Primary nasopharyngeal non-Hodgkin’s lymphoma: imaging patterns on MR imaging

ObjectivesTo summarize the distinct imaging features of different subtypes of primary nasopharyngeal non-Hodgkin's lymphomas (NHLs).Materials and methodsClinical data and magnetic resonance imaging findings of 71 patients with histologically proven primary nasopharyngeal NHLs were retrospectively reviewed. The tumor distribution, signal intensity, lesion texture, contrast enhancement properties, extra-chamber involvement, regional structure invasion, and cervical lymphadenopathy were evaluated and compared between different subtypes of NHLs.ResultsOf the patients, 70.4% had B-cell lymphomas; 64.8% had symmetrical and diffuse involvement of nasopharynx walls; and 19.7% had superficial ulcerations. Extra-chamber involvement and regional structure invasion occurred in most patients. The frequency of neck node involvement was up to 83.10%; 62.7% of them were bilateral involvement. Patients with T-cell or nature killer/T-cell NHLs had a higher incidence of superficial ulcerations, nasal cavity, and paranasal sinus invasion than B-cell NHLs (P< .05). Patients with B-cell NHLs had a higher incidence of cervical lymphadenopathy specifically in Level VA and parotid region than T-cell or nature killer/T-cell (NK/T-cell) NHLs (P< .05).ConclusionPrimary nasopharyngeal NHLs had some characteristic imaging features and different subtypes of nasopharyngeal NHLs had some distinct imaging features.     

Non-FDG imaging of atherosclerosis: Will imaging of MMPs assess plaque vulnerability?

Acute ruptures of atherosclerotic plaques with subsequent occlusion account for the vast majority of clinical events such as myocardial infarction or stroke. New imaging approaches focusing on the visualization of inflammation in the vessel wall could emerge as tools for individualized risk assessment and prevention of events. To this end, PET employing ¹⁸F-fluorodeoxyglucose (FDG) has recently been introduced for the first clinical trials. Although this approach nicely visualizes plaques inflammation questions remain with respect to if and how this inflammatory signal can be employed for predicting individual plaque rupture. Molecular imaging of proteases such as matrix-metalloproteinases (MMPs) involved in several steps in plaque progression driving plaques into vulnerable, rupture-prone states seems a promising alternative approach. This review introduces and discusses the vulnerable plaque concept, animal models with human-like plaque ruptures and the potential of a FDG versus a non-FDG MMP-targeted strategy to image rupture-prone plaques.     

Is postcontrast trueFISP imaging advantageous?

RATIONALE AND OBJECTIVES: Contrast of trueFISP images depends mainly on the T2/T1 ratio. Consequently, there is a potential gain in signal intensity after administration of paramagnetic contrast medium despite the strong T2 weighting. The purpose of this study was to analyze signal intensities of abdominal organs after applying contrast medium and to determine whether this yields an improved contrast for pathologies compared with precontrast trueFISP. MATERIALS AND METHODS: Fifty patients underwent an abdominal examination, including the trueFISP sequence before and after the administration of contrast medium. All images were obtained with a 1.5 T system. The mean signal-to-noise ratio before and after contrast medium was assessed for abdominal organs, vessels, muscle, and fat. The contrast-to-noise ratio (CNR) of pathologic lesions was calculated. RESULTS: The trueFISP sequence yielded a higher signal-to-noise ratio after application of contrast medium for all organs except for fat and the aorta. CNR of solid lesions (angiomyolipoma, liver adenoma, liver hemangioma, hepatocellular carcinoma) increased whereas contrast of cysts decreased. CONCLUSIONS: TrueFISP imaging after application of contrast medium led to better CNR for many solid lesions while cysts showed a diminished contrast. We advise trueFISP imaging sequences before and after contrast medium application.     

Positron emission tomography/magnetic resonance imaging: the next generation of multimodality imaging?

