[Soft tissue sarcoma: how can posttreatment alterations be distinguished from recurrences?] / Weichteilsarkome: Wie lassen sich posttherapeutische Veränderungen von Rezidiven unterscheiden?

The recognition of recurrent soft tissue sarcomas and the differentiation from post-treatment alterations is complex. This article aims to assist the clinical radiologist in the systematic evaluation of local follow-up imaging in soft tissue sarcoma patients. Soft tissue sarcomas encompass multiple entities with different recurrence rates and follow-up intervals. Approved and up to date recommendations are provided, including imaging techniques. The past medical history of the patient, the clinical situation and previous therapies should be known in detail, including surgery, radiation therapy and chemotherapy. Previous imaging results should be consulted, if available. This article describes the time-dependent imaging spectrum of local post-therapeutic as well as local treatment-related complications. These include early complications, such as seromas, hematomas and infections, as well as late complications, including edema, fibrosis and joint stiffness, and also inflammatory pseudotumors, which may occur after variable time intervals. The imaging appearance of local recurrent and radiation-associated sarcoma are elucidated. In particular, magnetic resonance imaging (MRI) criteria are provided, which may help in differentiating post-therapeutic alterations from recurrent soft tissue sarcomas.

Parallel imaging of the cervical spine at 3T: optimized trade-off between speed and image quality.

BACKGROUND AND PURPOSE: Patients with cervical spine syndrome often experience pain during the MR examination. Our aim was to compare the quality of cervical spine MR images obtained by parallel imaging with those of nonaccelerated images, with the goal of shortening the examination time while preserving adequate image quality. MATERIALS AND METHODS: A phantom study and examinations of 10 volunteers and 26 patients were conducted on a clinical 3T scanner. Acquisitions included axial T2WI, sagittal T2WI, T1WI, and T2TIRM sequences. Nonaccelerated sequences and accelerated sequences with different numbers of averages and different accelerations, with a scanning time reduction of 67%, were performed. For quantitative analysis, the SNR was obtained from the phantom measurements, and the NU was calculated from the volunteer measurements. For qualitative analysis, 3 independent readers assessed the delineation of anatomic structures in volunteers and the visibility of degenerative disease in patients. RESULTS: In the phantom study, as expected, the SNR of the nonaccelerated images was higher than the SNR of the same sequence with parallel imaging. In vivo, the NU was higher when applying fewer averages or parallel imaging, compared with the nonaccelerated images. The analysis of the subjective parameters in the volunteers and patients showed that a scanning time of 48% of the original protocol could be obtained by combining the following sequences: sagittal T1WI with 1 average; sagittal T2WI with acceleration factor 3; sagittal T2TIRM with acceleration factor 2; and axial T2* GRE with acceleration factor 2. CONCLUSIONS: Parallel imaging of the cervical spine at 3T allows shortening of the examination time by 52%, preserving adequate image quality.

Assessment of articular cartilage repair tissue after matrix-associated autologous chondrocyte transplantation or the microfracture technique in the ankle joint using diffusion-weighted imaging at 3 Tesla.

OBJECTIVE: The objective was to compare patients after matrix-associated autologous chondrocyte transplantation (MACT) and microfracture therapy (MFX) of the talus using diffusion-weighted imaging (DWI), with morphological and clinical scoring. MATERIALS AND METHODS: Twenty patients treated with MACT or MFX (10 per group) were examined using 3 T magnetic resonance imaging (MRI) at 48 ± 21.5 and 59.6 ± 23 months after surgery, respectively. For comparability, patients from each group were matched by age, body mass index, and follow-up. American Orthopaedic Foot and Ankle Society (AOFAS) score served as clinical assessment tool pre- and postoperatively. DWI was obtained using a partially balanced, steady-state gradient echo pulse sequence, as well as the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score, based on a 2D proton density-weighted turbo spin-echo sequence and a 3D isotropic true fast imaging with steady-state precession sequence. Semi-quantitative diffusion quotients were calculated after region of interest analysis of repair tissue (RT) and healthy control cartilage, and compared among both groups. RESULTS: The mean AOFAS score improved significantly (P = 0.001) for both groups (MACT: 48.8 ± 20.4-83.6 ± 9.7; MFX: 44.3 ± 16.5-77.6 ± 13.2). No differences in the AOFAS (P = 0.327) and MOCART (P = 0.720) score were observed between MACT and MFX postoperatively. DWI distinguished between healthy cartilage and cartilage RT in the MFX group (P = 0.016), but not after MACT treatment (P = 0.105). Significant correlations were found between MOCART score and DWI index after MFX (Pearson: -0.648; P = 0.043), and between the diffusivity and longer follow-up interval in MACT group (Pearson: -0.647, P = 0.043). CONCLUSION: Whereas conventional scores reveal a similar outcome after MACT or MFX treatment in the ankle joint, DWI was able to distinguish between different RT qualities, as reported histologically for these diverse surgical procedures.

[Pathological changes of the hypopharynx in the focus of imaging]. / Pathologische Veränderungen des Hypopharynx im Brennpunkt der Bildgebung.

