Hepatic magnetic resonance imaging with T2* mapping of ovariectomized rats: correlation between iron overload and postmenopausal osteoporosis

Objective

To explore the correlation between liver iron overload and bone mineral density (BMD) in an ovariectomy (OVX) rat model, using liver magnetic resonance (MR)-T2* and dual-energy X-ray absorptiometry (DEXA).

Methods

Sprague–Dawley rats received deferoxamine (DFO) or phosphate-buffered saline 3 months after bilateral OVX. MRI and DEXA were performed pre- and postoperatively. Five rats per group were killed every month for micro-CT, histopathology and biochemical examinations. Statistical analysis was performed with independent-samples t tests, box plots and Pearson’s correlation analysis.

Results

At 2 months postoperatively, BMD was significantly lower in the OVX group than in the control group (P?<?0.01), corresponding to the increased serum ferritin concentration (SFC; P?<?0.01) and liver iron concentration (LIC; P?<?0.01). Liver T2* values significantly differed between the two groups at 1 month postoperatively (P?<?0.001) and improved 1 month after DFO injection (P?<?0.05). These values were significantly and positively correlated with BMD in the control (r?=?0.527, P?<?0.001) and OVX (r?=?0.456, P?<?0.001) groups.

Conclusion

Liver MRI T2* changed markedly earlier than BMD, LIC and SFC, and correlated well with osteoporosis; it may thus be a valuable early indicator of osteoporosis.

Key Points

? Iron overload plays a vital role in the pathogenesis of postmenopausal osteoporosis. ? Liver T2* relaxation time is a sensitive value in reflecting iron overload. ? Liver T2* mapping elucidates changes in postmenopausal osteoporosis earlier than BMD. ? Iron chelation increases BMD in ovariectomized rats. ? Liver T2* has a moderate positive correlation with BMD.     

Hepatocellular carcinoma with marginal superparamagnetic iron oxide uptake on T2*-weighted magnetic resonance imaging: histopathologic correlation

Purpose

To evaluate the characteristics of hepatocellular carcinomas (HCCs) with marginal superparamagnetic iron oxide (SPIO) uptake on T2*-weighted MRI.

Materials and methods

The study group consisted of 73 patients with 83 surgically resected HCCs. Preoperative SPIO-enhanced MRI studies were retrospectively reviewed. Marginal SPIO uptake was considered positive if a rim-like or band-like low intensity area was present on SPIO-enhanced T2*-weighted images. The prevalence of marginal SPIO uptake was evaluated. Pathological specimens with hematoxylin and eosin staining and immunohistochemical staining of CD68 were reviewed in HCCs with marginal SPIO uptake and 33 HCCs without marginal SPIO uptake (control group).

Results

Ten of 83 (12%) HCCs showed marginal SPIO uptake. All HCCs were hypervascular, and only one nodule showed a nodule-in-nodule appearance on imaging findings. The pathology specimens suggested possible causes of marginal SPIO uptake, including marginal macrophage infiltration in moderately or poorly differentiated HCC (n = 4), residual normal hepatic tissue at the marginal area of confluent multinodular or single nodular with extranodular growth type HCC (n = 3), and a well-differentiated HCC component in nodule-in-nodule type HCC (n = 3). Marginal macrophage infiltration was not seen in the control group.

Conclusion

SPIO-enhanced MRI may be able to demonstrate marginal macrophage infiltration in HCC.     

