Utility of positron emission tomography-magnetic resonance imaging in musculoskeletal imaging

Differentiation between neoplastic and nonneoplastic conditions magnetic resonance imaging (MRI) has established itself as one of the key clinical tools in evaluation of musculoskeletal pathology. However, MRI still has several key limitations which require supplemental information from additional modalities to complete evaluation of various disorders. This has led to the development hybrid positron emission tomography (PET)-MRI which is rapidly evolving to address key clinical questions by using the morphological strengths of MRI and functional information of PET imaging. In this article, we aim to review physical principles and techniques of PET-MRI and discuss clinical utility of functional information obtained from PET imaging and structural information obtained from MRI imaging for the evaluation of musculoskeletal pathology. More specifically, this review highlights the role of PET-MRI in musculoskeletal oncology including initial diagnosis and staging, treatment planning and post-treatment follow-up. Also we will review utility of PET-MRI in evaluating musculoskeletal infections (especially in the immunocompromised and diabetics) and inflammatory condition. Additionally, common pitfalls of PET-MRI will be addressed.     

Recurrent ovarian endodermal sinus tumor: demonstration by computed tomography,magnetic resonance imaging,and positron emission tomography

We report a case of recurrent endodermal sinus tumor.of the ovary that was identified and/or clearly depicted by computed tomography, magnetic resonance imaging, and positron emission tomography. The potential roles of various imaging modalities in the detection of recurrent endodermal sinus tumor are discussed.     

Psoas muscle metastasis from cervical carcinoma: Correlation and comparison of diagnostic features on FDG-PET/CT and diffusion-weighted MRI

Psoas muscle metastasis, though rare, is the commonest site of skeletal muscle involvement in cervical carcinoma. The appropriate clinical management of this condition, particularly of the pain related to malignant psoas syndrome, is still evolving and the diagnostic features on conventional morphological imaging modalities are often non specific, with the differential diagnosis lying between sarcoma, hematoma, and abscess. In this report, a comparison of various morphofunctional imaging modalities was made. Fluorodeoxyglucose-positron emission tomography (FDG-PET)/computed tomography (CT) was the first to suspect disease involvement of the psoas muscle, demonstrating intense FDG uptake (compared with the contralateral muscle), while ultrasound showed heterogeneous echotexture, and magnetic resonance imaging (MRI) showed subtle altered signal intensity in the right psoas muscle. Both anatomical imaging modalities and non contrast CT of the PET-CT examination demonstrated a bulky psoas muscle, without any focal abnormality. On diffusion-weighted imaging of MRI (DWI-MRI), restricted diffusion of the involved muscle was an important observation. The psoas muscle metastatic involvement was proven histopathologically. Thus, enhanced glucose metabolism and restricted diffusion in the newer non-invasive molecular imaging modalities (e.g., PET/CT and DWI-MRI) could serve as valuable adjunctive parameters in diagnosing this entity in the absence of a focal abnormality in the anatomical modalities. In the treatment response monitoring scenario, FDG-PET/CT demonstrated near complete resolution following administration of 3 cycles of systemic chemotherapy and local external radiotherapy.     

胸腺增生的影像学研究进展

胸腺增生是胸腺常见良性病变,分为真性增生和淋巴滤泡增生,多伴有重症肌无力等自身免疫性疾病。影像学检查不仅可以反映胸腺形态的变化,还可以定量评估胸腺的大小、密度及胸腺内脂肪含量,是评估胸腺增生的重要工具。目前胸腺增生的影像学检查包括CT、MRI及PET/CT等,尚无统一的影像诊断标准。就胸腺的发育、胸腺增生的临床特征、影像学进展及鉴别诊断进行综述。     

Whole-body MRI and PET-CT in the management of cancer patients

Mortality rate, prognosis, and treatment outcome of cancer patients depend strongly on the detection of malignancy at an early stage and efficient monitoring of the disease. Multimodality diagnostic approaches are now widely applied for tumor detection, staging, and follow-up. However, the introduction of whole-body imaging modalities into clinical practice has substantially expanded diagnostic options. PET-CT has increased diagnostic accuracy by providing “anatometabolic” information by fusing tumor glucose-uptake measures from the PET examination and accurate delineation of anatomical structures given by spiral CT. Since PET-CT is associated with high doses of ionizing radiation, it is used in mainly tumor staging and screening within the scope of tertiary prevention. Here promising results have been reported for various tumor entities. MRI provides excellent tissue contrast, detailed morphological information and lack of ionizing radiation. MRI has been employed for the assessment of focal pathologies in specific anatomical regions. Whole-body MRI scanners using multiple receiver channels with parallel acquisition techniques now allow tumor screening from head to toe within substantially shorter examination times and without compromises in image resolution. We report our experience with these two novel techniques and discuss their benefits and drawbacks in terms of systemic tumor screening.     

