Magnetic Resonance Imaging Signal Intensity Research Articles

Evaluation of a tailored injection profile (TIP) algorithm for uniform contrast-enhanced signal intensity profiles in MR angiography.

To evaluate a contrast agent injection method that provides constant magnetic resonance imaging (MRI) signal intensity throughout a contrast-enhanced MR angiography acquisition. A tailored injection profile (TIP) algorithm was developed that used the signal intensity profile from a test bolus as an impulse response function, and predicted the response to various multiphasic injection profiles. Antecubital vein injections were administered via a commercially available multiphasic power injector. The TIP algorithm evaluated the predicted responses and selected the injection that best matched the desired (20-sec plateau) profile. Resulting signal intensity profiles from tailored and standard injection profiles were compared in 20 subjects (10 each). All subjects received a weight-based single-dose (0.1 mmol/kg) of gadoteridol, and abdominal aorta signal intensities were measured at 3T with a time-resolved, thick-slice, 3D spoiled-gradient-echo MR sequence with parameters approximating contrast-enhanced MR angiography. The single-phase, standard injection was injected at 1.6 mL/sec. Full-width at 80% maximum (FW80M) signal intensity was significantly longer for the tailored injection profiles (23.0 ± 2.2 vs. 9.0 ± 4.2 sec; P < 0.01). Concurrently, the profile peak signal intensity was reduced by 19% for the tailored profiles (12.0 ± 3.1 vs. 14.8 ± 2.8 times baseline; P = 0.058), nearly reaching significance. Multiphasic tailored injections from a power injector produced longer signal intensity profiles (156% increase in FW80M) with an accompanying decrease (19%) in peak signal intensity compared to a standard, single-phase injection. J. Magn. Reson. Imaging 2016. J. Magn. Reson. Imaging 2016;44:1664-1672.

Cell Therapy with Human Dermal Fibroblasts Enhances Intervertebral Disk Repair and Decreases Inflammation in the Rabbit Model.

Study Design Pilot study using the rabbit model. Objective Low back pain is often associated with disk degeneration. Cell therapy for degenerating disks may promote tissue regeneration and repair. Human dermal fibroblasts, obtained from the patient's skin tissue or donated tissue, may be a promising cell therapy option for degenerating disks. The objective of these studies is to determine the effects of intradiscal transplantation of neonatal human dermal fibroblasts (nHDFs) on intervertebral disk (IVD) degeneration by measuring disk height, magnetic resonance imaging (MRI) signal intensity, gene expression, and collagen immunostaining. Methods New Zealand white rabbits (n = 16) received an annular puncture to induce disk degeneration and were treated with nHDFs or saline 4 weeks later. At 2 and 8 weeks post-treatment, X-ray and MRI images were obtained. IVDs were isolated and examined for changes in collagen staining and gene expression. Results In the nHDF-treated group, there was a 10% increase in the disk height index after 8 weeks of treatment (p ≤ 0.05), and there was no significant difference in the saline-treated group. When compared with the saline-treated disks, disks treated with nHDFs showed reduced expression of inflammatory markers, a higher ratio of collagen type II over collagen type I gene expression, and more intense immunohistochemical staining for both collagen types I and II. Conclusions Human dermal fibroblast introduction into the disk reduced inflammation and promoted tissue rich in both type I and type II collagens. The results of this study suggest that nHDFs would be a feasible cell therapy option for disk degeneration.

Relationship between magnetic resonance imaging signal intensity and volume of extraocular muscles in thyroid-associated ophthalmopathy with methylprednisolone pulse therapy.

PurposeTo characterize the relationship between inflammation and swelling of extraocular muscles in thyroid-associated ophthalmopathy before and after methylprednisolone pulse therapy.MethodsThe signal intensities and volumes of the superior rectus (SR), inferior rectus (IR), lateral rectus (LR), medial rectus (MR), and superior oblique (SO) muscles were measured with magnetic resonance imaging in 25 eyes of 25 patients with thyroid-associated ophthalmopathy in the acute inflammatory phase before and after methylprednisolone pulse therapy. The signal intensity ratios (SIRs) of muscles and brain white matter were calculated.ResultThe mean SIRs before treatment were 2.28±0.74 in SR, 2.66±0.57 in IR, 2.03±0.42 in LR, 2.45±0.49 in MR, and 1.98±0.48 in SO muscles. The mean SIRs after treatment were 1.82±0.62, 1.84±0.52, 1.70±0.35, 1.95±0.46, and 1.60±0.36, respectively. The mean volumes (cm3) before treatment were 1.35±0.67 in SR, 1.21±0.39 in IR, 0.66±0.13 in LR, 0.94±0.31 in MR, and 0.58±0.14 in SO muscles. Those after treatment were 1.12±0.45, 0.91±0.31, 0.61±0.12, 0.85±0.28, and 0.49±0.11, respectively. The SIRs showed significantly positive correlations with volumes both before and after treatment in SR muscles (before, r=0.77; after, r=0.69), IR muscles (before, r=0.65; after, r=0.60), MR muscles (before, r=0.69; after, r=0.73), and SO muscles (before, r=0.52; after, r=0.50) (P<0.01 for all correlations).ConclusionSwelling reflected the inflammation in extraocular muscles of thyroid-associated ophthalmopathy both before and after treatment.

