analysis (R(2)=0.98) provided a significantly better mathematical fitting to the DWI signal decay than the monoexponetial analysis (R(2)=0.96) (p<0.001). SUV(max) and SUV(mean) of NSCLC was 13.5 ± 7.6 and 7.9 ± 4.3 for FDG-PET/MRI. ADC(mono) as well as Dapp exhibited a significant inverse correlation with the SUV(max) (ADC(mono): R=-0.67; p<0.01; Dapp: R=-0.69; p<0.01) as well as with SUV(mean) assessed by FDG-PET/MRI (ADC(mono): R=-0.66; p<0.01; Dapp: R=-0.69; p<0.01). Furthermore, Kapp exhibited a significant correlation with SUV(max) (R=0.72; p<0.05) and SUV(mean) as assessed by FDG-PET/MRI (R=0.71; p<0.005). CONCLUSION: Simultaneous PET and non-Gaussian diffusion acquisitions are feasible. Non-Gaussian diffusion parameters show a good correlation with SUV and might provide additional information beyond monoexponential ADC, especially as non-Gaussian diffusion exhibits better mathematical fitting to the decay of the diffusion signal than monoexponential DWI.

Patterns of magnetic resonance imaging of the foot in rheumatoid arthritis: which joints are most frequently involved?

To investigate patterns of inflammatory MRI pathologies of the fore- and midfoot in rheumatoid arthritis (RA) and early RA (ERA) and their changes under therapy. In this prospective study, MRI data of the foot of 39 RA patients (29 female, 10 male; age: 54 ± 13 years; disease duration: 35 ± 37 months; baseline DAS28: 3.0 ± 2.0; medication: 29 DMARD, 1 biological, 9 symptomatic or non-specific treatment) were evaluated for synovitis in 314 joints, bone marrow edema and erosions according to RAMRIS criteria in a total of 585 joints. The change in joint pathology intensity was evaluated on follow-up MRI (time of follow-up: 8 ± 4 months) in 25 patients. Inflammation was generally more frequent in the metatarsophalangeal (MTP) joints (221/292; 76 %) than in the proximal metatarsal (47/292; 16 %) and tarsal bones (24/292; 8 %). The overall most frequently involved joints of the foot were MTP 5 (51/292; 18 %) and 1 (49/292; 17 %). Change under therapy was most frequently seen in the MTP 1 joint. Progress of inflammation in the MTP 1 was more frequently found in ERA patients than in patients with established RA (disease duration >12 months) (p = 0.002). In RA, the MTP joints, primarily MTP 5 and 1, are the predominant sites of inflammatory MRI pathologies of the foot. A change of inflammatory activity under therapy can be most frequently noted in the MTP 1 joint. This information might be helpful to improve effectiveness of MRI-controlled therapy approaches and clinical trials.

Utility of combined high-resolution bone SPECT and MRI for the identification of rheumatoid arthritis patients with high-risk for erosive progression.

OBJECTIVES: To evaluate the utility of sequentially acquired, post hoc fused, magnetic resonance imaging (MRI) and multi-pinhole single photon emission computed tomography (MPH-SPECT) with technetium-99m-labeled disphosphonates (Tc99m-DPD) for the identification of finger joints with later erosive progression in early rheumatoid arthritis (ERA) patients. METHODS: Ten consecutive ERA patients prospectively underwent MPH-SPECT and MRI of metacarpophalangeal (MCP) joints prior to and after 6 months methotrexate therapy. Tc99m-DPD uptake was measured at proximal and distal MCP sites using regional analysis. The course of joint pathologies was scored according to the Rheumatoid Arthritis MRI Score (RAMRIS) criteria. RESULTS: The frequency of increased Tc99m-DPD uptake, synovitis and bone marrow edemadecreased under MTX therapy; but the number of bone erosions increased. Joints with progressive and new erosions on follow-up had a higher baseline Tc99m-DPD uptake (2.64 ± 1.23 vs. 1.43 ± 0.91) (p=0.02). CONCLUSIONS: Joints with erosive progression are characterized by an early increased Tc99m-DPD uptake, even in absence of MRI bone pathologies. Tc99m-DPD MPH-SPECT might thus be of additional value to morphological MRI for the identification of RA patients with a high risk for erosive progression.

