Moderne MR-Verfahren zur Beurteilung der Tumorresponse

Magnetic resonance imaging (MRI) is a mainstay in oncological imaging with respect to tumor detection, characterization and treatment monitoring. Besides quantifying metric changes of tumor tissue, a wide range of different other surrogate parameters of therapy response can be imaged and quantified by MRI. Early monitoring of treatment success is critical both for medical and economical reasons specifically with more expensive target-specific drugs entering the clinical arena. Dynamic contrast-enhanced (DCE) and steady state MRI can help to assess tumor perfusion and vessel permeability. The cellular state of tissue can be measured by diffusion-weighted imaging (DWI) and metabolic changes can be monitored by MR spectroscopy (MRS). New target-specific contrast agents potentially allow selective imaging of apoptotic events.This review aims to give a brief overview of new MR-based imaging approaches to assess tumor response to new target-specific therapy regimes, with special emphasis on anti-angiogenic and antivascular treatment effects.     

Relationship between histologic thickness of tongue carcinoma and thickness estimated from preoperative MRI

Several studies have shown that the thickness of tongue carcinoma is related to prognosis and to the likelihood of cervical node metastases. We investigated whether preoperative estimates of tumor thickness and volume, as determined from magnetic resonance imaging (MRI), correlated with histologic thickness and might therefore predict the presence of neck metastases. We assessed relationships between histologic tumor thickness and MRI tumor thickness and volume in a retrospective series of 33 patients with squamous cell carcinoma of the tongue. Thicknesses were determined by direct measurement and by considering corrections for ulceration or tumor vegetation (reconstructed thickness). Relationships between MRI thickness and the presence or absence of homolateral and contralateral nodal metastases were also investigated. We found that MRI thicknesses correlated strongly and directly with histologic tumor thicknesses, although mean MRI thicknesses were significantly greater than histologic thicknesses. MRI thicknesses were significantly greater in patients with contralateral neck involvement than in those with no neck involvement. We conclude that MRI provides an accurate and reproducible means of estimating the thickness of tongue carcinomas, paving the way for further studies on more extensive series of patients to determine whether preoperatively determined MRI thickness can reliably predict homolateral and bilateral neck involvement.     

Differentialdiagnose fokaler Nierenläsionen in CT und MRT

The great majority of renal masses are found incidentally as a result of the use of ultrasonography, computed tomography (CT) and magnetic resonance imaging (MRI). If ultrasonography is not diagnostic CT or MRI should be initiated to differentiate lesions of the kidney that need surgical intervention from those that do not and from those that need follow-up examinations.Cystic renal masses are characterized by using the Bosniak classification, including category IIF. In solid lesions of the kidney first non-surgical lesions as well as lymphoma, renal infarction and nephritis should be excluded. Identifying fatty components in renal lesions is very important because in angiomyolipoma they are almost always present.CT and MRI are exellent for tumor detection. Careful evaluation of imaging finding combined with the patient′s history should assist the radiologist in making the proper diagnosis or recommending the appropriate treatment in most cases.This article provides a review about renal masses, the imaging methods for their evaluation and their characteristic features at CT and MR imaging. Different lesions are demonstrated like xantogranulomatous pyelonephritis, acute pyelonephritis, renal infarction, lymphoma, angiomyolipoma, renal oncocytoma, cystic lesion and polycystic disease the kidney, echinococcosis, renal cystadenoma, metastases, renal cell carcinoma (RCC), and multiple bilateral RCC in patients with Hippel-Lindau-Syndrome.This article should help to differentiate complex cystic lesions of the kidney by using the Bosniak-classification, especially Bosniak Category IIF. Solid masses should be characterized and the major question to be answered is whether the mass represents a surgical or nonsurgical lesion or if follow-up studies are necessary.     

