Rahel A. Kubik-Huch

Value of (18F)-FDG positron emission tomography, computed tomography, and magnetic resonance imaging in diagnosing primary and recurrent ovarian carcinoma

Abstract. The aim of this study was to compare prospectively the accuracy of whole-body positron emission tomography (PET), CT and MRI in diagnosing primary and recurrent ovarian cancer. Nineteen patients (age range 23–76 years) were recruited with suspicious ovarian lesions at presentation (n = 8) or follow-up for recurrence (n = 11). All patients were scheduled for laparotomy and histological confirmation. Whole-body PET with FDG, contrast-enhanced spiral CT of the abdomen, including the pelvis, and MRI of the entire abdomen were performed. Each imaging study was evaluated separately. Imaging findings were correlated with histopathological diagnosis. The sensitivity, specificity and accuracy for lesion characterization in patients with suspicious ovarian lesions (n = 7) were, respectively: 100, 67 and 86 % for PET; 100, 67 and 86 % for CT; and 100, 100 and 100 % for MRI. For the diagnosis of recurrent disease (n = 10), PET had a sensitivity of 100 %, specificity of 50 % and accuracy of 90 %. The PET technique was the only technique which correctly identified a single transverse colon metastasis. Results for CT were 40, 50 and 43 %, and for MRI 86, 100 and 89 %, respectively. No statistically significant difference was seen. Neither FDG PET nor CT nor MRI can replace surgery in the detection of microscopic peritoneal disease. No statistically significant difference was observed for the investigated imaging modalities with regard to lesion characterization or detection of recurrent disease; thus, the methods are permissible alternatives. The PET technique, however, has the drawback of less accurate spatial assignment of small lesions compared with CT and MRI.

Acute mesenteric ischemia caused by spontaneous isolated dissection of the superior mesenteric artery: treatment by percutaneous stent placement

Abstract. Spontaneous and isolated dissection of the superior mesenteric artery is a rare and often fatal event which has been successfully treated by surgery in several reported cases. We present a patient with acute mesenteric ischemia due to superior mesenteric artery dissection who was successfully treated by percutaneous endovascular placement of a Wallstent.

The role of dynamic contrast-enhanced and diffusion weighted magnetic resonance imaging in the female pelvis

Functional imaging by means of dynamic multiphase contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion weighted magnetic resonance imaging (DW-MRI) is now part of the standard imaging protocols for evaluation of the female pelvis. DCE-MRI and DW-MRI are important MR imaging techniques which enable the radiologist to move from morphological to functional assessment of diseases of the female pelvis. This is mainly due to the limitations of morphologic imaging, particularly in lesion characterization, accurate lymph node staging, assessment of tumour response and inability to differentiate post-treatment changes from tumour recurrence. DCE-MRI improves the accuracy of T2WI in staging of endometrial cancer. It also helps differentiate tumour recurrence from radiation fibrosis in patients with cervical cancer. DCE-MRI improves characterization of cystic adnexal lesions and detection of small peritoneal implants in patients with ovarian cancer. DW-MRI is valuable in preoperative staging of patients with endometrial and cervical cancer, especially in detection of extra-uterine disease. It does increase readers confidence for detection of recurrent disease in gynaecological malignancies and improves detection of small peritoneal implants in patients with ovarian cancer. In this review article we give an overview of both DCE-MRI and DW-MRI techniques, concentrating on their main clinical application in the female pelvis, and present a practical approach of the added value of these techniques according to the main pathological conditions, highlighting the pearls and pitfalls of each technique.

Fetal magnetic resonance imaging of the brain: technical considerations and normal brain development.

Abstract. Fetal MRI examines non-invasively the unborn fetus. Ultrafast MRI sequences effectively suppress fetal motion. Multiple case reports and studies have shown that fetal MRI is particularly helpful in the evaluation of the central nervous system. The high contrast-to-noise ratio, the high spatial resolution, the multiplanar capabilities, the large field of view and the simultaneous visualisation of fetal and maternal structures have proven to be advantageous. Fetal MRI is particularly helpful in the evaluation of the normal and pathological development of the brain. Despite the fact that no side effects have been reported or are to be expected, the use of MRI during pregnancy is still limited to the second and third trimester of pregnancy. Magnetic resonance imaging contrast media are not to be used as it passes the placenta. Ultrasound remains the primary screening modality for fetal pathology; fetal MRI can serve as an adjunct or second-line imaging modality.

