Measuring hepatic functional reserve using T1 mapping of Gd-EOB-DTPA enhanced 3T MR imaging: A preliminary study comparing with 99mTc GSA scintigraphy and signal intensity based parameters

PurposeTo determine the utility of liver T1-mapping on gadolinium-ethoxybenzyl-diethylenetriamine-pentaacetic acid (Gd-EOB-DTPA) enhanced magnetic resonance (MR) imaging for the measurement of liver functional reserve compared with the signal intensity (SI) based parameters, technetium-99m-galactosyl serum albumin (^99mTc-GSA) scintigraphy and indocyanine green (ICG) clearance.Materials and methodsThis retrospective study included 111 patients (Child-Pugh-A 90; −B 21) performed with both Gd-EOB-DTPA enhanced liver MR imaging and ^99mTc-GSA (76 patients with ICG). Receiver operating characteristic (ROC) curve analysis was performed to compare diagnostic performances of T1-relaxation-time parameters [pre-(T1pre) and post-contrast (T1hb) Gd-EOB-DTPA], SI based parameters [relative enhancement (RE), liver-to-muscle-ratio (LMR), liver-to-spleen-ratio (LSR)] and ^99mTc-GSA scintigraphy blood clearance index (HH15)] for Child-Pugh classification. Pearson’s correlation was used for comparisons among T1-relaxation-time parameters, SI-based parameters, HH15 and ICG.ResultsA significant difference was obtained for Child-Pugh classification with T1hb, ΔT1, all SI based parameters and HH15. T1hb had the highest AUC followed by RE, LMR, LSR, ΔT1, HH15 and T1pre. The correlation coefficients with HH15 were T1pre 0.22, T1hb 0.53, ΔT1 −0.38 of T1 relaxation parameters; RE −0.44, LMR −0.45, LSR −0.43 of SI-based parameters. T1hb was highest for correlation with HH15. The correlation coefficients with ICG were T1pre 0.29, T1hb 0.64, ΔT1 −0.42 of T1 relaxation parameters; RE −0.50, LMR −0.61, LSR −0.58 of SI-based parameters; 0.64 of HH15. Both T1hb and HH15 were highest for correlation with ICG.ConclusionT1 relaxation time at post-contrast of Gd-EOB-DTPA (T1hb) was strongly correlated with ICG clearance and moderately correlated HH15 with ^99mTc-GSA. T1hb has the potential to provide robust parameter of liver functional reserve.     

Relationship between <Superscript>99m</Superscript>Tc-GSA scintigraphic indices of liver function reserve and portal circulation in patients with chronic liver disease

Objectives In order to predict the prognosis or complications of portal hypertension in patients with chronic liver disease, it is important to evaluate both hepatic functional reserve and portal circulation. On ^99mTc-galactosyl human serum albumin (^99mTc-GSA) scintigraphy, the index of blood clearance (HH15) and receptor index (LHL15) have been widely used to evaluate the hepatic functional reserve. However, the relationship between these indices and portal circulation is unknown. The purpose of this study was to examine the relationship between HH15 and LHL15 and portosystemic shunts evaluated with arteriographic portography or esophagogastroduodenoscopy. Methods A total of 82 patients with chronic liver disease (mean age, 66.7 years) who underwent ^99mTc-GSA scintigraphy, arteriographic portography, and esophagogastroduodenoscopy were enrolled. HH15 and LHL15 were obtained from dynamic ^99mTc-GSA scintigraphy. The patients were divided into three groups according to the arteriographic portography findings: group 1, no portal collateral circulation; group 2, mild collateral development; and group 3, moderate to severe collateral development. They were also divided into three groups based on the esophagogastroduodenoscopic findings: group A, no varices; group B, small-caliber varices; and group C, enlarged varices. The Kruskal–Wallis test was used to compare each index among these groups. Receiver operating characteristic (ROC) analysis was used to determine whether each index was an indicator for the presence of portosystemic shunts. Results Both HH15 and LHL15 differed significantly between groups 1 and 2 and between groups 1 and 3. However, only HH15 differed significantly between groups A and B and between groups A and C. On the basis of the ROC analysis, the HH15 threshold value of 0.62 yielded both excellent sensitivity (83.9%) and specificity (84.6%) for the presence of portosystemic shunts, as evaluated with arteriographic portography. The HH15 threshold value of 0.64 yielded both good sensitivity (66.1%) and specificity (69.2%) for the presence of portosystemic shunts, as evaluated with esophagogastroduodenoscopy, whereas no adequate threshold value of LHL15 was found for the presence of portosystemic shunts. Conclusions HH15 is a potent indicator of the presence of portosystemic shunts in chronic liver disease.     

