Multiexponential T2 relaxometry of benign and malignant adipocytic tumours.

BACKGROUND: We investigated a recently proposed multiexponential (Mexp) fitting method applied to T2 relaxometry magnetic resonance imaging (MRI) data of benign and malignant adipocytic tumours and healthy subcutaneous fat. We studied the T2 distributions of the different tissue types and calculated statistical metrics to differentiate benign and malignant tumours. METHODS: Twenty-four patients with primary benign and malignant adipocytic tumours prospectively underwent 1.5-T MRI with a single-slice T2 relaxometry (Carr-Purcell-Meiboom-Gill sequence, 25 echoes) prior to surgical excision and histopathological assessment. The proposed method adaptively chooses a monoexponential or biexponential model on a voxel basis based on the adjusted R2 goodness of fit criterion. Linear regression was applied on the statistical metrics derived from the T2 distributions for the classification. RESULTS: Healthy subcutaneous fat and benign lipoma were better described by biexponential fitting with a monoexponential and biexponential prevalence of 0.0/100% and 0.2/99.8% respectively. Well-differentiated liposarcomas exhibit 17.6% monoexponential and 82.4% biexponential behaviour, while more aggressive liposarcomas show larger degree of monoexponential behaviour. The monoexponential/biexponential prevalence was 47.6/52.4% for myxoid tumours, 52.8/47.2% for poorly differentiated parts of dedifferentiated liposarcomas, and 24.9/75.1% pleomorphic liposarcomas. The percentage monoexponential or biexponential model prevalence per patient was the best classifier distinguishing between malignant and benign adipocytic tumours with a 0.81 sensitivity and a 1.00 specificity. CONCLUSIONS: Healthy adipose tissue and benign lipomas showed a pure biexponential behaviour with similar T2 distributions, while decreased adipocytic cell differentiation characterising aggressive neoplasms was associated with an increased rate of monoexponential decay curves, opening a perspective adipocytic tumour classification.

Fatty masses of the abdomen and pelvis and their complications.

There are numerous common and rare macroscopic fat-containing masses found in the abdomen and pelvis. These include benign masses, such as lipoleiomyoma, ovarian teratoma, mesenteric teratoma, and lipoma, as well as malignant masses, including liposarcoma and malignant transformation of benign entities. Any mass may become symptomatic due to the development of a complication which may range from ovarian torsion to intussusception to hemorrhage. Imaging plays a vital role in diagnosis and treatment planning when confronted with a symptomatic fat-containing mass.

Tumor de grasa parda: Hibernoma / Brown fat tumor: Hibernoma

Se presenta el caso de un paciente de 45 años para realización de RMN de hombro por tumoración. La RMN permite detectar un hibernoma, tumor benigno derivado del tejido adiposo pardo. Se describen los hallazgos derivados de la RMN, el tratamiento empleado por el médico tratante y los métodos de imágenes aplicables

The case of a 45-year-old patient for performing NMR of the shoulder by tumor is described here. NMR allows the detection of a hibernoma, a benign tumor derived from brown adipose tissue. The findings derived from NMR, the treatment used by the attending physician and the applicable imaging methods are described

Differentiating solid, non-macroscopic fat containing, enhancing renal masses using fast Fourier transform analysis of multiphase CT.

OBJECTIVE: To test the feasibility of two-dimensional fast Fourier transforms (FFT)-based imaging metrics in differentiating solid, non-macroscopic fat containing, enhancing renal masses using contrast-enhanced CT images. We quantify image-based intratumoral textural variations (indicator of tumor heterogeneity) using frequency-based (FFT) imaging metrics. METHODS: In this Institutional Review Board approved, Health Insurance Portability and Accountability Act -compliant, retrospective case-control study, we evaluated 156 patients with predominantly solid, non-macroscopic fat containing, enhancing renal masses identified between June 2009 and June 2016. 110 cases (70%) were malignant RCC, including clear cell, papillary and chromophobe subtypes and, 46 cases (30%) were benign renal masses: oncocytoma and lipid-poor angiomyolipoma. Whole lesions were manually segmented using Synapse 3D (Fujifilm, CT) and co-registered from the multiphase CT acquisitions for each tumor. Pathological diagnosis of all tumors was obtained following surgical resection. Matlab function, FFT2 was used to perform the image to frequency transformation. RESULTS: A Wilcoxon rank sum test showed that FFT-based metrics were significantly (p < 0.005) different between 1. benign vs malignant renal masses, 2. oncocytoma vs clear cell renal cell carcinoma and 3. oncocytoma vs lipid-poor angiomyolipoma. Receiver operator characteristics analysis revealed reasonable discrimination (area under the curve >0.7, p < 0.05) within these three groups of comparisons. CONCLUSION: In combination with other metrics, FFT-metrics may improve patient management and potentially help differentiate other renal tumors. Advances in knowledge: We report for the first time that FFT-based metrics can differentiate between some solid, non-macroscopic fat containing, enhancing renal masses using their contrast-enhanced CT data.