Multimodal imaging is now well-established in routine clinical practice. Especially in the field of nuclear medicine, new positron emission tomography (PET) installations comprise almost exclusively combined PET/computed tomography (CT) scanners rather than PET-only systems. However, PET/CT has certain notable shortcomings, including the inability to perform simultaneous data acquisition and the significant radiation dose to the patient contributed by CT. Magnetic resonance imaging (MRI) offers, compared with CT, better contrast among soft tissues as well as functional-imaging capabilities. Therefore, the combination of PET with MRI provides many advantages that go far beyond simply combining functional PET information with structural MRI information. Many technical challenges, including possible interference between these modalities, have to be solved when combining PET and MRI, and various approaches have been adapted to resolving these issues. Here, we present an overview of current working prototypes of combined PET/MRI scanners from different groups. In addition, besides PET/MRI images of mice, the first such images of a rat acquired with the first commercial clinical PET/MRI scanner, are presented. The combination of PET and MRI is a promising tool in preclinical research and will certainly progress to clinical application.     

靶影象(target imaging)

CT在中枢神经系统应用中,一般层厚为5～10毫米,大的象素使空间分辨力不比目前应用的X线图象好。同时CT 分度范围为-1000～ 1000,高密度物质分辨力差,在骨骼系统诊断中有困难。为此减小象素以提高空间分辨力,考虑延长CT 值分度范围,以提高密度分辨力。在新的改良软件中加入高分解能力的演算方法,由于变调传导相关系数的改良使空间分辨力大幅度提高。     

The spectrum of imaging appearances of müllerian duct anomalies: focus on MR imaging

Müllerian duct anomalies (MDAs) are the result of incomplete development, vertical or lateral fusion, or absorption of the müllerian ducts. The range of anomalies includes uterovaginal agenesis or hypoplasia, unicornuate uterus, uterus didelphys, bicornuate uterus, septate uterus, and arcuate uterus. Correct diagnosis and classification of these anomalies are essential because pregnancy outcomes and treatment options vary between the types of anomaly. Furthermore, early identification of MDAs helps to avoid prolonged symptomatic periods and the complications that may subsequently arise, such as infertility, endometriosis, and neoplasm. Although many of these abnormalities are initially diagnosed by ultrasound or hysterosalpingography, MR imaging is the most accurate noninvasive modality available for classification of the various anomalies because of its better anatomic assessment compared with other diagnostic modalities. Familiarity with the wide variety of MDA presentations can help in the planning of appropriate treatment.     

MR motility imaging in Crohn’s disease improves lesion detection compared with standard MR imaging

Objective

To evaluate retrospectively in patients with Crohn’s disease (CD) if magnetic resonance (MR) motility alterations correlate with CD typical lesions leading to an increased detection rate.

Methods

Forty patients with histologically proven CD underwent MR enterography (MRE), including coronal cine sequences (cine MRE), in addition to the standard CD MR protocol. Two blinded readings were performed with and without cine MRE. Locations presenting motility alterations on the cine sequences were analysed on standard MRE for CD-related lesions. This was compared with a second reading using the standard clinical MRE protocol alone.

Results

The number of lesions localised by cine MRE and identified on standard MRE compared with standard MRE alone were 35/24 for wall thickening (p?=?0.002), 24/20 for stenoses (p?=?0.05), 17/11 for wall layering (p?=?0.02), 5/3 for mucosal ulcers (p?=?0.02) and 21/17 for the comb sign (p?=?0.05). Overall, cine MRE detected 35 more CD-specific findings than standard MRE alone (124/89; p?=?0.007) and significantly more patients with CD-relevant MR findings (34/28; p?=?0.03).

Conclusion

CD lesions seem to be associated with motility changes and this leads to an increased lesion detection rate compared with standard-MRE imaging alone.     

Does radiologist recommendation for follow-up with the same imaging modality contribute substantially to high-cost imaging volume?