The spectrum of pathological changes in anatomical sections of the hypopharynx ranges from benign pathologies to hypopharyngeal carcinoma. Beside the clinical status and the endoscopic evaluation performed by ear, nose and throat specialists, imaging techniques play an important role in pre-therapeutic and post-therapeutic diagnostics and in the follow-up of pharyngeal disease patterns, especially for malignant lesions. A conventional x-ray swallow examination, contrast-enhanced multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI), as well as positron emission tomography (PET) and positron emission tomography computed tomography (PET-CT) are applied depending on the medical question and disease. Especially in radiological oncology, it is extremely important in regions which are clinically difficult to assess to determine the exact localization and extent of hypopharyngeal pathologies to plan the optimal therapy for the patient. This article demonstrates the radiological appearance of pathological changes of the hypopharynx and discusses in particular the hypopharynx carcinoma in the focus of pre-therapeutic and post-therapeutic imaging.

[Radiological normal anatomy of the larynx and pharynx and imaging techniques]. / Radiologische Normalanatomie des Larynx und Pharynx sowie bildgebende Techniken.

The larynx and the pharynx represent anatomically as well as functionally a very complex organ which serves as an airway and a nutrition channel. Knowledge of anatomy and anatomical topography is therefore a fundamental basis for the evaluation of any pathological process. Beside the clinical examination and endoscopy performed by ear, nose and throat specialists, imaging techniques play a crucial role in pre-therapeutic and post-therapeutic diagnostics. The radiologist employs a conventional x-ray swallow examination, as well as contrast-enhanced multidetector computed tomography (MDCT), magnetic resonance imaging (MRI), positron emission tomography (PET) and positron emission tomography-computed tomography (PET-CT), depending on the medical problem in question. The following article demonstrates the functional and especially the structural anatomy of the larynx and the pharynx. Furthermore, the broad range of imaging techniques in clinical use is discussed.

High-field, high-resolution, susceptibility-weighted magnetic resonance imaging: improved image quality by addition of contrast agent and higher field strength in patients with brain tumors.

INTRODUCTION: To demonstrate intratumoral susceptibility effects in malignant brain tumors and to assess visualization of susceptibility effects before and after administration of the paramagnetic contrast agent MultiHance (gadobenate dimeglumine; Bracco Imaging), an agent known to have high relaxivity, with respect to susceptibility effects, image quality, and reduction of scan time. METHODS: Included in the study were 19 patients with malignant brain tumors who underwent high-resolution, susceptibility-weighted (SW) MR imaging at 3 T before and after administration of contrast agent. In all patients, Multihance was administered intravenously as a bolus (0.1 mmol/kg body weight). MR images were individually evaluated by two radiologists with previous experience in the evaluation of pre- and postcontrast 3-T SW MR images with respect to susceptibility effects, image quality, and reduction of scan time. RESULTS: In the 19 patients 21 tumors were diagnosed, of which 18 demonstrated intralesional susceptibility effects both in pre- and postcontrast SW images, and 19 demonstrated contrast enhancement in both SW images and T1-weighted spin-echo MR images. Conspicuity of susceptibility effects and image quality were improved in postcontrast images compared with precontrast images and the scan time was also reduced due to decreased TE values from 9 min (precontrast) to 7 min (postcontrast). CONCLUSION: The intravenous administration of MultiHance, an agent with high relaxivity, allowed a reduction of scan time from 9 min to 7 min while preserving excellent susceptibility effects and image quality in SW images obtained at 3 T. Contrast enhancement and intralesional susceptibility effects can be assessed in one sequence.

High-resolution contrast-enhanced, susceptibility-weighted MR imaging at 3T in patients with brain tumors: correlation with positron-emission tomography and histopathologic findings.

BACKGROUND AND PURPOSE: The purpose of this work was to demonstrate susceptibility effects (SusE) in various types of brain tumors with 3T high-resolution (HR)-contrast-enhanced (CE)-susceptibility-weighted (SW)-MR imaging and to correlate SusE with positron-emission tomography (PET) and histopathology. MATERIALS AND METHODS: Eighteen patients with brain tumors, scheduled for biopsy or tumor extirpation, underwent high-field (3T) MR imaging. In all of the patients, an axial T1-spin-echo (SE) sequence and an HR-SW imaging sequence before and after IV application of a standard dose of contrast agent (MultiHance) was obtained. Seven patients preoperatively underwent PET. The frequency and formation of intralesional SusE in all of the images were evaluated and correlated with tumor grade as determined by PET and histopathology. Direct correlation of SusE and histopathologic specimens was performed in 6 patients. Contrast enhancement of the lesions was assessed in both sequences. RESULTS: High-grade lesions demonstrated either high or medium frequency of SusE in 90% of the patients. Low-grade lesions demonstrated low frequency of SusE or no SusE. Correlation between intralesional frequency of SusE and histopathologic, as well as PET, tumor grading was statistically significant. Contrast enhancement was equally visible in both SW and SE sequences. Side-to-side comparison of tumor areas with high frequency of SusE and histopathology revealed that intralesional SusE reflected conglomerates of increased tumor microvascularity. CONCLUSIONS: 3T HR-CE-SW-MR imaging shows both intratumoral SusE not visible with standard MR imaging and contrast enhancement visible with standard MR imaging. Because frequency of intratumoral SusE correlates with tumor grade as determined by PET and histopathology, this novel technique is a promising tool for noninvasive differentiation of low-grade from high-grade brain tumors and for determination of an optimal area of biopsy for accurate tumor grading.