Quantification of fat content in lipid-rich myxoid liposarcomas with MRI: a single-center experience with survival analysis.

OBJECTIVE: To determine the fat content of myxoid liposarcomas (MLS) on MRI and to identify any association between lipid content and survival. MATERIALS AND METHODS: The fat percentage of MLS diagnosed between January 2006 and December 2016 at a single institution was assessed by two radiologists on preoperative MR images. A Cox proportional hazard model was used to determine any association between tumor fat percentage and survival time. Tumor fat percentage was the single predictor in the model. A significance level of 0.05 was used. The Kaplan-Meier estimator was also used to provide a nonparametric estimate of the survivor function within the entire sample and within two patient subgroups consists of lipid-rich and lipid-poor tumors. Lipid-rich tumors were defined as any tumors showing more than 20% of fat on MRI. A 20% cutoff was determined arbitrarily. RESULTS: Of the 43 cases identified through retrospective review, 8 tumors demonstrated ≥10% fat on MRI, and 4 tumors demonstrated ≥20% fat (highest fat percentage, 38%). There was no significant survival difference between patients with high tumor fat, which was defined as ≥20% fat, compared with those with little to no tumor fat. CONCLUSION: Myxoid liposarcomas may demonstrate a higher fat content on MRI than has previously been reported in the literature. Increased tumor fat percentage in lipid-rich tumors was not found to be associated with increased risk of death. Radiologists must be aware of the existence of MLS lesions with higher fat content.

Intraoperative optical coherence tomography for soft tissue sarcoma differentiation and margin identification.

BACKGROUND AND OBJECTIVE: Sarcomas are rare but highly aggressive tumors, and local recurrence after surgical excision can occur in up to 50% cases. Therefore, there is a strong clinical need for accurate tissue differentiation and margin assessment to reduce incomplete resection and local recurrence. The purpose of this study was to investigate the use of optical coherence tomography (OCT) and a novel image texture-based processing algorithm to differentiate sarcoma from muscle and adipose tissue. STUDY DESIGN AND METHODS: In this study, tumor margin delineation in 19 feline and canine veterinary patients was achieved with intraoperative OCT to help validate tumor resection. While differentiation of lower-scattering adipose tissue from higher-scattering muscle and tumor tissue was relatively straightforward, it was more challenging to distinguish between dense highly scattering muscle and tumor tissue types based on scattering intensity and microstructural features alone. To improve tissue-type differentiation in a more objective and automated manner, three descriptive statistical metrics, namely the coefficient of variation (CV), standard deviation (STD), and Range, were implemented in a custom algorithm applied to the OCT images. RESULTS: Over 22,800 OCT images were collected intraoperatively from over 38 sites on 19 ex vivo tissue specimens removed during sarcoma surgeries. Following the generation of an initial set of OCT images correlated with standard hematoxylin and eosin-stained histopathology, over 760 images were subsequently used for automated analysis. Using texture-based image processing metrics, OCT images of sarcoma, muscle, and adipose tissue were all found to be statistically different from one another (P ≤ 0.001). CONCLUSION: These results demonstrate the potential of using intraoperative OCT, along with an automated tissue differentiation algorithm, as a guidance tool for soft tissue sarcoma margin delineation in the operating room. Lasers Surg. Med. 49:240-248, 2017. © 2017 Wiley Periodicals, Inc.

A case of Trousseau syndrome associated with a mucosa-associated lymphoid tissue lymphoma disseminated to the mesenteric adipose tissue.