椎体淋巴瘤MRI及PET临床应用价值

目的探讨椎体淋巴瘤MRI及正电子发射体层成像(PET)的影像特征及临床应用价值。资料与方法回顾性分析经病理证实的15例椎体淋巴瘤患者的MRI和PET表现,原发性骨淋巴瘤6例,继发性9例。结果MRI:原发性6例均为单一椎体压缩性骨折伴局部硬膜外和/或椎体旁软组织肿块,软组织范围超过病变椎体;继发性9例均为多椎体压缩性改变,7例伴硬膜外和/或椎体旁软组织肿块。椎体病变T1WI呈等或混杂信号,T2WI呈稍高信号。软组织肿块T1WI呈等/低信号,T2WI呈稍高信号,明显均匀强化5例,轻度均匀强化8例。PET:原发性6例均为术后PET检查,1例术后2个月显示局部复发,5例无异常;继发性9例(术前6例、术后3例)PET显示多椎体、淋巴结及脾葡萄糖代谢异常增高。结论椎体原发性淋巴瘤多为单椎体病变;继发性常为多椎体受累,两者均可伴硬膜外和/或椎体旁软组织肿块。椎体淋巴瘤MRI、PET表现无特异性,MRI能清晰显示椎管内病灶与脊髓的关系,PET对鉴别原发性与继发性淋巴瘤有重要价值。     

99mTechnetium HMPAO imaging in children with the Sturge-Weber syndrome: a study of nine cases with CT and MRI correlation

Demonstration of the full extent of abnormality in patients with the Sturge-Weber syndrome (SWS) is important for prognosis and in planning surgery to remove the seizure focus. We compared single-photon emission computed tomography (SPECT), MRI and CT in nine children under the age of 4 years with seizures as part of SWS, in an attempt to determine the optimal method of imaging in different clinical settings. Seven unilateral and two bilateral cases were studied by interictal ^99mtechnetium hexamethylpropyleneamineoxime (HMPAO) SPECT, and contrast-enhanced CT and MRI, giving information on 11 abnormal hemispheres. All imaging modalities showed abnormalities in every child. Perfusion imaging showed focal regions of decreased uptake in 9 of 11 (82 %) abnormal hemispheres and demonstrated a widespread decrease but no focal defect in 2; it also revealed crossed cerebellar diaschisis in 2 cases. CT demonstrated typical gyriform calcification in 9 of 11 (82 %) affected hemispheres. Contrast-enhanced MRI showed more extensive involvement than contrast-enhanced CT in 5 of 11 (45 %) cases. The area of hypoperfusion shown by SPECT was smaller than the area of contrast enhancement on MRI in 6 of 11 cases (55 %), comparable in 3 (27 %) and larger in 2 cases (18 %). CT is sufficient to confirm the clinical diagnosis of SWS, but MRI frequently shows more extensive abnormal areas. ^99mTc HMPAO imaging is a useful addition when it is important to know the full extent of the disease, for example prior to surgery. It is likely to detect areas of hypoperfusion, representing ischaemic regions, which may act as an epileptogenic focus and may not be shown by CT or MRI. Received: 31 August 1995 Accepted: 27 March 1996     

Advancements of molecular imaging and radiomics in pancreatic carcinoma

Despite the recent progress of medical technology in the diagnosis and treatment of tumors, pancreatic carcinoma remains one of the most malignant tumors, with extremely poor prognosis partly due to the difficulty in early and accurate imaging evaluation. This paper focuses on the research progress of magnetic resonance imaging, nuclear medicine molecular imaging and radiomics in the diagnosis of pancreatic carcinoma. We also briefly described the achievements of our team in this field, to facilitate future research and explore new technologies to optimize diagnosis of pancreatic carcinoma.     

多模式分子影像PET-MRI的研究进展

PET-CT已成为当今恶性肿瘤诊断、分期及疗效评价必不可少的工具,但是,MRI具有比CT更好的软组织分辨力,还可提供多种生理功能、多序列和多参数成像,且无放射性损伤,其与PET提供的分子信息互补、融合,有望成为新的双模式显像工具,在基础和临床研究中将起着至关重要的作用.然而PET与MRI结合在技术上具有很多挑战,近几年...     