Graft bending angle is correlated with femoral intraosseous graft signal intensity in anterior cruciate ligament reconstruction using the outside-in technique

BackgroundThe purposes of this study were as follows: 1) to determine the correlation between the bending angle of the anterior cruciate ligament (ACL) graft at the femoral tunnel and the magnetic resonance imaging (MRI) signal intensity of the ACL graft and 2) to analyze the difference in the MRI signal intensity of the reconstructed ACL graft in different areas of the graft after single-bundle hamstring autograft ACL (SB ACL) reconstruction using an outside-in (OI) technique with bone-sparing retro-reaming. MethodsThirty-eight patients who underwent SB ACL reconstruction with the hamstring tendon autograft using the OI technique were enrolled in this study. All patients were assessed using three-dimensional computed tomography (CT) to evaluate femoral tunnel factors, including tunnel placement, tunnel length, tunnel diameter, and femoral tunnel bending angle. At a mean of 6.3±0.8months after surgery, 3.0-T MRI was used to evaluate the graft signal intensity using signal/noise quotient for high-signal-intensity lesions. ResultsAmong various femoral tunnel factors, only the femoral tunnel bending angle in the coronal plane was significantly (p=0.003) correlated with the signal/noise quotient of the femoral intraosseous graft. The femoral intraosseous graft had significantly (p=0.009) higher signal intensity than the other graft zone. Five cases (13.2%) showed high-signal-intensity zones around the femoral tunnel but not around the tibial tunnel. ConclusionAfter ACL reconstruction using the OI technique, the graft bending angle was found to be significantly correlated with the femoral intraosseous graft signal intensity, indicating that increased signal intensity by acute graft bending might be related to the maturation of the graft. Level of evidenceThis was a retrospective comparative study with Level III evidence.

Contribution of metals to brain MR signal intensity: review articles.

Various metals are essential nutrients in humans, and metal shortages lead to a variety of deficiency diseases. Metal concentration abnormalities may cause metal deposition in the brain, and magnetic resonance imaging (MRI) is the most potent and sensitive technique now available for detecting metal deposition given the difficulties associated with performing brain tissue biopsy. However, the brain contains many kinds of metals that affect the signal intensity of MRI, which has led to numerous misunderstandings in the history of metal analysis. We reviewed the history of brain metal analysis with histologic findings. Typically, manganese overload causes high signal intensity on T1-weighted images (T1WI) in the globus pallidus, iron overload causes low signal intensity in the globus pallidus on T2-weighted images, and gadolinium deposition causes high signal intensity in the dentate nucleus, globus pallidus, and pulvinar of thalamus on T1WI. However, because nonparamagnetic materials and other coexisting metals also affect the signal intensity of brain MRI, the quantitative analysis of metal concentrations is difficult. Thus, when analyzing metal deposition using MRI, caution should be exercised when interpreting the validity and reliability of the obtained data.

In vitro and in vivo magnetic resonance imaging with chlorotoxin-conjugated superparamagnetic nanoprobes for targeting hepatocarcinoma.