Improved reproducibility of simple quantitative indices from 99mTc-GSA liver functional imaging

Objective

We evaluated intra- and interoperator reproducibilities in calculating the conventional indices HH15 and LHL15 from ^99mTc-diethylenetriamine pentaacetic acid galactosyl human serum albumin (^99mTc-GSA) scintigraphy, and proposed new, simple methods for the calculation of quantitative indices.

Methods

The results of ^99mTc-GSA scintigraphy in 33 patients were retrospectively analyzed. Heart and liver ROIs were drawn manually to cover cardiac blood pool and entire liver, respectively, and HH15 and LHL15 were calculated. In addition, square regions of interest (ROIs) of fixed sizes were placed at the highest activity in blood pool and the liver. Using the square heart ROI, sHH15, an equivalent of HH15, was computed. Fractional liver uptake at 15 min (FLU15) was calculated using the square heart and liver ROIs. Intra- and interoperator reproducibilities, as well as correlation with Indocyanine green retention rate at 15 min (ICG R15), were assessed for these four indices by linear regression analysis.

Results

Substantial intra- and interoperator variabilities were found for HH15 and LHL15. The correlation coefficients for intra- and interoperator comparisons were 0.884 and 0.869 for HH15, respectively, and 0.919 and 0.917 for LHL15, respectively. The use of square ROIs instead of hand-drawn ROIs improved reproducibility. The correlation coefficients for intra- and interoperator comparisons were 0.988 and 0.973 for sHH15, respectively, and 0.989 and 0.975 for FLU15, respectively. Correlation with ICG R15 was better for sHH15 (r = 0.619) and FLU15 (r = ?0.656) than for HH15 (r = 0.439) and LHL15 (r = ?0.490).

Conclusions

HH15 and LHL15 showed substantial intra- and interoperator variabilities, and the use of square ROIs are indicated to provide better reproducibility.     

Assessment of colorectal hepatic metastases by quantitative T2 relaxation time

Aim

To determine the T₂ relaxation time of colorectal hepatic metastases and changes in T₂ relaxation times following chemotherapy.

Materials and methods

42 patients with 96 hepatic colorectal metastases underwent baseline MRI. Axial T₁, T₂ and multi-echo GRASE sequences were acquired. ROIs were drawn on T₂ relaxation maps, obtained from GRASE images, encompassing metastasis and normal liver to record T₂ relaxation time values. In 11 patients with 28 metastases, MRI was repeated using same protocol at 6 weeks following chemotherapy. The median pre-treatment T₂ values of metastases and normal liver were compared using the Mann–Whitney test. The pre- and post-treatment median T₂ values of metastases were compared using the Wilcoxon–Rank test for responding (n = 16) and non-responding (n = 12) lesions defined by RECIST criteria. The change in T₂ values (ΔT₂) were compared and correlated with percentage change in lesion size.

Results

There was no difference in the pre-treatment median T₂ of metastases between responding (67.3 ± 8.6) and non-responding metastases (71.4 ± 16.5). At the end of chemotherapy, there was a decrease in the median T₂ of responding lesions (61.6 ± 12.6) p = 0.83, and increase in non-responding lesions (76.2 ± 18.4) p = 0.03, but these were not significantly different from the pre-treatment values. There was no significant difference in ΔT₂ of responding and non-responding lesions (p = 0.18) and no correlation was seen between size change and ΔT₂ (coefficient = 0.3).

Conclusion

T₂ relaxation time does not appear to predict response of colorectal liver metastasis to chemotherapy.     

Lymphomas and glioblastomas: differences in the apparent diffusion coefficient evaluated with high b-value diffusion-weighted magnetic resonance imaging at 3T

Background and purpose

As the usefulness of the apparent diffusion coefficient (ADC) obtained from diffusion-weighted images (DWI) for the differential diagnosis between glioblastoma and primary central nervous system lymphoma is controversial, we assessed whether high b-value DWI at b 4000 s/mm² could discriminate between glioblastoma and lymphoma. We also compared the power of high- and standard b-value (b-4000, b-1000) imaging on a 3-Tesla (3 T) magnetic resonance (MR) instrument.