Reproducibility and biological basis of in vivo T2* magnetic resonance imaging of liver metastasis of colorectal cancer

In this study, the reproducibility of MR imaging in colorectal liver metastases was assessed and values were correlated with the expression of the hypoxia‐related markers GLUT‐1 and CA‐IX as well as the relative vascular area, and the vessel density in resected tumors. The reproducibility of was analyzed in 18 patients with in total 22 colorectal liver metastases using the Bland and Altman method for the 16th, 50th, and 84th percentile values. Immunohistochemical staining was performed on 17 resected tumors obtained from 16 patients. The median of all liver metastases was 25.0 ± 5.6 ms vs. 23.0 ± 4.1 ms (median ± st.dev.) in normal liver. The coefficient of repeatability was 11.2 ms and the limits of agreement were ?13.2 ms and 9.1 ms for median values. On average, showed fair reproducibility. No correlations between values, hypoxia‐ and vascularity‐related markers were observed. Magn Reson Med, 70:1145–1152, 2013. © 2012 Wiley Periodicals, Inc.     

Neovascularisation in Achilles tendons with painful tendinosis but not in normal tendons: an ultrasonographic investigation

Chronic Achilles tendinosis is a condition with unknown aetiology and pathogenesis, most often, but not always, associated with painful nodular thickening of the tendon. In this investigation, 28 tendons (21 patients) with a painful nodule located at the 2-6 cm level in the tendon, and 20 normal (pain-free) tendons, were examined with grey-scale ultrasonography combined with colour Doppler examination. In all tendons with a painful nodule, but not in any of the normal pain-free tendons, neovascularisation was seen in the area with tendon changes (localised widening of the tendon with focal hypo-echoic areas). In tendons with advanced changes, vessels were seen through the entire widened part of the tendons, and both arterial and venous blood flows were registered. The neovascularisation found in this investigation might have implications on the pathogenesis of chronic Achilles tendinosis.     

Effect of ovariectomy on magnetic resonance T2* in rat femur

Measurements have been made in the rat femur in vivo and ex vivo by using an asymmetric spin echo technique of T_2′, the susceptibility contribution to T₂*. The trabecular spacing in this study in rat bone is considerably less than in previous studies in the human. A significant increase in T_2′ was seen in vivo 3 mm proximal to the growth plate with ovariectomy (a model of osteopenia), from 8.1 ± 0.7 to 10.0 ± 0.6 ms. Parallel changes in trabecular bone mineral density measured by quantitative computed tomography were found. T_2′ was higher in living bones than in the same bones measured post mortem.     

Achilles tendons: clinical relevance of neovascularization diagnosed with power Doppler US

PURPOSE: To evaluate the clinical relevance of neovascularization diagnosed with power Doppler ultrasonography (US) in Achilles tendons in patients with chronic achillodynia. MATERIALS AND METHODS: Forty consecutive patients (mean age, 52 years; age range, 30-72 years) were examined. US was performed bilaterally and repeated after 3 months. Shape and echogenicity were assessed with gray-scale US and vascularization with power Doppler US. All patients were treated conservatively. Clinical assessment was performed after 0, 3, and 6 months by using visual analogue scale (VAS) scores (0, no pain; 100, unbearable pain). The VAS scores were compared with the initial US findings, and analysis of variance was used for repeated measurements. RESULTS: Neovascularization was present in 30 of 55 painful tendons and in one of 25 asymptomatic tendons. The mean VAS scores at 0, 3, and 6 months, respectively, for tendons with neovascularization were 52, 26, and 20; those for tendons without neovascularization were 39, 19, and 18 (P =.15). Forty-eight painful and nine asymptomatic tendons were spindle shaped. The mean VAS scores at 0, 3, and 6 months, respectively, for the spindle-shaped tendons were 48, 25, and 20; those for normally shaped tendons were 33, 10, and 16 (P =.17). Thirty-five painful and four asymptomatic tendons were inhomogeneous. The mean VAS scores at 0, 3, and 6 months, respectively, for symptomatic inhomogeneous tendons were 54, 29, and 25; those for symptomatic homogeneous tendons were 32, 12, and 9 (P <.001). CONCLUSION: Although neovascularization is a specific sign for pain, it does not indicate an unfavorable outcome. Conversely, tendon inhomogeneity seems to be associated with an unfavorable outcome.     