The present study aimed to assess the in vitro and in vivo magnetic resonance imaging (MRI) features of chlorotoxin (CTX)-conjugated superparamagnetic iron oxide (SPIO) nanoprobes. CTX-conjugated nanoprobes were composed of SPIO coated with polyethylene glycol (PEG) and conjugated with CTX. The nanoprobes were termed SPIO-PEG-CTX. MRI of the SPIO and SPIO-PEG-CTX solutions at a different concentration was performed with a 3.0-T MRI scanner (Philips Achieva 3.0T X Series; Phillips Healthcare, The Netherlands). Rabbit VX2 hepatocarcinoma was established by a traditional laparotomy method (injection of the tumor particles into the liver using a 15G syringe needle) following approval by the institutional animal care and use committee. Contrast-enhanced MRI of VX2 rabbits (n=8) was performed using the same MRI scanner with SPIO‑PEG-CTX solutions as the contrast agent. Data were analyzed with calibration curve and a paired t-test. The SPIO-PEG-CTX nanoparticles were successfully prepared. With increasing concentrations of the solutions, the MRI signal intensity was increased at T1WI, but decreased at T2WI, which were the same as that for SPIO. Rabbit VX2 carcinoma appeared as a low MRI signal at T1WI, and high at T2WI. After injection of the contrast agent, the MRI signal of carcinoma was decreased relative to that before injection at T2WI (1,161±331.5 vs. 1,346±300.5; P=0.004<0.05), while the signal of the adjacent normal hepatic tissues was unchanged (480.6±165.1 vs. 563.4±67.8; P=0.202>0.05). The SPIO-PEG-CTX nanoparticles showed MRI negative enhancement at T2WI and a targeting effect in liver cancer, which provides the theoretical basis for further study of the early diagnosis of hepatocellular carcinoma.

Abstract WP38: Lower Fluid Attenuated Inversion Recovery Magnetic Resonance Imaging Signal Intensity After Acute Ischemic Stroke is Associated With Better Discharge Outcomes in Thrombolysed Patients

Background: Increases in FLAIR MRI signal intensity (SI) after acute ischemic stroke (AIS) have been proposed as “tissue clocks”, reflecting the degree of ischemic injury and potential for recovery in brain tissue. We hypothesize that lower SI increases will be a biomarker for less severe tissue injury and hence is potentially salvageable. To test this, we investigated patients who were treated with tPA to determine whether better outcomes were associated with lower FLAIR SI. Methods: Using our Get with the Guidelines database, we retrospectively analyzed AIS patients admitted between 2011 to 2013 who received full-dose tPA based on institutional protocols. Patients were included if they received a CT scan at our hospital before tPA therapy, and MRI performed &lt; 1 h post CT included a usable FLAIR scan and evidence of stroke on acute DWI. SI ratio (SIR) was calculated on the FLAIR by selecting region of interests in hyperintense FLAIR areas that coincided with the acute DWI lesion and matching contralateral regions. Logistic regression analysis was performed using forward stepwise analysis to combine age, sex, admission NIHSS, SIR and onset-to-treatment (OTT) time to predict discharge outcome. Good outcome was defined as discharge to home or in-patient rehabilitation hospital. Results: There were 129 AIS patients who received tPA, and 57 met our imaging criteria. Patient characteristics were: mean±SD age 70±15 years, median [IQR] NIHSS 13 [7-18], OTT 2.1±1.1 h, time-to-MRI 2.1±1.0 h, 58% female and median SIR 1.13 [1.05-1.26]. On a univariate basis, only age (P&lt;0.0001) and NIHSS (P=0.005) were significant predictors of outcome. However, multivariate analysis showed that combining age (P=0.019), NIHSS (P=0.022), and SIR (P=0.018) was able to predict good discharge outcome with 100% [95% CI 63-100%] specificity and 90% [77-96%] sensitivity. Using age and NIHSS alone, resulted in the same specificity but only 71% [56-83%] sensitivity. Discussion: Controlling for age and admission NIHSS, we found that lower FLAIR SIR was a significant predictor of discharge outcome while OTT was not. This suggests that “tissue clocks” may be more accurate than “time clocks” for predicting tissue outcome, and ultimately functional outcome.

Small cell carcinoma of the rectum: A report of imaging results from four cases.