Materials and methods

This study was approved by our Institutional Review Board. We acquired DWI at 3 T with b = 1000 and b = 4000 s/mm² in 10 patients with lymphoma and 14 patients with glioblastoma. The ADC was measured by placing multiple regions of interest (ROI) on ADC maps of the site of enhanced lesions on contrast-enhanced T1-weighted MR images. We avoided hemorrhagic and cystic lesions by using T1-, T2-, FLAIR-, and T2* MR images. The ADC values of each tumor were determined preoperatively from several ROI and expressed as the minimum-, mean-, and maximum ADC value (ADC_MIN, ADC_MEAN, ADC_MAX). We evaluated the relationship between ADCs and histological information including tumor cellularity.

Results

All ADC values were statistically associated with tumor cellularity. ADC_MIN at b-4000 was associated with tumor cellularity more significantly than ADC_MIN at b-1000. All ADC values were lower for lymphoma than glioblastoma and the statistical difference was larger at b = 4000- than b = 1000 s/mm². According to the results of discriminant analysis, the log likelihood was greatest for ADC_MIN at b = 4000. At a cut-off value of ADC_MIN = 0.500 × 10⁻³ mm²/s at b-4000 it was possible to differentiate between lymphoma and glioblastoma (sensitivity 90.9%, specificity 91.7%).

Conclusions

Calculating the ADC value is useful for distinguishing lymphoma from glioblastoma. The lowest degree of overlapping and a better inverse correspondence with tumor cellularity were obtained with ADC_MIN at b-4000 s/mm² at 3 T MRI.     

Age-related differences in metabolites in the posterior cingulate cortex and hippocampus of normal ageing brain: a 1H-MRS study

Objective

To study age-related metabolic changes in N-acetylaspartate (NAA), total creatine (tCr), choline (Cho) and myo-inositol (Ins).

Materials and methods

Proton magnetic resonance spectroscopy (¹H-MRS) was performed in the posterior cingulate cortex (PCC) and the left hippocampus (HC) of 90 healthy subjects (42 women and 48 men aged 18–76 years, mean ± SD, 48.4 ± 16.8 years). Both metabolite ratios and absolute metabolite concentrations were evaluated. Analysis of covariance (ANCOVA) and linear regression were used for statistical analysis.

Results

Metabolite ratios Ins/tCr and Ins/H₂O were found significantly increased with age in the PCC (P < 0.05 and P ≤ 0.001, respectively), and in the HC (P < 0.01 for both). An increased tCr/H₂O was only observed in the PCC (P < 0.01). Following absolute quantification based on the internal water signal, significantly increased concentrations of Ins and tCr in the PCC confirmed the relative findings (P < 0.01 for both).

Conclusion

Age-related increases of tCr and Ins are found in the PCC, whereas this holds only true for Ins in the HC, indicating possible gliosis in the ageing brain. No age-dependent NAA decreases were observed in the PCC nor the HC. The ¹H-MRS results in these specific brain regions can be important to differentiate normal ageing from age-related pathologies such as mild cognitive impairment (MCI) and Alzheimer's disease.     

High b-value diffusion-weighted MR imaging of normal brain at 3T

Introduction

The purpose of this study was to determine the normative apparent diffusion coefficient (ADC) values at 3 T using high b-value (3000 s/mm²) diffusion-weighted images (DWI) and compare the signal characteristics of the high b value with standard b-value (1000 s/mm²) DWI.

Methods

Institutional review board approval was obtained for this prospective study which included 20 volunteers (10 M, 10 F, mean age: 38.7 ± 14.9) without any known clinical disease or radiological findings. All brain examinations were performed with 3 T MR by using similar parameters of b1000 and b3000 DWI sequences. DWI and ADC maps were obtained. Signal intensity, noise, signal to noise ratio (SNR), contrast to noise (CNR), contrast ratio (CR), and ADC values of bilateral posterior limb of internal capsule, frontal white matter, parietal gray matter, pons, thalamus, splenium of corpus callosum were measured on b1000 and b3000 DW images.

Results

In all anatomic locations, MR signal intensity, SNR and ADC values of b3000 images were significantly lower than MR signal intensity, SNR and ADC values of b1000 images (p < 0.001). The CNR and CR values at the posterior limb of internal capsule and pons were significantly increased on b3000 images (p < 0.001) and decreased in the other regions measured.