A 66-year-old man with recurrent stroke within a short period of time was referred to our department from the neurology department to rule out any malignancy. An endoscopic examination revealed a white depressed lesion in the body of the stomach, and computed tomography revealed a high-density area in the mesentery around the stomach. A mucosa-associated lymphoid tissue (MALT) lymphoma was detected from both the stomach biopsy and resected mesenteric specimen. Systemic chemotherapy was administered for the MALT lymphoma (Lugano classification stage IV). Cerebral infarction did not occur after the treatment. We concluded that Trousseau syndrome associated with the MALT lymphoma disseminated to the mesenteric adipose tissue. A MALT lymphoma has a small probability of occurring in Trousseau syndrome.

A diagnostic approach to popliteal fossa masses.

There is a myriad of potential mass lesions that occur in the popliteal fossa, which present as palpable masses or are found incidentally on imaging. With a thorough knowledge and understanding of the appearances and locations of these different entities, one can narrow the differential diagnoses in the majority of cases. This will eliminate unnecessary additional investigations and enable a more rapid management. We present a review of frequently encountered and less common entities using an anatomical sieve, with the aim of providing a diagnostic approach to popliteal fossa masses.

Fat-containing soft-tissue masses in children.

The diagnosis of soft-tissue masses in children can be difficult because of the frequently nonspecific clinical and imaging characteristics of these lesions. However key findings on imaging can aid in diagnosis. The identification of macroscopic fat within a soft-tissue mass narrows the differential diagnosis considerably and suggests a high likelihood of a benign etiology in children. Fat can be difficult to detect with sonography because of the variable appearance of fat using this modality. Fat is easier to recognize using MRI, particularly with the aid of fat-suppression techniques. Although a large portion of fat-containing masses in children are adipocytic tumors, a variety of other tumors and mass-like conditions that contain fat should be considered by the radiologist confronted with a fat-containing mass in a child. In this article we review the sonographic and MRI findings in the most relevant fat-containing soft-tissue masses in the pediatric age group, including adipocytic tumors (lipoma, angiolipoma, lipomatosis, lipoblastoma, lipomatosis of nerve, and liposarcoma); fibroblastic/myofibroblastic tumors (fibrous hamartoma of infancy and lipofibromatosis); vascular anomalies (involuting hemangioma, intramuscular capillary hemangioma, phosphate and tensin homologue (PTEN) hamartoma of soft tissue, fibro-adipose vascular anomaly), and other miscellaneous entities, such as fat necrosis and epigastric hernia.

Semi-automatic segmentation of subcutaneous tumours from micro-computed tomography images.

This paper outlines the first attempt to segment the boundary of preclinical subcutaneous tumours, which are frequently used in cancer research, from micro-computed tomography (microCT) image data. MicroCT images provide low tissue contrast, and the tumour-to-muscle interface is hard to determine, however faint features exist which enable the boundary to be located. These are used as the basis of our semi-automatic segmentation algorithm. Local phase feature detection is used to highlight the faint boundary features, and a level set-based active contour is used to generate smooth contours that fit the sparse boundary features. The algorithm is validated against manually drawn contours and micro-positron emission tomography (microPET) images. When compared against manual expert segmentations, it was consistently able to segment at least 70% of the tumour region (n = 39) in both easy and difficult cases, and over a broad range of tumour volumes. When compared against tumour microPET data, it was able to capture over 80% of the functional microPET volume. Based on these results, we demonstrate the feasibility of subcutaneous tumour segmentation from microCT image data without the assistance of exogenous contrast agents. Our approach is a proof-of-concept that can be used as the foundation for further research, and to facilitate this, the code is open-source and available from www.setuvo.com.

The differential imaging features of fat-containing tumors in the peritoneal cavity and retroperitoneum: the radiologic-pathologic correlation.

There are a variety of fat-containing lesions that can arise in the intraperitoneal cavity and retroperitoneal space. Some of these fat-containing lesions, such as liposarcoma and retroperitoneal teratoma, have to be resected, although resection can be deferred for others, such as adrenal adenoma, myelolipoma, angiomyolipoma, ovarian teratoma, and lipoma, until the lesions become large or symptomatic. The third group tumors (i.e., mesenteric panniculitis and pseudolipoma of Glisson's capsule) require medical treatment or no treatment at all. Identifying factors such as whether the fat is macroscopic or microscopic within the lesion, the origin of the lesions, and the presence of combined calcification is important for narrowing the differential diagnosis. The development and wide-spread use of modern imaging modalities make identification of these factors easier so narrowing the differential diagnosis is possible. At the same time, lesions that do not require immediate treatment are being incidentally found at an increasing rate with these same imaging techniques. Thus, the questions about the treatment methods have become increasingly important. Classifying lesions in terms of the necessity of performing surgical treatment can provide important information to clinicians, and this is the one of a radiologist's key responsibilities.