Small cell carcinoma of the rectum is extremely rare. The present study aimed to improve the recognition of computed tomography (CT) and magnetic resonance imaging (MRI) features observed in patients with small cell carcinoma of the rectum. A total of 4 cases of patients with histologically confirmed small cell carcinoma of the rectum were retrospectively reviewed. The imaging features assessed consisted of the thickening of the rectal wall, local tumor invasion, CT density, MRI signal intensity, lesion texture, contrast enhancement characteristics, lymphadenopathy and distant metastasis. All 4 patients displayed ring-like rectal wall thickening and hypodensity in comparison to the gluteus muscles on non-enhanced CT images. MRI demonstrated isointensity on T1-weighted images and hyperintensity on T2-weighted images. Thickening of the left wall of the rectum with patchy low attenuation and the presence of an exophytic mass was observed in 1 patient. Local tumor invasion was observed in the perirectal fat spaces of 4 patients, in the prostate gland and seminal vesicle of 1 patient, and in the left seminal vesicle of 1 patient. Heterogeneous attenuation was exhibited on non-enhanced CT images in 3 lesions, and 1 lesion exhibited heterogeneous intensity on non-enhanced MRI images. All the lesions observed demonstrated strong enhancement following contrast imaging. Lymphadenopathy was observed in 4 patients, liver metastasis in 3 patients, pulmonary metastasis in 2 patients and multiple bone metastases in 1 patient. Overall, small cell carcinoma of the rectum appeared to be more likely to metastasize to the liver, pulmonary, lymph nodes and bone. Distinguishing features of small cell carcinoma of the rectum were noted as a thickening rectal wall, the presence of soft-tissue tumors, local tumor invasion, lymphadenopathy and distant metastases. Pre-operative CT and MRI are required as an aid in selecting the correct treatment plan and for the prognosis assessment of patients.

MRI pallidal signal in children exposed to manganese in drinking water

BackgroundManganese (Mn) can have neurotoxic effects upon overexposure. We previously reported poorer cognitive and motor development in children exposed to Mn through drinking water, suggesting possible neurotoxic effects from Mn in water. Hyperintensity in the globus pallidus (GP) on T1-weighted magnetic resonance imaging (MRI) indicates excessive brain Mn accumulation. Previous studies have reported GP hyperintensity related to Mn exposure in occupationally exposed individuals. However, no study has used MRI in children exposed to Mn in drinking water and who show no sign of overt intoxication. ObjectiveTo examine MRI signal intensity in the GP in children exposed to contrasted levels of Mn in drinking water. MethodsWe enrolled 13 children exposed to low Mn concentration in water and 10 children (ages 9–15 years) with high concentration (median of 1 and 145μg/L, respectively). We calculated three MRI T1 indexes: (i) standard pallidal index (PI) using frontal white matter as reference; (ii) PI using pericranial muscles as reference; and (iii) T1 relaxation time. Each MRI index was compared between exposure groups, and with respect to the estimated Mn intake from water consumption. ResultsThe standard PI did not differ between Mn-exposure groups. However, children in the group with high water-Mn concentration had significantly lower pericranial muscles PI than those with lower exposure and, accordingly, higher T1 relaxation time. Mn intake from water consumption was not correlated with the standard PI, but was significantly related to the pericranial muscles PI and T1 relaxation time. Motor performance was significantly lower in the high-exposure group. ConclusionWe observed lower signal intensity in the GP of children with higher exposure to Mn from drinking water. This result stands in contrast to previous MRI reports showing GP hyperintensity with greater Mn exposure. Differences in exposure pathways are discussed as a potential explanation for this discrepancy.

Assessment of Pulp Regeneration Induced by Stem Cell Therapy by Magnetic Resonance Imaging

IntroductionThis study was designed to evaluate the usefulness of magnetic resonance imaging (MRI) to assess the regeneration of pulp tissue. MethodsMobilized dental pulp stem cells and granulocyte colony-stimulating factor with collagen were transplanted into mature pulpectomized teeth for pulp regeneration (n = 4). The controls consisted of pulpectomized teeth with or without collagen and normal teeth with intact pulp tissue (n = 4, each). The signal intensity (SI) of MRI using T2 sequences was compared after the extraction of teeth in dogs. MRI was correlated with the corresponding histologic findings. ResultsPulp tissue was fully regenerated 90 days after cell transplantation. On the other hand, the root canal was empty in the control collagen-transplanted teeth at 90 days. The SI of the normal teeth was significantly higher than that of nonvital pulpectomized teeth and the controls of collagen transplanted teeth at 90 days. The stem cell transplanted teeth showed a gradual decrease in the SI until 180 days at which time the SI was similar to that in the normal teeth and significantly higher than that in the teeth transplanted with collagen alone without the stem cells. ConclusionsThe changes in the SI of the pulplike tissue were consistent with the histologic findings, showing the potential usefulness of the noninvasive method to serially access the efficacy of pulp regenerative therapy.

Prediction of surgical outcome in compressive cervical myelopathy: A novel clinicoradiological prognostic score.