PURPOSE: To retrospectively measure repeat rates for high-cost imaging studies, determining their causes and trends, and the impact of radiologist recommendations for a repeat examination on imaging volume. MATERIALS AND METHODS: This HIPAA-compliant study had institutional review board approval, with waiver of informed consent. Repeat examination was defined as a same-modality examination performed in the same patient within 0 days to 7 months of a first examination. From a database of all radiology examinations (>2.9 million) at one institution from May 1996 to June 2003, a computerized search identified head, spine, chest, and abdominal computed tomographic (CT), brain and spine magnetic resonance (MR) imaging, pelvic ultrasonography (US), and nuclear cardiology examinations with a prior examination of the same type within 7 months. Examination pairs were subdivided into studies repeated at less than 2 weeks, between 2 weeks and 2 months, or between 2 and 7 months. Automated classification of radiology reports revealed whether a repeat examination from June 2002 to June 2003 had been preceded by a radiologist recommendation on the prior report. Trends over time were analyzed with linear regression, and 95% confidence intervals were calculated. RESULTS: Between July 2002 and June 2003, 31 111 of 100 335 examinations (31%) were repeat examinations. Body CT (9057 of 20 177 [45%] chest and 8319 of 22 438 [37%] abdomen) and brain imaging (6823 of 18 378 [37%] CT and 3427 of 11 455 [30%] MR imaging) represented the highest repeat categories. Among five high-cost, high-volume imaging examinations, 6426 of 85 014 (8%) followed a report with a radiologist recommendation. Most common indications for examination repetition were neurologic surveillance within 2 weeks and cancer follow-up at 2-7 months. From 1997 to mid-2003, MR imaging and CT repeat rates increased (0.71% per year [P < .01] and 1.87% per year [P < .01], respectively). CONCLUSION: Repeat examinations account for nearly one-third of high-cost radiology examinations and represent an increasing proportion of such examinations. Most repeat examinations are initiated clinically without a recommendation by a radiologist.     

Pelvic imaging: multicystic uterine cervical lesions. Can magnetic resonance imaging differentiate benignancy from malignancy?

PURPOSE: To evaluate whether magnetic resonance imaging (MRI) can be used to differentiate between malignant and benign multicystic uterine cervical lesions. MATERIAL AND METHODS: Twenty-two patients with cervical adenocarcinomas, including minimal deviation adenocarcinoma, and five patients with benign multicystic lesions were classified as a percentage of solid components on MRI. Cystic components were further classified by average cyst diameter and signal intensity of the cyst fluid on T1WI. RESULTS: All nine of the entirely solid lesions were malignant. In contrast, two of the entirely cystic lesions were benign. Ten of the ordinary adenocarcinomas had both solid and cystic components. However, three of the 16 solid and cystic lesions were benign. Lesions composed of cysts smaller than 5mm tended to be malignant; however, some lesions composed of larger cysts were also malignant. Three of 5 lesions with low-signal and 7 of 10 with intermediate-signal fluid were malignant. CONCLUSION: The malignancy potential was higher in the lesions with a higher percentage of solid components. However, determining whether multicystic lesions were benign or malignant based on the existence of solid components, the average cyst size, and the signal intensity of cyst fluid was impossible. Although a multicystic lesion with solid components in the deep cervical stroma had been reported as a MR finding of a minimal deviation adenocarcinoma, this does not appear to be pathognomonic.     

What do we expect from imaging?

The objectives of imaging in gynecologic cancer include tumor detection, tumor diagnosis, staging, and follow-up. In addition, both monitoring response to treatment and differentiating tumor recurrence from post-treatment changes are important indications for imaging. In 2001 it was estimated that there would be 38,300 cases of endometrial cancer, 23,400 cases of ovarian cancer, and 12,900 cases of cervical cancer. This article reviews what information is required by the practicing gynecologist or gynecologic oncologist prior to surgery and briefly summarizes state-of-the-art imaging in answering clinically pertinent questions.