锰中毒的神经影像学研究进展

近二十年来,医学影像学对临床医学的影响非常深刻,在疾病的诊断和治疗中的作用是具革命性的。核磁共振成像(MRI)、正电子发射断层摄影(PET)和单光子发射断层摄影(SPECT)等神经影像学方法在最近十年中已应用于锰中毒和其神经毒理学研究。MRI T1加权图像信号强度增加会反映锰的沉积,功能神经影像学如:PET、SPECT,能早期发现黑质纹状体多巴胺系统的异常,因此MRI、PET、SPECT对于锰中毒的诊断非常重要。     

Diagnostic imaging of pediatric hematogenous osteomyelitis: lessons learned from a multi-modality approach

Pediatric hematogenous osteomyelitis may present highly variable radiological expression, which is influenced by the age and condition of the patient, the virulence of the causative agent, the stage of the disease, or the selected imaging tool. Given the multiplicity of available modalities and the multi-faceted nature of the process, purposeful imaging of pediatric hematogenous osteomyelitis may be difficult. In order to avoid diagnostic delays and complications, familiarity with the variable expression of the disease and assumption of the potentialities, roles and limitations of the various imaging modalities is required. In this pictorial essay we review, illustrate and discuss, in a multi-modality approach, the various radiological patterns that may be found in pediatric hematogenous osteomyelitis, with emphasis on strategies, staging, uncommon distribution patterns, and differential diagnosis.     

MRI全景矩阵成像技术在全身骨转移瘤诊断中的价值

目的 探讨全景矩阵成像(TIM)技术对全身骨转移瘤的诊断价值.资料与方法 对25例恶性肿瘤患者采用单光子发射计算机断层显像(SPECT)进行全身骨扫描与TIM技术全身MRI扫描,对两种检查方法进行评价比较.结果 25例中,MRI-TIM及SPECT共检出23例63个病灶,其中恶性54个、良性9个,TIM正确诊断50个转移瘤病灶,敏感度为93%(50/54),特异度为67%(6/9),阳性预测值为94%(50/53),阴性预测值为60%(6/10).SPECT正确诊断47个病灶,敏感度为87%(47/54),特异度为56%(5/9),阳性预测值为92%(47/51),阴性预测值为42%(5/12).两种检查方法的敏感度与特异度之间的差异均无统计学意义(P值分别为0.077和0.643).全身MRI的诊断准确率为89%(56/63),SPECT的诊断准确率为83%(52/63),两者之间的差异有统计学意义(P=0.000).结论 SPECT与TIM能有效地检出全身骨转移癌灶,但TIM对骨髓病变有较高的空间分辨率,比SPECT的诊断正确率更高.     

Imaging and interventions in hilar cholangiocarcinoma: A review

Hilar cholangiocarcinoma is a common malignant tumor of the biliary tree. It has poor prognosis with very low 5-year survival rates. Various imaging modalities are available for detection and staging of the hilar cholangiocarcinoma. Although ultrasonography is the initial investigation of choice, imaging with contrast enhanced computed tomography scan or magnetic resonance imaging is needed prior to management. Surgery is curative wherever possible. Radiological interventions play a role in operable patients in theform of biliary drainage and/or portal vein embolization. In inoperable cases, palliative interventions include biliary drainage, biliary stenting and intra-biliary palliative treatment techniques. Complete knowledge of application of various imaging modalities available and about the possible radiological interventions is important for a radiologist to play a critical role in appropriate management of such patients.We review the various imaging techniques and appearances of hilar cholangiocarcinoma and the possible radiological interventions.     

Whole-body MRI at high field: technical limits and clinical potential

This review seeks to clarify the most important implications of higher magnetic field strength for clinical examinations of the whole body. An overview is provided on the resulting advantages and disadvantages for anatomical, functional and biochemical magnetic resonance examinations in different regions of the body. It is demonstrated that susceptibility-dependent imaging, chemical shift selective (e.g., fat-suppressed) imaging, and spectroscopic techniques clearly gain from higher field strength. Problems due to shorter wavelength and higher radio frequency energy deposition at higher field strength are reported, especially in examinations of the body trunk. Thorax examinations provided sufficient homogeneity of the radio frequency field for common examination techniques in most cases, whereas abdominal and pelvic imaging was often hampered by undesired dielectric effects. Currently available and potential future strategies to overcome related limitations are discussed. Whole-body MRI at higher field strength currently leads to clearly improved image quality using a variety of established sequence types and for examination of many body regions. But some major problems at higher field strength have to be solved before high-field magnetic resonance systems can really replace the well-established and technically developed magnetic resonance systems operating at 1.5 T for each clinical application.     