Context:Preoperative severity of myelopathy, age, and duration of symptoms have been shown to be highly predictive of the outcome in compressive cervical myelopathy (CCM). The role of radiological parameters is still controversial.Aims:Define the prognostic factors in CCM and formulate a prognostic score to predict the outcome following surgery in CCM.Settings and Design:Retrospective.Materials and Methods:This study included 78 consecutive patients with CCM treated surgically. The modified Japanese Orthopaedic Association (mJOA) scale was used to quantify severity of myelopathy at admission and at 12-month follow-up. The outcome was defined as good if the patient had mJOA score ≥16 and poor if the score was <16. Age, sex, duration of symptoms, comorbidities, intrinsic hand muscle wasting (IHMW), diagnosis, surgical technique, Torg ratio, instability on dynamic radiographs, and magnetic resonance imaging (MRI) signal intensity changes were assessed.Statistics:Statistical Package for the Social Sciences (SPSS) (version 20.0) was used for statistical analysis. The association was assessed amongst variables using logistic regression analysis. Parameters having a statistically significant correlation with the outcome were included in formulating a prognostic score.Results:Severity of myelopathy, IHMW, age, duration, diabetes, and instability on radiographs were predictive of the outcome with a P value <0.01. Genders, diagnosis, surgical procedure, Torg ratio, and intensity changes on MRI were not significantly related to the outcome. A 8-point scoring system was devised incorporating the significant clinicoradiological parameters, and it was found that nearly all patients (97.82%) with a score below 5 had good outcome and all patients (100%) with a score above 5 had poor outcome. The outcome is difficult to predict with a score of 5.Conclusions:Clinical parameters are better predictors of the outcome as compared to radiological findings, following surgery in CCM. A simple scoring system based on clinicoradiological parameters is suggested in this paper to predict the outcome following surgery in cases of CCM.

Assessment the Optimal Effect of Time of Repetition: Extrinsic Pulse Parameter on Gd-DTPA Enhanced, Spin-Echo T1-Weighted MR Images under Low Magnetic Field Strength

The contrast agent concentration, the time of repetition (TR) and magnetic field strength are significant parameters that influence for the accurate signal intensity (SI) in quantitative Magnetic Resonance Imaging (MRI). Therefore, this study was conducted to investigate and refine the dependence and the optimal effect of Time of Repetition (TR) on the relationship between signal intensity and Gd-DTPA (Gadolinium-diethylene-triaminepenta-acetic acid) concentration, after applying two-dimensional (2D) Spin Echo (SE) pulse sequence under low-field MRI. In addition to that, the optimal concentration of Gd-DTPA at given sequence parameters at low-field MRI was also evaluated. A water-filled phantom was constructed for a range of Gd-DTPA concentrations (0 - 6 mmol/L) and the mean signal intensities (SIs) were assessed in the defined region of interest on T1-weighted images with different TR values (40 - 2000 ms). The generated signal-concentration curves for Gd-DTPA revealed that increasing TR was associated with the increase of the overall SIs and the maximum relationship between SI to concentration. Moreover, the required Gd-DTPA concentration to produce the maximum SI was associated to decrease with the increase of TR. In addition to this, the application of beyond 100 ms TR values in this study with relatively higher concentrations (beyond 1 - 2 mmol/L) has resulted predominantly non-linear patterns in the signal-concentration curves and it appears the saturation or decay of the SIs due to T2 effect. From these results, it can be suggested that the selection of relatively lower Gd-DTPA concentration ( mmol/L) with less than 800 ms (<800 ms) TR values can produce a better linear relationship between the concertation and SIs in T1-weighted SE low field contrast-enhanced MRI. Furthermore, this study also outlined the significance and necessity of the optimization of TR in SE sequence in low field MRI prior to a particular examination.

Effect of depressurization pressure on methane recovery from hydrate–gas–water bearing sediments

Natural gas hydrates (NGHs) are a promising energy source with huge reserves. The dissociation characteristics of NGHs need to be clarified further for developing safe and efficient technology for its recovery. In this study, Classes 1 and 2 NGH deposits were simulated by forming methane hydrate (MH) in porous media, and MH dissociation induced by depressurization was investigated using magnetic resonance imaging (MRI). MRI showed the liquid water distribution, which was used to analyze MH formation and dissociation. The vessel pressure was also measured during the experiments, which was compared with the MRI mean intensity of liquid water. MH dissociation processes were measured and analyzed under different backpressures, from 2.2 to 2.8MPa. It was observed that liquid water hindered methane gas output during gas production; hydrate dissociation caused the movement of some liquid water, which usually led to fluctuations in MRI signal intensity. The experimental results also indicated that the MH dissociation pattern was affected by heat transfer; although a larger depressurization range led to faster dissociation, the average dissociation rate was controlled by heat transfer.