MR Autopsy in Fetuses

Objective: The purpose of this study was to determine whether postmortem magnetic resonance imaging (MR autopsy) could serve as an alternative to necropsy of fetuses. The value of MR autopsy in the validation of the obstetric management and in risk counseling concerning future pregnancies is discussed. Methods: 10 consecutive, malformed fetuses were examined by postmortem MRI within 24 h of delivery. Prenatal ultrasound (US) was performed in all fetuses. Complete necropsy served as gold standard. Results: MR autopsy confirmed every US diagnosis responsible for termination. All MRI findings were confirmed by necropsy. In two fetuses, necropsy gave additional information relevant for risk counseling. Histologic examination corrected the diagnosis in one case. Conclusions: MR autopsy provides valuable information previously only available from necropsy. In parents who refuse perinatal necropsy, the information obtained by MR autopsy can be used to validate obstetric management and to evaluate the risk for future pregnancies. Necropsy however remains the gold standard.

Breast augmentation and reconstructive surgery: MR imaging of implant rupture and malignancy

Abstract. The purpose of this study was to assess the diagnostic accuracy of MRI in detecting prosthesis integrity and malignancy after breast augmentation and reconstruction. Forty-one implants in 25 patients were analyzed by MRI before surgical removal. Imaging results were compared with ex vivo findings. Magnetic resonance imaging of the breast was performed on a 1.5-T system using a dedicated surface breast coil. Axial and sagittal T2-weighted fast spin-echo as well as dynamic contrast-enhanced T1-weighted gradient-recalled-echo sequences were acquired. The linguine sign indicating collapse of the silicone shell or siliconomas indicating free silicone proved implant rupture, whereas early focal contrast enhancement of a lesion was suspicious for malignancy. The sensitivity for detection of implant rupture was 86.7% with a specificity of 88.5%. The positive and negative predictive values were 81.3 and 92.0%, respectively. The linguine sign as a predictor of intracapsular implant rupture had a sensitivity of 80% with a specificity of 96.2%. Magnetic resonance imaging revealed two lesions with suspicious contrast enhancement (one carcinoma, one extra-abdominal fibromatosis). Magnetic resonance imaging is a reliable and reproducible technique for diagnosing both implant rupture and malignant lesions in women after breast augmentation and reconstruction.

A Study on Mastectomy Samples to Evaluate Breast Imaging Quality and Potential Clinical Relevance of Differential Phase Contrast Mammography

ObjectivesDifferential phase contrast and scattering-based x-ray mammography has the potential to provide additional and complementary clinically relevant information compared with absorption-based mammography. The purpose of our study was to provide a first statistical evaluation of the imaging capabilities of the new technique compared with digital absorption mammography. Materials and MethodsWe investigated non-fixed mastectomy samples of 33 patients with invasive breast cancer, using grating-based differential phase contrast mammography (mammoDPC) with a conventional, low-brilliance x-ray tube. We simultaneously recorded absorption, differential phase contrast, and small-angle scattering signals that were combined into novel high-frequency-enhanced images with a dedicated image fusion algorithm. Six international, expert breast radiologists evaluated clinical digital and experimental mammograms in a 2-part blinded, prospective independent reader study. The results were statistically analyzed in terms of image quality and clinical relevance. ResultsThe results of the comparison of mammoDPC with clinical digital mammography revealed the general quality of the images to be significantly superior (P < 0.001); sharpness, lesion delineation, as well as the general visibility of calcifications to be significantly more assessable (P < 0.001); and delineation of anatomic components of the specimens (surface structures) to be significantly sharper (P < 0.001). Spiculations were significantly better identified, and the overall clinically relevant information provided by mammoDPC was judged to be superior (P < 0.001). ConclusionsOur results demonstrate that complementary information provided by phase and scattering enhanced mammograms obtained with the mammoDPC approach deliver images of generally superior quality. This technique has the potential to improve radiological breast diagnostics.