Does positron emission tomography data acquisition impact simultaneous diffusion-weighted imaging in a whole-body PET/MRI system?

OBJECTIVES: The purpose of this study was to test whether the acquisition of positron emission tomography (PET) does interfere with simultaneous diffusion weighted imaging (DWI) in an integrated whole-body PET/MRI system. MATERIAL AND METHODS: Fourteen consecutive oncological patients (9 men, 5 women; age 54 ± 13 years ([mean ± standard deviation]) scheduled for routine [(18)F]-FDG PET/CT were prospectively enrolled. For DWI, an echo planar imaging (EPI) sequence (b=0-500-1000 s/mm(2)) was acquired twice on an integrated whole-body 3T PET/MRI system in each patient; first with simultaneous PET acquisition and a second time with the PET component switched off. The apparent diffusion coefficient (ADC) and the signal-to-noise ratio at b=1000 s/mm(2) (SNR) of the myocardium, paraspinal muscle, liver, spleen, renal cortex and tumor tissue (if present) were measured. In addition, the coefficient of variation (CV) of ADC values was calculated. Student's t-test for paired samples was performed to test for differences of the mean ADC, ADC CV and SNR between DWI with and without simultaneous PET acquisition. RESULTS: There were no significant differences of the ADC [(mean ± standard deviation)] between the DWI acquisitions with and without simultaneous PET acquisition for the myocardium (2572 ± 441 × 10(-6)mm(2)/s and 2586 ± 376 × 10(-6)mm(2)/s, respectively) (P=0.817), paraspinal muscle (1279 ± 254 × 10(-6)mm(2)/s vs. 1219 ± 181 × 10(-6)mm(2)/s) (P=0.318), liver (1245 ± 158 × 10(-6)mm(2)/s vs. 1254 ± 171 × 10(-6)mm(2)/s) (P=0.848), spleen (980 ± 122 × 10(-6)mm(2)/s vs. 1000 ± 187 × 10(-6)mm(2)/s) (P=0.676) and renal cortex (1951 ± 226 × 10(-6)mm(2)/s vs. 1930 ± 273 × 10(-6)mm(2)/s) (P=0.730). Mean ADC of lymph node metastases (n=6) did not differ between with PET acquisition (853 ± 174 × 10(-6)mm(2)/s) and without simultaneous PET (865 ± 170 × 10(-6)mm(2)/s) (P=0.675). There were no significant differences between the CV of ADC values or the SNR values measured in DWI datasets that were acquired with or without simultaneous PET for any evaluated organ site. CONCLUSION: The simultaneous acquisition of DWI and PET on an integrated PET/MRI system does not impact ADC quantification of normal and tumor tissue and does not alter SNR. This knowledge provides a basis for the use of simultaneous multiparametric PET/MRI comprising DWI in diagnostic imaging and quantitative tumor therapy monitoring using repeated ADC measurements.

Synovitis and bone inflammation in early rheumatoid arthritis: high-resolution multi-pinhole SPECT versus MRI.

PURPOSE: We aimed to assess the relationship between bone inflammation in multi-pinhole single-photon emission computed tomography (MPH-SPECT) and synovitis detected by magnetic resonance imaging (MRI) in early rheumatoid arthritis patients. MATERIALS AND METHODS: MPH-SPECT with technetium dicarboxypropanedisphosphonate (Tc-99mDPD) and 3 Tesla MRI were performed in 10 early rheumatoid arthritis patients. Eighty finger joint sites were assessed for increased osteoblastic activity using visual and region-of-interest (ROI) analysis. Presence of joint inflammation in MRI was investigated using the subscores of the rheumatoid arthritis MRI score. RESULTS: Tc-99mDPD uptake was increased in 38 (47.5%) and 22 (27.5%) joint sites as determined by visual and ROI analysis, respectively. A total of 32 (84.2%) sites with increased bone metabolism showed a normal MRI bone signal. The MPH-SPECT uptake ratio was elevated only in the subgroup with severe synovitis (P < 0.001). CONCLUSION: In early rheumatoid arthritis, molecular imaging with MPH-SPECT detects higher rates of inflammatory bone involvement compared to MRI. Our preliminary data suggest that osteitis is related to severe synovitis.