Estimation of minimum miscibility pressure (MMP) of CO2 and liquid n-alkane systems using an improved MRI technique

Minimum miscible pressure (MMP) of gas and oil system is a key parameter for the injection system design of CO2 miscible flooding. Some industrial standard approaches such as the experiment using a rising bubble apparatus (RBA), the slim tube tests (STT), the pressure–density diagram (PDD), etc. have been applied for decades to determine the MMP of gas and oil. Some theoretical or experiential calculations of the MMP were also applied to the gas–oil miscible system. In the present work, an improved technique based on our previous research for the estimation of the MMP by using magnetic resonance imaging (MRI) was proposed. This technique was then applied to the CO2 and n-alkane binary and ternary systems to observe the mixing procedure and to study the miscibility. MRI signal intensities, which represent the proton concentration of n-alkane in both the hydrocarbon rich phase and the CO2 rich phase, were plotted as a reference for determining the MMP. The accuracy of the MMP obtained by using this improved technique was enhanced comparing with the data obtained from our previous works. The results also show good agreement with other established techniques (such as the STT) in previous published works. It demonstrates increases of MMPs as the temperature rise from 20°C to 37.8°C. The MMPs of CO2 and n-alkane systems are also found to be proportional to the carbon number in the range of C10 to C14.

Neonatal brain MRI: how reliable is the radiologist's eye?

White matter (WM) analysis in neonatal brain magnetic resonance imaging (MRI) is challenging, as demonstrated by the issue of diffuse excessive high signal intensity (DEHSI). We evaluated the reliability of the radiologist's eye in this context. Three experienced observers graded the WM signal intensity on axial T2-weighted 1.5T images from 60 different premature newborns on 2 occasions 4 weeks apart with a semi-quantitative classification under identical viewing conditions. The intra- and inter-observer correlation coefficients were fair to moderate (Fleiss' kappa between 0.21 and 0.60). This is a serious limitation of which we need to be aware, as it can lead to contradictory conclusions in the challenging context of term-equivalent age brain MRI in premature infants. These results highlight the need for a semiautomatic tool to help in objectively analyzing MRI signal intensity in the neonatal brain.

Irreversible electroporation of hepatocellular carcinoma: preliminary report on the diagnostic accuracy of magnetic resonance, computer tomography, and contrast-enhanced ultrasound in evaluation of the ablated area.

Irreversible electroporation (IRE) is a new ablation modality. Our purpose was to describe the effectiveness and the safety of the treatment and to evaluate the magnetic resonance imaging (MRI), computed tomography (CT) and contrast-enhanced ultrasound (CEUS) diagnostic accuracy in HCC patients treated with IRE at 1-, 3-, and 6-month follow-up. In an 18-month period, we treated 24 HCC lesions in 20 patients unfit for surgery. MRI, CT and CEUS were performed before and one, 3 and 6 month after IRE. We employed the liver-specific contrast medium Primovist (gadolinium ethoxybenzyl dimeglumine) in MRI. After IRE the lesions were classified as responders or non-responders to the treatment according to the mRECIST and the complications were recorded. We evaluated the size, shape, signal intensity (T1-W, T2-W, and DWI) in MRI, dynamic contrast enhancement pattern for CEUS, CT and MRI and signal behavior during the liver-specific phase for MRI. According to mRECIST, at 1 month MRI and CEUS showed a complete response (CR) in 91.7% of cases (22/24) tumors, while there was partial response (PR) in the remaining 2/24 (8.3%) treated nodules; in CT study all ablated zone appeared as necrotic (CR 100%). The residual viable tumor in MRI and in CEUS study had similar diameter (10 mm). No new HCC were identified from MRI, CT or CEUS. At 3 months MRI and CEUS showed the same results seen after 1 month from the treatment. Twenty-two necrotic lesions, and 2 residual tumors were found (CR = 91.7% and PD = 8.3%). In MRI study the two cases of residual tumor tissue had a diameter of 11 and 12 mm each. At CEUS the diameter of residual HCC was similar to the diameter at 1 month. CT showed 23 necrotic areas and one residual viable tissue in the treated zone, with a diameter of 10 mm (CR = 95.3% and PD = 4.7%). No new foci of HCC were identified from all imaging studies. At 6 months MRI, CEUS, and CT showed 22 necrotic lesions and 2 residual tumors in ablated zone (CR = 91.7% and PD = 8.3%). At MRI the diameters of the two residual viable HCCs were 12 and 14 mm, at CEUS the diameters were 11 and 12 mm, while at CT the diameters were 10 and 10 mm. No statistical difference was evaluated between CR, PR, PD percentage values for MRI, CT and CEUS (p value > 0.05 at Chi-square test). No major vascular complication was recorded after IRE. Six out of 20 patients (30%) showed a transient hepatic intensity difference (THID) area within the normal liver parenchyma adjacent to the treated lesions. Two of the 20 patients (10%) showed an absent concentration of liver-specific contrast medium around the ablation zone. Two patients developed complications, consisting in a peripheral arteriovenous shunt and a segmental dilation of the intrahepatic biliary ducts. We found no statistically significant difference in morphology, size (variation in the largest diameter), signal intensity in T1-weighted images, in T2-weighted images, in DWI and in the related map of the apparent diffusion coefficient (ADC), presence or absence of contrast enhanced during the arterial, portal, and late phase in MRI, CT, and CEUS, and signal characteristic during the liver-specific phase in MRI of the ablation zone at 1, 3, and 6 months. IRE is a feasible, safe and efficient modality in the treatment of patients with non-resectable HCC. We had no major complication, even when the ablated lesion was adjacent to major branches of the portal vein. All images techniques showed similar accuracy during the follow-up at 1, 3, and 6 months in the assessment ablated zone.