Imaging of bone metastasis: An update

Early detection of skeletal metastasis is critical for accurate staging and optimal treatment. This paper briefly reviews our current understanding of the biological mechanisms through which tumours metastasise to bone and describes the available imaging methods to diagnose bone metastasis and monitor response to treatment. Among the various imaging modalities currently available for imaging skeletal metastasis, hybrid techniques which fuse morphological and functional data are the most sensitive and specific, and positron emission tomography (PET)/computed tomography and PET/magnetic resonance imaging will almost certainly continue to evolve and become increasingly important in this regard.     

Infantile fibrosarcoma: radiological and clinical features

Two cases of infantile fibrosarcoma are described. This rare childhood malignancy of mesodermal origin usually affects the lower limbs, as it did in both of our cases. Previously, the only treatment option available involved some form of radical and often mutilating surgery. More recently, combination chemotherapy has given good results, with the effect that various imaging modalities have become important in assessing both the initial extent of disease and the response to treatment. Computed tomography has the advantage of demonstrating the amount of osseous involvement, but at the expense of a considerable dose of ionizing radiation. On the other hand, magnetic resonance imaging, with its multiplanar capacity, gives superior demonstration of breaching of tissue planes, which has important implications for planning of surgery. However, as in other soft tissue tumours, changes in signal characteristics with treatment have proved less specific than was originally anticipated.     

术前影像检查在预测肝癌微血管侵犯中的研究进展

微血管侵犯(MVI)是肝癌术后复发及转移独立预测因子之一,目前只能经病理学确诊,但随着影像技术的发展,超声、CT、MRI、PET-CT/MRI等技术逐渐用于肝癌MVI的预测,即通过对一些能够反映肿瘤内部微环境、细胞功能与物质成分以及血流动力学等方面的定量参数的测量得到实现。就术前影像检查预测肝癌MVI的研究进展进行综述。     

Pre- and Post-Treatment Imaging of Primary Central Nervous System Tumors in the Molecular and Genetic Era

Recent advances in the molecular and genetic characterization of central nervous system (CNS) tumors have ushered in a new era of tumor classification, diagnosis, and prognostic assessment. In this emerging and rapidly evolving molecular genetic era, imaging plays a critical role in the preoperative diagnosis and surgical planning, molecular marker prediction, targeted treatment planning, and post-therapy assessment of CNS tumors. This review provides an overview of the current imaging methods relevant to the molecular genetic classification of CNS tumors. Specifically, we focused on 1) the correlates between imaging features and specific molecular genetic markers and 2) the post-therapy imaging used for therapeutic assessment.     

Neuroradiological findings in primary progressive aphasia: CT,MRI and cerebral perfusion SPECT

Primary progressive aphasia (PPA) is defined as progressive decline in language for 2 or more years with preservation of activities of daily living and general cognitive functions. Whereas the clinical features of this syndrome have been well documented, the neuroradiological findings have not been studied systematically. We studied 13 patients with PPA retrospectively: 10 underwent CT, 12 MRI and 12 cerebral perfusion studies using^99mTc-HMPAO SPECT. CT and MR images were scored for focal atrophy by two independent assessors. Initial qualitative assessment of SPECT images was confirmed by quantitative analysis. CT was normal in 5 patients. Focal atrophy, affecting predominantly the left temporal lobe, was seen in 4 of 10 patients on CT, and 10 of 12 on MRI. Atrophy was localised primarily to the superior and middle temporal gyri on MRI. All 12 patients who underwent SPECT had unilateral temporal lobe perfusion defects, in 2 patients of whom MRI was normal. CT is relatively insensitive to focal abnormalities in PPA; MRI and SPECT are the imaging modalities of choice. MRI allows accurate, specific localisation of atrophy within the temporal neocortex. SPECT may reveal a functional decrease in cerebral perfusion prior to establishment of structural change.     

Imaging of liver transplantation

Liver transplantation (LT) is the treatment of choice for end-stage chronic liver disease, fulminant liver failure and early stage hepatocellular carcinoma. As discussed in this review, state-of-the-art imaging modalities including ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI) play a pivotal role in the selection of patients and donors, as well as in early detection of those complications at risk of impairing graft function and/or survival. We also illustrate main imaging findings related to the wide spectrum of clinical problems raised by LT.