Myxoid liposarcoma: magnetic resonance imaging appearances with clinical and histological correlation

Myxoid liposarcoma is the most common type of liposarcoma. The magnetic resonance imaging (MRI) features of this tumor were evaluated and correlated with its clinical and histological features in seven patients to determine under what circumstances the tumor should be considered in differential diagnosis and why its signal intensity differs from those of lipoma and lipoma-like (lipoblastic) liposarcoma. In all patients the tumor presented in a lower extremity (5 thigh, 2 calf) as a painless, slowly growing mass which had been present for several months to several years. MRI examination revealed the tumors to be encapsulated, noninfiltrating, and usually septated. On T₁-weighted sequences five of seven lesions (71%) showed lacy, amorphous, or linear foci of high signal within a low signal mass. These foci are believed to represent fat within the tumor and distinguish it from several other benign and malignant masses. If an indolent mass in a lower extremity demonstrates a predomiantly low signal with a few amorphous or linear high signal foci on T₁-weighted sequences, one should consider the possibility of myxoid liposarcoma even if it appears benign by all other criteria. Histologic evaluation showed that myxoid liposarcomas contain less than 10% mature fat, which accounts for their low signal on T₁-weighted sequences in contrast to the high signal of lipomas and lipoblastic liposarcomas.     

前列腺癌的MR波谱定量分析:与系统穿刺活检病理对照研究

目的　用MR波谱 (MRS)分析方法定量评价前列腺癌的代谢改变。方法　 18例超声引导下系统穿刺活检证实的前列腺癌患者在MRS代谢图上标记出活检取材位置 ,分别测量各个位置 (胆碱 肌酸 ) /枸橼酸盐 [(Cho Cre) /Cit]的比值。计算穿刺病理结果为癌处的 (Cho Cre) /Cit比值的平均值。结果　 18例患者共系统穿刺 2 0 4针 ,其中 10 6针为前列腺癌。此 10 6处 (Cho Cre) /Cit比值的平均值为 2 5 3± 1 0 2。肿瘤区域与非肿瘤区域的 (Cho Cre) /Cit比值差异有非常显著性意义 (P <0 0 1)。但肿瘤组与非肿瘤组的 (Cho Cre) /Cit比值有部分重叠 ,如果以 0 86为分界值 ,则两组之间有 10 9% (2 0 / 184 )的交叉。结论　前列腺癌的代谢改变可用MRS进行定量评价。     

Postmortem whole-body magnetic resonance imaging as an adjunct to autopsy: preliminary clinical experience

The purpose of this study was to evaluate whole-body magnetic resonance imaging (MRI) of cadavers as an adjunct to autopsy. Eight consecutive patients underwent both whole-body MRI and autopsy [either conventional (six), limited (one), or percutaneous (one)] within 24 hours of death. Comparison was made of major and minor abnormalities and predicted cause of death recorded by independent readers at both MRI and autopsy. Major discrepancies between the recorded primary cause of death at imaging and autopsy occurred in five (5) patients. These included a myocardial infarction found at autopsy alone, bowel infarction and portal venous gas found at MRI alone, and aortic dissection and occipital infarct found at MRI alone in a patient on whom only limited autopsy was performed. Postmortem MRI may represent a useful adjunct to autopsy, particularly in patients in whom autopsy is limited due to patient/family consent, inoculation risks, and ethnic doctrines.     

Hypointensities in the brain on T2*-weighted gradient-echo magnetic resonance imaging

The objectives of this review are to present various entities that can result in hypointensity on brain T2*-weighted gradient-echo (GE) images and to show the usefulness of this sequence. There are six etiologies, resulting in hypointensity on T2*-weighted GE images, ie, the presence of hemosiderin, deoxyhemogrobin, ferritin, calcium, other metals, and air. This sequence is sensitive to magnetic susceptibility effect and useful for detecting some kinds of small brain lesions and for differential diagnosis in some special conditions.     