A Feasibility Study to Determine Whether Clinical Contrast Enhanced Magnetic Resonance Imaging can Detect Increased Bladder Permeability in Patients with Interstitial Cystitis

Interstitial cystitis/bladder pain syndrome is a bladder pain disorder associated with voiding symptomatology and other systemic chronic pain disorders. Currently diagnosing interstitial cystitis/bladder pain syndrome is complicated as patients present with a wide range of symptoms, physical examination findings and clinical test responses. One hypothesis is that interstitial cystitis symptoms arise from increased bladder permeability to urine solutes. This study establishes the feasibility of using contrast enhanced magnetic resonance imaging to quantify bladder permeability in patients with interstitial cystitis. Permeability alterations in bladder urothelium were assessed by intravesical administration of the magnetic resonance imaging contrast agent Gd-DTPA (Gd-diethylenetriaminepentaacetic acid) in a small cohort of patients. Magnetic resonance imaging signal intensity in patient and control bladders was compared regionally and for entire bladders. Quantitative assessment of magnetic resonance imaging signal intensity indicated a significant increase in signal intensity in anterior bladder regions compared to posterior regions in patients with interstitial cystitis (p<0.01) and significant increases in signal intensity in anterior bladder regions (p <0.001). Kurtosis (shape of probability distribution) and skewness (measure of probability distribution asymmetry) were associated with contrast enhancement in total bladders in patients with interstitial cystitis vs controls (p <0.05). Regarding symptomatology interstitial cystitis cases differed significantly from controls on the SF-36®, PUF (Pelvic Pain and Urgency/Frequency) and ICPI (Interstitial Cystitis Problem Index) questionnaires with no overlap in the score range in each group. ICSI (Interstitial Cystitis Symptom Index) differed significantly but with a slight overlap in the range of scores. Data suggest that contrast enhanced magnetic resonance imaging provides an objective, quantifiable measurement of bladder permeability that could be used to stratify bladder pain patients and monitor therapy.

Quantitative T2 relaxation time and magnetic transfer ratio predict endplate biochemical content of intervertebral disc degeneration in a canine model.