Conclusion

The ADC values calculated from standard b-value DWI were significantly higher than those calculated from high b-value DWI. These results agree with the previous studies. In the regions where CNR values increase with high b value, b3000 DWI images may provide additional clinical information.     

T1ρ and T2 mapping of the proximal tibiofibular joint in relation to aging and cartilage degeneration

Objective

To study the effects of aging and cartilage degeneration of the proximal tibiofibular- and femorotibial joint (PTFJ, FTJ) on the cartilage of the PTFJ using T₁ρ and T₂ mapping.

Materials and methods

We performed sagittal T₁ρ and T₂ mapping of the PTFJ and FTJ on 55 subjects with knee disorders. We placed 3 regions of interest (ROIs) on images of the cartilage in the PTFJ, medial femoral condyle (MFC), and medial tibia plateau (MTP). Correlation analysis was performed for the T₁ρ and T₂ values of each ROI and the patient age and the osteoarthritic grade of the PTFJ and FTJ.

Results

The T₁ρ and T₂ values of the PTFJ were affected neither by aging nor the osteoarthritic grade of the FTJ. Values of the FTJ normalized to PTFJ values were correlated with the osteoarthritic grade of the FTJ in the MFC (r = 0.851 and 0.779, respectively) and the MTP (r = 0.635 and 0.762, respectively). There was a significant difference in the T₁ρ but not the T₂ value of the PTFJ and MFC between normal and mildly osteoarthritic cartilage of each joint.

Conclusion

We document that the T₁ρ and T₂ values of PTFJ cartilage were not affected by aging or cartilage degeneration in the FTJ. The T₁ρ value of the PTFJ may represent a useful internal standard reference for evaluating early degeneration of the FTJ.     

Association of platelet-SDF-1 with hemodynamic function and infarct size using cardiac MR in patients with AMI

Purpose

Platelet-derived stromal-cell-derived factor-1 (SDF-1) plays an important role in trafficking hematopoetic progenitor cells for tissue regeneration and neovascularisation.The aim was to evaluate platelet-SDF-1 and CD34⁺ progenitor cells in patients with acute myocardial infarction (AMI) compared with hemodynamic function and infarct size using late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) imaging.

Materials and methods

We consecutively evaluated 40 patients with AMI, who received coronary angiography for primary coronary intervention. Blood was sampled for flow cytometry to determine mean fluorescence intensity (MFI) of platelet-SDF-1 and for isolation of CD34⁺ progenitor cells. 48 h and three months after coronary stenting, all patients underwent 1.5 T CMR for volumetric assessment and LGE.

Results

Patients with enhanced platelet-SDF-1 expression (median ≥ 68.5 MFI) showed a significant amelioration of left ventricular ejection fraction (LVEF) (baseline vs. follow-up mean ± SD: 45 ± 6% vs. 56 ± 6%; P = 0.018) and of stroke volume (73.1 ± 19.1 mL vs. 89.9 ± 21.3 mL; P = 0.032) at three-month follow-up in contrast to patients with a decreased platelet-SDF-1 expression level (LVEF: 53 ± 8% vs. 56 ± 10%; P = 0.267; stroke volume: 85.6 ± 23.1 mL vs. 87.4 ± 23.2 mL; P = 0.803). Inversely, LGE infarct size showed significantly reduced in patients with enhanced platelet-SDF-1 expression at three months (18.9 ± 12 mL vs. 6.3 ± 5.1 mL; P = 0.002) compared to patients with decreased platelet-SDF-1 (12.7 ± 12.7 mL vs. 7.6 ± 8.4 mL; P = 0.156). Time-dependent autocorrelation coefficients shifted for both SV (lag 1: r = −0.368; P = 0.001) and the number of CD34⁺ cells (lag 1: r = 0.633; P = 0.001) to a positive autocorrelation (SV; lag 2: r = 0.295; P = 0.001; CD34⁺ cells; lag 2: r = 0.287; P = 0.001). Patients with increased number of CD34⁺ cells (median ≥ 420 cells/hpf) showed a significant amelioration of stroke volume in three-month follow-up (83.9 ± 5.3 mL vs. 99.4 ± 4.1 mL; P = 0.020) compared with patients with decreased number of CD34⁺ cells (69.3 ± 4.1 mL vs. 76.1 ± 3.2 mL; P = 0.282).

Conclusions

Platelet-SDF-1 and number of CD34⁺ progenitor cells are associated with CMR hemodynamic function in patients with AMI.     