The val158met polymorphism of human catechol-O-methyltransferase (COMT) affects anterior cingulate cortex activation in response to painful laser stimulation.

BACKGROUND: Pain is a complex experience with sensory, emotional and cognitive aspects. Genetic and environmental factors contribute to pain-related phenotypes such as chronic pain states. Genetic variations in the gene coding for catechol-O-methyltransferase (COMT) have been suggested to affect clinical and experimental pain-related phenotypes including regional mu-opioid system responses to painful stimulation as measured by ligand-PET (positron emission tomography). The functional val158met single nucleotide polymorphism has been most widely studied. However, apart from its impact on pain-induced opioid release the effect of this genetic variation on cerebral pain processing has not been studied with activation measures such as functional magnetic resonance imaging (fMRI), PET or electroencephalography. In the present fMRI study we therefore sought to investigate the impact of the COMT val158met polymorphism on the blood oxygen level-dependent (BOLD) response to painful laser stimulation. RESULTS: 57 subjects were studied. We found that subjects homozygous for the met158 allele exhibit a higher BOLD response in the anterior cingulate cortex (ACC), foremost in the mid-cingulate cortex, than carriers of the val158 allele. CONCLUSION: This result is in line with previous studies that reported higher pain sensitivity in homozygous met carriers. It adds to the current literature in suggesting that this behavioral phenotype may be mediated by, or is at least associated with, increased ACC activity. More generally, apart from one report that focused on pain-induced opioid release, this is the first functional neuroimaging study showing an effect of the COMT val158met polymorphism on cerebral pain processing.

Human immunodeficiency virus 1-associated minor motor disorders: perfusion-weighted MR imaging and H MR spectroscopy.

PURPOSE: To investigate whether advanced magnetic resonance (MR) imaging techniques such as diffusion-weighted (DW) and perfusion-weighted (PW) MR imaging and hydrogen 1 (1H) MR spectroscopy can depict functional and pathophysiologic mechanisms in patients who have minor motor deficits (MMDs) associated with human immunodeficiency virus 1 (HIV-1). MATERIALS AND METHODS: Thirty-two patients with results seropositive for HIV-1 and different degrees of HIV-1-related MMD underwent conventional brain MR imaging, as well as DW and PW MR imaging and 1H MR spectroscopy of the basal ganglia. PW MR imaging data were computed pixel by pixel for creation of time-to-peak, relative regional cerebral blood volume, and bolus amplitude parameter maps. In addition, quantitative regional cerebral blood flow (rCBF) maps were calculated with respect to the arterial input function by using the singular value decomposition algorithm. For 1H MR spectroscopy, a stimulated echo acquisition mode 20, or STEAM 20, sequence was used. Spectra were fit for determination of the signal intensities of the different metabolites. According to psychomotor testing results, patients were divided into three groups: group 1, 10 patients with normal motor function; group 2, eight patients with psychomotor slowing for the first time; and group 3, 14 patients who had had sustained pathologic psychomotor slowing for at least 6 months before the MR imaging examination. RESULTS: No patients had an abnormality at either conventional or DW MR imaging. PW MR imaging depicted significantly elevated rCBF in group 2 patients (P =.039, analysis of variance [ANOVA]) and significantly elevated myo-inositol-to-creatine ratio levels in group 3 patients (P =.020, ANOVA). CONCLUSION: Quantitative PW MR imaging and 1H MR spectroscopy can depict pathologic changes in patients who have HIV-1-related MMD but normal clinical examination and conventional MR imaging findings.