BackgroundDirect measurement of disc biochemical content is impossible in vivo. Therefore, magnetic resonance imaging (MRI) is used to evaluate disc health. Unfortunately, current clinical imaging techniques do not adequately assess degeneration, especially in the early stage of cartilage endplate, and subchondral bone zone (CEPZ). Therefore, this study aimed to investigate the sensitivity of quantitative MRI methods, namely T2 relaxation time and Magnetic Transfer Ratio (MTR), to identify early disc degeneration, especially for the CEPZ, using an experimental canine model of intervertebral disc injury and to investigate their sensitivity in depicting biochemically and histologically controlled degenerative changes in the disc.MethodsSixteen juvenile dogs underwent iatrogenic annular disruption via stab incisions. The animals underwent repeated 3.0 T MR imaging, and were sacrificed 4, 8, and 12 weeks post-operatively. A continuous rectangle drawing method was used to select regions of interest for the intervertebral disc from the cephalic to caudal CEPZ including the vertebrae, nucleus pulposus (NP) and annulus fibrosus (AF), which resembled pixel measurement for imaging analysis. Presence of degenerative changes was controlled by biochemical and histological analyses. The correlations between histological score, biochemical content, and quantitative MRI signal intensities were also analyzed.ResultsBoth T2 relaxation time and MTR values changed for CEPZ, NP, and AF tissues within 12 weeks. T2 relaxation time values decreased significantly in the NP, AF, and CEPZ separately at pre-operation, 4, 8, and 12 weeks when compared each time (P < 0.05). MTR values showed no significant differences for the CEPZ between 8 and 4 weeks or 12 weeks, or compared to pre-operative values; there were significant differences for the AF. Biochemical and histological analysis showed changes consistent with quantitative MRI signal intensities for early stage degeneration.ConclusionsEarly traumatic or degenerative changes are detectable with both T2 and MTR. T2 changes were more sensitive to the differences in disc status, especially for the CEPZ. Since T2 and MTR reflect different disc properties, performing both imaging under the same conditions would be helpful in the evaluation of disc degeneration. The continuous rectangle drawing can be a sensitive method to detect the changes of CEPZ.Electronic supplementary materialThe online version of this article (doi:10.1186/s12891-015-0610-6) contains supplementary material, which is available to authorized users.

SU-E-I-81: Targeting of HER2-Expressing Tumors with Dual PET-MR Imaging Probes

Purpose: The detection of human epidermal growth factor receptor type 2 (HER2) expression in malignant tumors provides important information influencing patient management. Radionuclide in vivo imaging of HER2 may permit the detection of HER2 in both primary tumors and metastases by a single noninvasive procedure. Trastuzumab, effective in about 15 % of women with breast cancer, downregulates signalling through the Akt/PI3K and MAPK pathways.These pathways modulate metabolism which can be monitored by positron emission tomography (PET) and magnetic resonance imaging (MRI). Methods: The relationship between response of HER2 overexpressing tumours and changes in imaging PET or SPECT and MRI will be examined by a integrated bimodal imaging probe.Small (7 kDa) high-affinity anti-HER2 Affibody molecules and KCCYSL targeting peptide may be suitable tracers for visualization of HER2-expressing tumors. Peptide-conjugated iron oxide nanoparticles (Fe3O4 NPs) as MRI imaging and CB-TE2A as PET imaging are integrated into a single synthetic molecule in the HER2 positive cancer. Results: One of targeted contrast bimodal imaging probe agents was synthesized and evaluated to target HER2-expressing tumors in a HER2 positive rat model. We will report the newest results regarding the development of bimodal imaging probes. Conclusion: The preliminary results of the bimodal imaging probe presents high correlation of MRI signal and PET imaging intensity in vivo. This unique feature can hardly be obtained by single model contrast agents. It is envisioned that this bimodal agents can hold great potential for accurate detection of HER2-expressing tumors which are critical for clinical management of the disease.

Ex vivo magnetic resonance imaging in South African manganese mine workers

BackgroundManganese (Mn) exposure is associated with increased T1-weighted magnetic resonance imaging (MRI) signal in the basal ganglia. T1 signal intensity has been correlated with occupational Mn exposure but not with clinical symptomatology or neuropathology. ObjectivesThis study investigated predictors of ex vivo T1 MRI basal ganglia signal intensity in neuropathologic tissue obtained from deceased South African mine workers. MethodsA 3.0T MRI was performed on ex vivo brain tissue obtained from 19 Mn mine workers and 10 race- and sex-matched mine workers of other commodities. Basal ganglia regions of interest were identified for each subject with T1-weighted intensity indices generated for each region. In a pathology subset, regional T1 indices were compared to neuronal and glial cell density and tissue metal concentrations. ResultsIntensity indices were higher in Mn mine workers than non-Mn mine workers for the globus pallidus, caudate, anterior putamen, and posterior putamen with the highest values in subjects with the longest cumulative Mn exposure. Intensity indices were inversely correlated with the neuronal cell density in the caudate (p=0.040) and putamen (p=0.050). Tissue Mn concentrations were similar in Mn and non-Mn mine workers. Tissue iron (Fe) concentration trended lower across all regions in Mn mine workers. ConclusionsMn mine workers demonstrated elevated basal ganglia T1 indices when compared to non-Mn mine workers. Predictors of ex vivo T1 MRI signal intensity in Mn mine workers include duration of Mn exposure and neuronal density.