An easy and reproducible semi-automatic method for the evaluation of99mTc-galactosyl human serum albumin

^99mTc-galactosyl human serum albumin (^99mTc-GSA) scintigraphy is a new method for evaluating liver function. This scintigraphy is useful for evaluating the severity of liver diseases. The indices evaluating hepatic function include the receptor index (LHL15) and the index of blood clearance (HH15). These indices are calculated on the basis of the regions of interest (ROIs) for both whole liver and heart, and are susceptible to the ROIs over heart and liver. At present, there is no standard method for determining ROIs. We attempted to establish a standard method which shall not be subject to inter and/or intra operator variation. A computer program to determine heart and liver ROIs semi-automatically was developed. Ten patients (12 instances) were studied with^99mTc-GSA, and HH15 and LHL15 were calculated on the basis of the ROIs obtained manually and semiautomatically by 3 different operators independently. Blood sampling and gamma-counting yielded blood clearance data. The ICG R15 was compared with each index in 34 patients. The time needed for ROI determination was reduced from 2–3 minutes for the manual method to 0.5–0.8 minutes for the semi-automatic method. The % coefficients of variation (% CVs) of HH15 and LHL15 were improved in the order manual-inter observer (M-inter), manual-intra observer (M-intra) and semiautomated-inter observer (SA-inter); % CVs of HH15 were 2.26% for M-inter, 1.55% for M-intra and 0.07% for SA-inter, and % CVs of LHL15 were 2.29% for M-inter, 0.46% for M-intra and 0.07% for SA-inter. The correlation of HH15 and LHL15 among M-inter, M-intra and SA-inter was good. Comparison of indices obtained by manual and semi-automatic methods with blood clearance data obtained by blood sampling and gamma-counting showed good correlations and no significant differences. The comparison with ICG R15 showed that HH15 and LHL15 by the semi-automated method gave better correlation that that by the manual method. A newly developed semi-automated method improved data processing time and deviation of indices in^99mTc-GSA studies. This method should substitute for manual ROI determination.     

Reproductibility of apparent diffusion coefficients measurements in diffusion-weighted MRI of the abdomen with different b values

Purpose

To test the reproducibility of apparent diffusion coefficients (ADC) measurements of the normal liver, kidney and spleen parenchyma with different b values.

Materials and methods

Eleven healthy volunteers were imaged twice with use of the same protocol. Each DWI was performed with b-factors of 0, 100 and 500 s/mm². The ADCs were organized according to session (1 or 2), anatomic location and repetition (twice with two different b value per session). The ADC data were analyzed with repeated-measures analysis of variance to demonstrate the influence of anatomic location, session and different b values. The coefficient of variation was calculated for each subject, b value and anatomic location, then analyzed by using repeated-measures analysis of variance.

Results

There were significant differences in mean ADCs among the three anatomic locations and with different b values (P < .05). There were no significant differences in ADCs between imaging sessions 1 or 2 for both b values (P > .05). The CV values range between 7.3% and 14.7%. There were no significant differences in CV values neither between the two b values nor for the various organ locations (P > .05).

Conclusion

Using the same technical parameters, patients and the same observer, CV values range between 7.3% and 14.7%. And we recommend to be careful in examination and comparison of the measured ADC values, below these limits, without knowledge technical parameters that has been used, otherwise differences that are merely because of changes in the measurement technique could be interpreted as differences because of progression of disease or therapy.     

Diffusion-weighted MR imaging for detection of extrahepatic cholangiocarcinoma

Objectives

To measure the sensitivity of diffusion-weighted imaging (DWI) and determine the most appropriate b value for DWI; to explore the correlation between the apparent diffusion coefficient (ADC) value and the degree of extrahepatic cholangiocarcinoma differentiation.

Methods

Preoperative diffusion-weighted imaging and magnetic resonance examinations were performed for 31 patients with extrahepatic cholangiocarcinoma. Tumor ADC values were measured, and the signal-to-noise ratio, contrast-to-noise ratio, and signal-intensity ratio between the diffusion-weighted images with various b values as well as the T2-weighted images were calculated. Pathologically confirmed patients were pathologically graded to compare the ADC value with different b values of tumor at different degrees of differentiation, and the results were statistically analyzed by using the Friedman test.