Weichteiltumoren

Only approximately 1% of soft tissue tumors are malignant. Potentially malignant lesions can be recognized by ultrasound and submitted for magnetic resonance imaging (MRI). Radiography can supply valuable additional information. The MRI examination is the imaging reference standard for soft tissue tumors and also serves as local staging modality. Lesions which are indeterminate in MRI, or in which therapy is dependent on histology results, should be biopsied. Referral to a reference center is recommended. The multitude of soft tissue tumor entities are classified according to the World Health Organization (WHO) system (latest version 2013). Some tumors show characteristic locations and MRI morphology. Sarcoma staging by imaging is influenced by the size and site in comparison to the surface fascia. International standards must be adhered to: decisive for the patient is in particular the care by an experienced interdisciplinary tumor team.     

Magnetic resonance imaging of bone marrow disorders

The sensitivity of MRI to marrow infiltration together with the ability to perform multiplanar imaging allows evaluation of the bone marrow in a manner that has never been feasible before. The clinical impact of this has yet to be fully realized. However, detection of focal marrow infiltration by MRI with concurrently normal conventional imaging studies has important clinical implications for staging and therapy. Proper staging of marrow-based neoplasms such as leukemia and lymphoma is fundamental to the determination of treatment and prognosis. MRI can be used to increase diagnostic certainty when a question exists concerning primary or metastatic marrow disease when other imaging studies are inconclusive. Chemical shift imaging may further improve the sensitivity and clinical utility of magnetic resonance imaging in patients with hematologic disorders involving the bone marrow.     

Magnetic resonance imaging of neuroblastoma with a 0.15-T magnet

Magnetic resonance imaging (MRI) in nine children with neuroblastoma showed that MRI can effectively demonstrate primary and metastatic disease and aid in predicting tumor resectability. MRI can show changes in tumor size and intensity in response to chemotherapy or radiation therapy. Neuroblastomas have an image intensity much lower than that of liver and muscle on inversion-recovery scans. On spin-echo 500/30 scans, the tumors have a greater intensity than muscle and a similar or slightly greater intensity than liver. On spin-echo 1000/60 scans, they are always of greater intensity than liver or muscle. At this stage, the overall accuracy of MRI as compared with other imaging methods is not known.     

Diagnostic value of ultrasonography and other imaging examinations in patients with intramuscular myxoma: A case series and literature review

Intramuscular myxoma (IM) is a rare benign soft tumor of mesenchymal origin. Most IMs are located in the large skeletal muscles, and they are typically painless slow-growing masses that are detected incidentally. Surgical excision of IM usually has a good prognosis. Because of its rarity, diagnosing IM via imaging modalities such as ultrasonography (US), computed tomography, positron emission tomography/computed tomography, and magnetic resonance imaging (MRI) can be challenging. Relevant literature and cases were selected as per the inclusion and exclusion criteria. Characteristic imaging findings include a well-defined, ovoid mass with regular morphology and an orientation whereby the long axis is aligned with the course of muscle fibers. In US, IMs exhibit solid cystic mixed echo without obvious blood flow signal. However, MRI reveals hypointensity on T1-weighted images and hyperintensity on T2-weighted images with mild and patchy enhancement. In cases of suspected or potential IM, US and MRI can provide excellent resolution at a reasonable cost. This report aims to improve the recognition rate of IM. Herein, we review imaging characteristics that can contribute to the differential diagnosis of IM.     

Advanced magnetic resonance imaging findings in salivary gland tumors

Salivary gland tumors (SGTs) make up a small portion (approximately 5%) of all head and neck tumors. Most of them are located in the parotid glands, while they are less frequently located in the submandibular glands, minor salivary glands or sublingual gland. The incidence of malignant or benign tumors (BTs) in the salivary glands varies according to the salivary gland from which they originate. While most of those detected in the parotid gland tend to be benign, the incidence of malignancy increases in other glands. The use of magnetic resonance imaging (MRI) in the diagnosis of SGTs is increasing every day. While conventional sequences provide sufficient data on the presence, localization, extent and number of the tumor, they are insufficient for tumor specification. With the widespread use of advanced techniques such as diffusion-weighted imaging, semi-quantitative and quantitative perfusion MRI, studies and data have been published on the differentiation of malignant or BTs and the specificity of their subtypes. With diffusion MRI, differentiation can be made by utilizing the cellularity and microstructural properties of tumors. For example, SGTs such as high cellular Warthin’s tumor (WT) or lymphoma on diffusion MRI have been reported to have significantly lower apparent diffusion values than other tumors. Contrast agent uptake and wash-out levels of tumors can be detected with semi-quantitative perfusion MRI. For example, it is reported that almost all of the pleomorphic adenomas show an increasing enhancement time intensity curve and do not wash-out. On quantitative perfusion MRI studies using perfusion parameters such as Ktrans, Kep, and Ve, it is reported that WTs can show higher Kep and lower Ve values than other tumors. In this study, the contribution of advanced MRI to the diagnosis and differential diagnosis of SGTs will be reviewed.     