Advances in magnetic resonance imaging of endometrial cancer

Endometrial cancer is the most commonly diagnosed gynaecological malignancy in affluent societies [1]. It occurs most frequently in white women, with peak incidence between ages 55 and 65. Risk factors include unopposed oestrogen intake, use of tamoxifen, nulliparity, obesity, and diabetes. The incidence of endometrial cancer in the United Kingdom has increased by more than 40% between 1993 and 2007. This significant rise is predominantly due to a large increase in incidence in women aged 60–79 [1]. These trends are very similar for most European countries [2]. The increase in prevalence of obesity and decreases in fertility may partly account for the observed rapid increase in incidence and imply that endometrial cancer in postmenopausal women will become a more substantial public health problem in the future. Prognosis depends on a number of factors, including stage, depth of myometrial invasion, lymphovascular invasion, nodal status and histological grade. Depth of myometrial invasion is the single most important morphologic prognostic factor, correlating with tumour grade, lymph node metastases and overall patient survival. Incidence of lymph node metastases increases from 3% with superficial myometrial invasion (stage IA) to 46% with deep myometrial invasion (stage IB) [3]. Preoperative knowledge of these factors is crucial in tailoring the surgical approach. The histological grade can be determined at endometrial sampling, whereas depth of myometrial invasion can only be assessed preoperatively by MRI. Therefore, MRI can assist in preoperative assessment and treatment planning by accurately predicting depth of myometrial invasion, cervical stromal invasion and lymph node involvement. This information allows selection of patients for pelvic or para-aortic lymph node sampling whilst obviating the need for surgery in patients with low risk disease. MRI can also provide additional useful information such as uterine size, tumour volume, ascites and adnexal pathology which in turn may determine whether the surgical approach is transabdominal, transvaginal or laparoscopic. Lymphadenectomy in early (stage I) endometrial cancer remains a controversial issue. Two large prospective multicentre studies investigated whether pelvic lymphadenectomy could improve survival of women with endometrial cancer [4, 5]. Both studies reported no benefit in overall or recurrence free survival in the patients randomized to lymphadenectomy. Conversely, the SEPAL study [6] showed that in patients with intermediate or high risk of endometrial cancer recurrence, combined pelvic and paraaortic lymphadenectomy reduced the risk of death compared with pelvic lymphadenectomy alone. The authors acknowledged that MRI is an important factor for predicting lymph node metastasis, and in combination with tumour grade and histology could be helpful to discriminate patients with very low risk of recurrence. Therefore, E. Sala Addenbrooke’s Hospital, University Department of Radiology, Box 218, Level 5, Hills Road, Cambridge CB2 0QQ, UK e-mail: es220@radiol.cam.ac.uk

Prenatal diagnosis of fetal malformations by ultrafast magnetic resonance imaging

Prenatal ultrasonography is the primary imaging modality in pregnancy as it allows direct real‐time fetal examination. Antenatal magnetic resonance imaging (MRI) has so far been of limited clinical value owing to poor image quality. This was due to the long acquisition times that were needed to achieve a high enough spatial resolution for assessment of the small fetal anatomic structures resulting in severe motion artefacts. This problem has now been overcome by recent technical improvements.

Is there a role for conventional MRI and MR diffusion-weighted imaging for distinction of skull base chordoma and chondrosarcoma?

Background Chordoma and chondrosarcoma are locally invasive skull base tumors with similar clinical symptoms and anatomic imaging features as reported in the literature. Purpose To determine differentiation of chordoma and chondrosarcoma of the skull base with conventional magnetic resonance imaging (cMRI) and diffusion-weighted MR imaging (DWI) in comparison to histopathological diagnosis. Material and Methods This retrospective study comprised 96 (chordoma, n = 64; chondrosarcoma, n = 32) patients with skull base tumors referred to the Paul Scherrer Institute (PSI) for proton therapy. cMRI signal intensities of all tumors were investigated. In addition, median apparent diffusion coefficient (ADC) values were measured in a subgroup of 19 patients (chordoma, n = 11; chondrosarcoma, n = 8). Results The majority 81.2% (26/32) of chondrosarcomas displayed an off-midline growth pattern, 18.8% (6/32) showed clival invasion, 18.8% (6/32) were located more centrally. Only 4.7% (3/64) of chordomas revealed a lateral clival origin. Using cMRI no significant differences in MR signal intensities were observed in contrast to significantly different ADC values (subgroup of 19/96 patients examined by DWI), with the highest mean value of 2017.2 × 10−6 mm2/s (SD, 139.9 mm2/s) for chondrosarcoma and significantly lower value of 1263.5 × 10−6 mm2/s (SD, 100.2 × 10−6 mm2/s) for chordoma (P = 0.001/median test). Conclusion An off-midline growth pattern can differentiate chondrosarcoma from chordoma on cMRI in a majority of patients. Additional DWI is a promising tool for the differentiation of these skull base tumors.