Results

A total of 29 cases of extrahepatic cholangiocarcinoma were detected by DWI. As the b value increased, tumor signal-to-noise ratio and contrast-to-noise ratio between the tumor and normal liver gradually decreased, but the tumor signal-intensity ratio gradually increased. When b = 800 s/mm², contrast-to-noise ratio between tumor and normal liver, tumor signal-intensity ratio, and tumor signal-to-noise ratio of diffusion-weighted images were all higher than those of T2-weighted images; the differences were statistically significant (P < 0.05). As the b value increased, the tumor ADC value gradually declined. As the degree of differentiation decreased, the tumor ADC value declined.

Conclusion

The b value of 800 s/mm² was the best in DWI of extrahepatic cholangiocarcinoma; the lesion ADC value declined as the degree of cancerous tissue differentiation decreased.     

Estimation of liver function using T2* mapping on gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid enhanced magnetic resonance imaging

Purpose

To investigate the usefulness of T2* mapping of liver on gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI for estimating liver function.

Materials and methods

33 patients were classified into 3 groups as follows: normal liver function (NLF) (n = 7); mild liver damage (MLD) (n = 16) with Child-Pugh A; severe liver damage (SLD) (n = 10) with Child-Pugh B. T2*-weighted gradient-echo (T2*W-GRE) and T1-weighted gradient-echo (T1W-GRE) images were obtained before and after Gd-EOB-DTPA administration (3, 8, 13, and 18 min; 5, 10,15, and 20 min; respectively). T2* mapping of liver was calculated from T2*W-GRE, then T2* values of liver and T2* reduction rates of T2* value between pre- and post-contrast enhancement were measured. The increase rates of liver-to-muscle signal intensity (LMS) ratio on T1W-GRE between pre- and post-contrast enhancement were calculated.

Results

T2* values on pre- and post-contrast showed no significant differences among three groups. Significant differences in T2* reduction rates were found among groups, and those of LCB were lower than those of other groups (NLF:MLD:SLD, 3.8:6.0:0.6% at 3 min, 8.2:10.3:1.0% at 8 min, 10.7:11.5:1.2% at 13 min, and 16.1:13.2:3.5% at 18 min, respectively) (P < 0.05). Significant differences in increase rates of LMS ratio on T1W-GRE were identified (NLF:MLD:SLD, 1.53:1.46:1.35 at 5 min, 1.68:1.64:1.37 at 10 min, 1.79:1.76:1.44 at 15 min, and 1.89:1.78:1.49 at 20 min, respectively).

Conclusion

T2* reduction rate and increase rate of LMS ratio on T1W-GRE may allow us estimation of liver function according to Child-Pugh score.     

Pancreatic iron stores assessed by magnetic resonance imaging (MRI) in beta thalassemic patients

Purpose

To assess the correlation between MRI findings of the pancreas with those of the heart and liver in patients with beta thalassemia; to compare the pancreas T2* MRI results with glucose and ferritin levels and labile plasma iron (LPI).

Materials and methods

We retrospectively evaluated chronically transfused patients, testing glucose with enzymatic tests, serum ferritin with chemiluminescence, LPI with cellular fluorescence, and T2* MRI to assess iron content in the heart, liver, and pancreas. MRI results were compared with one another and with serum glucose, ferritin, and LPI. Liver iron concentration (LIC) was determined in 11 patients’ liver biopsies by atomic absorption spectrometry.

Results

289 MRI studies were available from 115 patients during the period studied. 9.4% of patients had overt diabetes and an additional 16% of patients had impaired fasting glucose. Both pancreatic and cardiac R2* had predictive power (p < 0.0001) for identifying diabetes. Cardiac and pancreatic R2* were modestly correlated with one another (r² = 0.20, p < 0.0001). Both were weakly correlated with LIC (r² = 0.09, p < 0.0001 for both) and serum ferritin (r² = 0.14, p < 0.0001 and r² = 0.03, p < 0.02, respectively). None of the three served as a screening tool for single observations. There is a strong log–log, or power-law, relationship between ratio of signal intensity (SIR) values and pancreas R2* with an r² of 0.91.

Conclusions

Pancreatic iron overload can be assessed by MRI, but siderosis in other organs did not correlate significantly with pancreatic hemosiderosis.     

Clinical usefulness of dual-time FDG PET-CT in assessment of esophageal squamous cell carcinoma

Purpose

We conducted this study to investigate the value of the dual-time 2-[¹⁸F]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography–computed tomography (PET–CT) in assessment of the primary tumor, loco-regional lymph node and distant metastasis in patients with esophageal squamous cell carcinoma.