MR imaging in the assessment of lung cancer patients: primary lung cancer staging, evaluation of therapeutic effect and diagnosis of recurrent tumor

Magnetic resonance imaging and computed tomography were compared in a prospective study of 137 lung cancer patients proved by surgery or autopsy for determining the staging, evaluation of therapeutic effect and diagnosis of recurrent tumor. 1. Lung cancer staging In peripheral lung cancer, T1 and T2 relaxation times of the tumors before operation have some correlation with those of operated specimens. These relaxation times, however, are of limited nodule characterization. Hilar mass and adjacent pulmonary consolidation (obstructive pneumonia or collapse) can be distinguished on T2-weighted image (77%) and Gd-DTPA enhanced image (80%). Therefore these images help in distinguishing tumor from peripheral lung disease. In the diagnosis of tumor invasion to the heart and great vessels, MRI is superior to CT because MRI can be helpful in distinguishing true mass from heart and great vessels. As for the chest wall, MRI is more useful than CT in detecting tumor invasion especially to the thoracic inlet and superior regions. In the diagnosis of mediastinal and hilar lymphadenopathy, MRI is equivalent or slightly inferior to CT, but MRI can easily demonstrate the lymphadenopathy at subcarinal region on coronal image. 2. Evaluation of therapeutic effect in lung cancer patients treated by radiation and chemotherapy MRI patterns of therapeutic effect was divided into 3 types. It is suggested that there is some correlation between these patterns and histologic types. MRI can easily demonstrate necrotic area on T2-weighted and Gd-DTPA enhanced images. 3. Diagnosis of recurrent tumor in treated lung cancer Concerning detecting recurrent tumor after surgery or irradiation, and delineating tumor from radiation pneumonitis, T2-weighted and Gd-DTPA enhanced images are of clinical value.     

Magnetic resonance imaging of musculoskeletal tumors: skeletal and soft tissue masses

The purpose of this article is to review the MRI characteristics of musculoskeletal tumors, including skeletal and soft tissue masses. MRI has become the premier imaging modality for the evaluation of musculoskeletal tumors because of its excellent soft tissue contrast, its sensitivity to bone marrow and soft tissue edema, and its multiple imaging planes. In a substantial subset of cases, MRI can provide a diagnosis or a short differential diagnosis, while certain tumors have no distinguishing signal characteristics. MRI of musculoskeletal tumors can also be challenging, because the MRI appearance of certain lesions can be misleading, and a knowledge of the instances in which MRI over- and underestimates the malignancy of lesions is invaluable. The importance of correct protocols for tumor evaluation, both in diagnosis and in pre-operative evaluation, are discussed. Common pitfalls that may over- or underestimate the aggresivity of lesions will be highlighted, as will the role of gadolinium enhancement in the evaluation of lesions. The MRI appearance of common benign and malignant muculoskeletal lesions will be illustrated.     

Imaging of cancer of the uterine cervix

Recently, magnetic resonance imaging (MRI) and transrectal or transvaginal ultrasound (TRUS, TVUS) had an important place in imaging techniques of cervical carcinomas and raise the question of modifying the imaging strategies. For the diagnosis of primitive tumor, those techniques cannot take the place of clinical examination and gross examination. In the assessment of parametrial involvement, TRUS which has better accuracy than clinical examination, and MRI which is considered as the most accurate technique, have an important role to play. In the follow-up and the detection of recurrences, MRI is actually considered as the best imaging technique. The authors, according to recent data in literature and their own experience, present basic concepts of imaging strategies for staging and follow-up of cervical carcinomas.     