Effect of gender on in vivo cartilage magnetic resonance imaging T2 mapping

PURPOSE: To determine if gender is a significant variable for in vivo magnetic resonance imaging (MRI) T2-mapping of knee articular cartilage in young asymptomatic volunteers. MATERIALS AND METHODS: Cartilage MRI T2 mapping was performed in a young healthy population consisting of seven male and 10 female volunteers, 22 to 29 years of age. High-resolution in vivo T2 maps were obtained of patellar, tibial, and weight-bearing femoral articular cartilage. Spatial dependency of cartilage T2 between groups was evaluated through a comparison of cartilage T2 as a function of normalized distance from bone. RESULTS: Bulk cartilage T2 values were similar at all three anatomic sites, and between male and female volunteers. All volunteers demonstrated similar spatial variation in cartilage MRI T2 values, with a minimum located in the radial zone and increasing T2 values toward the articular surface. There was no difference in spatial dependency of cartilage T2 between males and females. CONCLUSION: In young, healthy volunteers, the magnitude and spatial dependency of cartilage T2 does not differ with gender.     

In vivo neurochemistry with emission tomography and magnetic resonance spectroscopy: clinical applications

The assessment of neurochemical processes in vivo has received much attention in the past decade as techniques such as positron or single photon emission tomography (PET and SPET), and magnetic resonance spectroscopy (MRS) have become more available. With PET and SPET, basic processes, such as blood flow and oxygen or glucose metabolism, can be regionally assessed, along with more specific functions such as the production, release, and reuptake of neurotransmitters and their occupancy of specific receptors. At the same time, MRS can reveal changes in concentration of several hydrogenate compounds in the brain. All these methods have been extensively applied for research in neurology, and some applications have reached the clinical level, namely for the study of degenerative diseases, motor-neuron diseases, movement disorders, cerebrovascular diseases, and epilepsy. This article focuses on the most relevant information that can be obtained with these complementary techniques to help clinicians in the assessment of neurological diseases.     

3T magnetic resonance neurography of pudendal nerve with cadaveric dissection correlation

AIMTo evaluate the pudendal nerve segments that could be identified on magnetic resonance neurography (MRN) before and after surgical marking of different nerve segments.METHODSThe hypothesis for this study was that pudendal nerve and its branches would be more easily seen after the surgical nerve marking. Institutional board approval was obtained. One male and one female cadaver pelvis were obtained from the anatomy board and were scanned using 3 Tesla MRI scanner using MR neurography sequences. All possible pudendal nerve branches were identified. The cadavers were then sent to the autopsy lab and were surgically dissected by a peripheral nerve surgeon and an anatomist to identify the pudendal nerve branches. Radiological markers were placed along the course of the pudendal nerve and its branches. The cadavers were then closed and rescanned using the same MRN protocol as the pre-marking scan. The remaining pudendal nerve branches were attempted to be identified using the radiological markers. All scans were read by an experienced musculoskeletal radiologist.RESULTSThe pre-marking MR Neurography scans clearly showed the pudendal nerve at its exit from the lumbosacral plexus in the sciatic notch, at the level of the ischial spine and in the Alcock’s Canal in both cadavers. Additionally, the right hemorrhoidal branch could be identified in the male pelvis cadaver. The perineal and distal genital branches could not be identified. On post-marking scans, the markers were used as identifiable structures. The location of the perineal branch, the hemorroidal branch and the dorsal nerve to penis (in male cadaver)/clitoris (in female cadaver) could be seen. However, the visualization of these branches was suboptimal. The contralateral corresponding nerves were poorly seen despite marking on the surgical side. The nerve was best seen on axial T1W and T2W SPAIR images. The proximal segment could be seen well on 3D DW PSIF sequence. T2W SPACE was not very useful in visualization of this small nerve or its branches.CONCLUSIONProximal pudendal nerve is easily seen on MR neurography, however it is not possible to identify distal branches of the pudendal nerve even after surgical marking.