Methods

Twenty-six patients with histologically proved esophageal squamous cell carcinoma underwent dual-time FDG PET–CT before radical surgery. The standardized uptake values (SUV_max) were obtained including early SUV_max and delayed SUV_max, respectively. The retention index (RI) was also calculated. The results were evaluated retrospectively according to the final pathologic findings. Four diagnostic criteria including (1) early SUV_max ≧ 2.5 alone, (2) RI ≧ 10% alone, (3) a combination of early SUV_max ≧ 2.5 and RI ≧ 10%, and (4) a combination of early SUV_max ≧ 2.5 or RI ≧ 10% were used for differentiating malignancy from a benign lesion, respectively.

Results

The sensitivity of FDG PET–CT in detecting the primary tumor with combination of early SUV_max ≧ 2.5 or RI ≧ 10% was 96.2%. It was statistically significantly higher than the results using the other three criteria (p < 0.0001). For loco-regional lymph node detection, there was no significant difference among the 4 criteria. For distal metastases, the significantly higher specificity (100%) was found when using combination of early SUV_max ≧ 2.5 and RI ≧ 10% or using early SUV_max ≧ 2.5 alone than using the other two criteria (p = 0.0058). With regard to accuracy, no significant correlations were observed among primary tumor, loco-regional lymph nodes and distant metastasis (p > 0.05).

Conclusion

The preliminary result of this study demonstrated that dual-time point FDG PET–CT had limited value in detection of primary tumor and loco-regional lymph nodes metastasis. For the distant metastasis, the sensitivity and specificity would be improved if RI ≧ 10% is used as a supplemental criterion. Efforts should be made to improve the ability of the dual-time FDG PET–CT technique to assess primary tumor and loco-regional lymph nodes metastasis.     

Self-expandable stent loaded with 125I seeds: feasibility and safety in a rabbit model

Objective

To evaluate technical feasibility and acute and subacute radiotolerance of a self-expandable stent loaded with ¹²⁵I seeds in the rabbit esophagus.

Methods

A self-expandable stent designed for esophageal application was made of 0.16 mm nitinol wire and loaded with ¹²⁵I seeds (CIAE-6711). Twenty-seven stents with three different radioactive dosages (n = 9 in each dosage group) were implanted in the esophagus of healthy rabbits, while nine stents alone were used as controls. The stents were perorally deployed into the esophagus under fluoroscopic guidance. Radiological follow-up included plain chest film, CT scan, and barium esophagography which were undertaken in all rabbits of each group at 2, 4, and 8 weeks, respectively, which were correlated to histopathological findings. The stented esophageal segments along with their adjacent tissues were harvested for histopathological examinations.

Results

The stent was successfully deployed into the targeted esophageal segment in all rabbits. Neither ¹²⁵I seeds dislodged from the stent during the deployment, nor they did during the follow-up period. The greatest (16.2 Gy) absorbed dose was found in the tissue 10 mm from ¹²⁵I seeds at 8 weeks.Slight epithelial hyperplasia on the stent surface and submucosal inflammatory process developed at 2 weeks, which reached the peak at 8 weeks after the procedure. Significant thickness of the esophageal muscular layer was found at 8 weeks only in the groups with ¹²⁵I seeds. On radiologic follow-up, moderate strictures on both ends of the stents developed at 4 weeks and became severe at 8 weeks after the procedure in all groups.

Conclusion

Deployment of a self-expandable stent loaded with ¹²⁵I seeds is technically feasible and safe within the first 8 weeks. Acute and subacute radiotolerance of the treated esophagus and its adjacent tissues by ¹²⁵I seeds is well preserved in a healthy rabbit model.     

Patterns of pulmonary tuberculosis on FDG-PET/CT

Objective

This study aims to describe patterns of pulmonary tuberculosis (TB) on FDG-PET/CT.

Methods

All patients with a diagnosis of TB and who underwent FDG-PET/CT between January 2009 and June 2010 were included. Clinical, biological and imaging data were reviewed. TB was proven either on bacteriological or histopathological studies (n = 13) or on a clinical and imaging basis (n = 3).