Tumor-induced osteomalacia – Current imaging modalities and a systematic approach for tumor localization

Paraneoplastic syndromes are symptom complexes that cannot be readily explained by local or distant spread of the tumor. They can occur due to hormone production, autoimmunity or other biologically active products produced by the tumor, etc. Tumor induced osteomalacia is a rare paraneoplastic syndrome in which the manifestation is mainly musculoskeletal such as bone pain, fractures and muscle weakness as a consequence of elaboration of fibroblast growth factor 23 (FGF23) by the tumor.Most of these tumors are solitary and small and hence localization of these tumors is often challenging. This review summarizes the various anatomic imaging modalities such as plain radiographs, computed tomography (CT), and magnetic resonance imaging (MRI) and nuclear medicine imaging techniques in the evaluation of these tumors.     

儿童臀部硬纤维瘤的影像表现

目的:探讨臀部硬纤维瘤的超声、CT、MRI表现特征。材料和方法:搜集10例经手术病理证实的儿童臀部硬纤维瘤病例,均行超声、CT平扫及增强扫描,5例行MRI检查,分析其影像学特点。结果:臀部硬纤维瘤主要累及臀部肌肉、筋膜、骨膜等,呈浸润性生长,易复发。超声表现为不规则低回声肿块。CT表现为低密度软组织肿块(9例),等高密度肿块(1例),强化程度不等。MRI表现为臀部肿块,T1WI等低信号,T2WI多为稍高信号夹杂斑片低信号(3例),或等低信号(2例),增强后可见不均匀强化。结论:超声、CT及MRI检查可显示硬纤维瘤的大小、形态;MRI能从多个切面显示肿瘤范围以及周围组织受侵情况,并可推断组织成分,为临床治疗提供重要信息。     

Ultrasound evaluation of soft tissue tumors.

Because of its availability, ultrasound should be the preferred initial modality for the evaluation of palpable superficial masses. Most ultrasound units are equipped with high frequency probes that allow superficial focalization. The differential diagnosis of soft tissue masses and the sonographic features of some benign and malignant soft tissue lesions are reviewed in this article. After an initial ultrasound evaluation confirming the presence of a tumor, the need for and the role of other imaging modalities can be determined. In selected cases ultrasound may obviate the need for further imaging. MRI and CT should be reserved for cases in which sonography fails to establish a specific diagnosis or to demonstrate the limits of the soft tissue mass.     

Magnetic resonance first-pass myocardial perfusion imaging: clinical validation and future applications.

Clinical studies suggest that magnetic resonance first-pass (MRFP) perfusion imaging is comparable to current diagnostic tests that are used clinically for the assessment of myocardial perfusion. In addition, magnetic resonance imaging (MRI) perfusion imaging is a noninvasive method for determining myocardial blood flow. The spatial resolution (in-plane spatial resolution < 3 mm) is sufficient to differentiate between subendocardial perfusion and subepicardial perfusion. The measurement can be repeated regularly without any adverse effects for the patient. MRI perfusion measurements can be combined with the evaluation of global function and regional wall thickening. Currently, there is no other imaging technique that offers similar advantages. The MRI perfusion measurements can be carried out during baseline conditions and during maximal hyperemia induced with either adenosine or dipyridamole. The ratio of the measured myocardial blood flows provides an estimate of the absolute and relative myocardial perfusion reserve. The perfusion reserve determined with MRFP imaging is a quantitative measure for the assessment of the collateral-dependent myocardial flow. Based on the available data using MRFP perfusion imaging, the current clinical first-line perfusion imaging tests are going to be challenged in the near future. J. Magn. Reson. Imaging 1999;10:676-685.     

Comparison of magnetic resonance imaging and multidetector computed tomography for evaluating intraductal tumor extension of breast cancer

Magnetic resonance imaging (MRI) and computed tomography (CT) can be used for pretreatment evaluation of intraductal tumor extension of breast cancer. Images of intraductal tumor extension obtained by MRI and multidetector CT (MDCT) are shown to illustrate the similarities and differences in the imaging features of these two techniques. MRI is an excellent tool and MDCT is a fair one for evaluating intraductal tumor extension of breast cancer.     

Imaging strategies for MRI of the pelvis

Appropriate patient triage of pelvic diseases depends upon a problem-solving approach as outlined in this article. Whether MRI is chosen as an adjunct to US or CT or as the primary modality, as in the staging of malignancy, imaging strategies for pelvic MRI can be tailored to the organ of interest and to the clinical question being asked.     

肝细胞癌射频消融术后疗效的CT及MRI评价研究现状

射频消融（RFA）是一种使肿瘤组织发生凝固性坏死的治疗手段。肝细胞癌RFA术后可能具有完全消融、肿瘤残余、局部肿瘤进展及新发肿瘤等不同的治疗效果。CT、MRI及功能MRI是评价肝细胞癌RFA术后疗效重要的影像学手段。正确认识肝细胞癌RFA术后不同疗效的影像学表现,对于及时、准确地发现术后肿瘤残余、局部肿瘤进展及新发肿瘤尤为重要。针对CT、MRI及功能MRI在肝细胞癌RFA术后疗效评价方面的应用研究进展予以综述。     

Single-photon emission computed tomography/computed tomography in brain tumors

Anatomic imaging procedures (computed tomography [CT] and magnetic resonance imaging [MRI]) have become essential tools for brain tumor assessment. Functional images (positron emission tomography [PET] and single-photon emission computed tomography [SPECT]) can provide additional information useful during the diagnostic workup to determine the degree of malignancy and as a substitute or guide for biopsy. After surgery and/or radiotherapy, nuclear medicine examinations are essential to assess persistence of tumor, to differentiate recurrence from radiation necrosis and gliosis, and to monitor the disease. The combination of functional images with anatomic ones is of the utmost importance for a full evaluation of these patients, which can be obtained by means of imaging fusion. Despite the fast-growing diffusion of PET, in most cases of brain tumors, SPECT studies are adequate and provide results that parallel those obtained with PET. The main limitation of SPECT imaging with brain tumor-seeking radiopharmaceuticals is the lack of precise anatomic details; this drawback is overcome by the fusion with morphological studies that provide an anatomic map to scintigraphic data. In the past, software-based fusion of independently performed SPECT and CT or MRI demonstrated usefulness for brain tumor assessment, but this process is often time consuming and not practical for everyday nuclear medicine studies. The recent development of dual-modality integrated imaging systems, which allow the acquisition of SPECT and CT images in the same scanning session, and their co-registration by means of the hardware, has facilitated this process. In SPECT studies of brain tumors with various radiopharmaceuticals, fused images are helpful in providing the precise localization of neoplastic lesions, and in excluding the disease in sites of physiologic tracer uptake. This information is useful for optimizing diagnosis, therapy monitoring, and radiotherapy treatment planning, with a positive impact on patient management.     

Scintigraphic techniques for the diagnosis of infectious disease of the musculoskeletal system

In imaging infectious diseases of the musculoskeletal system, the metabolic information provided by nuclear medicine studies complements the structural information of radiologic modalities. Often the diagnosis can be confirmed by combining the methods in a diagnostic algorithm. The decision about whether a single study is best depends on the clinical setting and the questions that require an answer. Whereas radiography, magnetic resonance imaging (MRI), and computed tomography (CT) usually focus on a single area, nuclear medicine imaging offers the advantage of whole body imaging. However, despite significant improvements it cannot approach the detailed anatomical visualization provided by MRI or CT. In most cases scintigraphy is a very sensitive (e.g., bone scan, positron emission tomography) and often quite specific tool (e.g., white blood cell scintigraphy). The metabolic information of the single scintigraphic procedure depends on the accumulation mechanism. For the work-up of infectious disorders different radiopharmaceuticals can be used, and the decision for the best modality should be tailored to the clinical question and the special pathophysiologic condition of the infection. This article describes the most common nuclear medicine studies and their clinical relevance in some infectious diseases.