Results

Sixteen patients (11 men; median age 56, range 22–84 years) were included. Two distinct patterns were identified. In the lung pattern (9/16), patients had predominantly pulmonary symptoms (6/9 patients, 67%) with a parenchymal involvement: uptakes on lung consolidation ± cavitation surrounded by micronodules. Mediastino-hilar lymph nodes were slightly enlarged (15 mm, 10–27) with moderate uptake (3.9, 2.5–13.4). In the lymphatic pattern (7/16), patients had predominantly systemic symptoms (5/7 cases, 71%) and all had extra-thoracic involvement. Mediastino-hilar lymph nodes were more enlarged (30 mm, 18–35, p = 0.03) and with higher uptake (6.8, 5.7–16.8, p = 0.034) than in the lung pattern.

Conclusion

We identified two distinct patterns of pulmonary TB on FDG-PET/CT. The lung pattern related to a restricted and slight hypermetabolic infection and the lymphatic pattern related to a systemic and intense infection. Combined interpretation of PET and CT findings improves the specificity of images, especially for the lung pattern.     

Validity of apparent diffusion coefficient hyperpolarized 3He-MRI using MSCT and pulmonary function tests as references

Purpose

To compare apparent diffusion coefficient (ADC) measurements from hyperpolarized (HP) helium (³He)-magnetic resonance imaging (MRI) with quantitative data from multislice Computed Tomography (CT) (MSCT) of the whole lungs and pulmonary function tests (PFT).

Materials and methods

Twenty-seven subjects, 22 with established emphysema and 5 with preclinical emphysema defined by PFT criteria, were examined with HP ³He-MRI and MSCT. Mean age was 55 (±12) years, 18 female and 9 male. Mean ADC from ³He-MRI was compared with emphysema index (EI), 15th percentile and mean lung density (MLD) values from MSCT. Both mean ADC and MSCT data were compared to PFT, especially percent of predicted diffusing capacity of carbon monoxide (%predicted DLCO), using Pearson's correlation test.

Results

Mean ADC and standard deviation values were 0.392 ± 0.119 cm²/s for the established emphysema group and 0.216 ± 0.046 for the pre-clinical emphysema group. MSCT values for the established emphysema group and pre-clinical emphysema group were: EI (%) 11 ± 12 and 0.4 ± 0.6, respectively; 15th percentile (Hounsfield Units (HU)), −956 ± 25 and −933 ± 13, respectively and MLD (HU) −877 ± 20 and −863 ± 15, respectively. Correlations between mean ADC and EI and 15th percentile were both r = 0.90 and for MLD r = 0.59. There was higher correlation between mean ADC and %predicted DLCO (r = 0.90) than between EI and %predicted DLCO (r = 0.76).

Conclusion

HP ³He-MRI correlates well with density measurements from MSCT and agrees better than MSCT with %predicted DLCO which is the PFT most related to emphysema.     

Iron deposition of the deep grey matter in patients with multiple sclerosis and neuromyelitis optica: a control quantitative study by 3D-enhanced susceptibility-weighted angiography (ESWAN)

Purpose

Previous studies have detected abnormal iron deposition in the deep grey matter (DGM) of multiple sclerosis (MS). The regional specificity of the DGM iron deposition in neuromyelitis optica (NMO) is still unclear. We compared the differences in the DGM iron concentration between MS and NMO patients.

Methods

We enrolled 42 relapsing–remitting MS (RRMS) patients, 42 NMO patients and 42 healthy controls undergoing brain conventional MRI and three-dimensional (3D)-enhanced T₂*-weighted angiography (ESWAN) sequences. We obtained the mean phase values (MPVs) for ESWAN-filtered phase images. An analysis of covariance (ANCOVA) was used to compare MPVs among three groups. The correlations of MPVs changes with disease duration and expanded disability status scale (EDSS) were analyzed.

Results

The RRMS patients had higher DGM iron concentration than did the NMO and control groups, but only the bilateral substantia nigra (SN) showed a significant statistical difference among three groups (p < 0.05). In the RRMS group, the iron concentration in the bilateral head of the caudate nucleus (HCN) (left: p < 0.0001; right: p = 0.0134) and the dentate nucleus (DN) (p < 0.05 for both) were correlated with disease duration. In the NMO group, no correlation was found between the DGM iron concentration and disease duration (p > 0.05). Furthermore, no correlations were found between the DGM iron concentration and EDSS (p > 0.05).

Conclusions

We confirm the iron concentration in the DGM iron content of MS patients is more than NMO patients and healthy controls in the same age range. Furthermore, the disease duration was found to be a significant contributor to patients with MS.