Radiological localizing techniques in adrenal tumors.

The characterisation of adrenal lesions is a common radiological dilemma. Incidental adrenal lesions are commonly detected with computed tomography (CT), and lesion characterisation is critical. The prevalence of incidental adrenal lesions has been reported to be 2.3% at autopsy and 0.5-2% with abdominal CT. Such lesions are likely to be seen with increasing frequency given the expanding use of radiological imaging in clinical practice. Although the majority of adrenal lesions are benign, in patients with an extra-adrenal primary cancer the probability of an adrenal mass being a metastasis is 52%. Unfortunately, there may be significant overlap between the imaging appearances of benign lesions such as lipid-poor adenomas and malignant lesions, particularly metastases and small adrenal carcinomas. This review highlights recent advances in radiological imaging of adrenal lesions and we discuss the relative merits of CT and magnetic resonance imaging to aid the identification of benign and malignant adrenal lesions and their roles, in combination with biochemical and clinical data, in recognizing common pathologies such as adrenal adenoma, phaeochromocytoma, carcinoma and metastases. We also discuss the radiological characteristics of rarer adrenal lesions including lymphoma, neuroblastic tumours (neuroblastoma, ganglioneuroblastoma, and ganglioneuroma), lipomatous tumours (myelolipoma, angiolipoma, teratoma, lipoma and liposarcoma), in addition to hemangioma, hemangiosarcoma and leiomyosarcoma.

Bilateral adrenal metastases and metastatic subcutaneous deposit in the chest wall from osteosarcoma of the mandible: utility of 18F-FDG-PET.

Adrenal gland involvement as well as metastatic subcutaneous nodule from skeletal osteosarcoma are two extremely rare and unusual manifestations in the natural history of the disease. We herein report a 45 yr old female with both these uncommon occurrences, having large bilateral adrenal metastases and a metastatic subcutaneous nodule in fluorine-18 fluorodesoxy glucose- positron emission tomography the chest wall along with pulmonary metastasis arising from osteosarcoma of the mandible. Our (18)F-FDG-PET study provided all information needed about the disease status in a single examination. It is noteworthy that osteosarcoma of the jaws, thought to be relatively less aggressive compared to its counterpart in long bones, can occasionally give rise to widespread metastases, including atypical sites. A systematic review of the existing literature aiming to explore the patients' characteristics and clinical behavior of adrenal metastases from osteosarcoma, including the present case, was carried out. This was nearly always associated with pulmonary metastases with occasional association with brain or skeletal metastases. Peripheral long bones were the overwhelmingly common site of the primary, the present one being the first report of jaw bone being the primary site, giving rise to adrenal metastases. No age predilection was observed with male to female ratio of 3:1 in the small number of reported cases.

False-positive findings on 18F-FDG PET/CT: differentiation of hibernoma and malignant fatty tumor on the basis of fluctuating standardized uptake values.

OBJECTIVE: Hibernoma is a benign tumor of brown fat that has imaging features similar to those of malignant fat-containing soft-tissue tumors. Hibernoma is metabolically active on (18)F-FDG PET/CT, and its presence can lead to false-positive interpretations. We present three cases in which fatty lesions with increased radiotracer uptake identified on FDG PET/CT turned out to be hibernomas. The standardized uptake values of the lesions were similar to those reported in the literature for liposarcoma. However, all three patients had variable standardized uptake values over time. CONCLUSION: Variation in standardized uptake values over time is an imaging characteristic that may be helpful for differentiating hibernoma and malignant fatty tumor.

Hepatocellular carcinoma developing at the puncture site after percutaneous ethanol injection.

Percutaneous ethanol injection (PEI) is an option for hepatocellular carcinoma (HCC) treatment that is most effective for solitary lesions

Oncogenic osteomalacia: localization of underlying peripheral mesenchymal tumors with use of Tc 99m sestamibi scintigraphy.

OBJECTIVE: To highlight a strategy for potential detection of mesenchymal tumors in oncogenic malacia, as illustrated by 3 cases. METHODS: Three case reports are presented in which successful localization of the offending neoplasm was accomplished by using whole-body Tc 99m sestamibi scanning. Alternative localization techniques are also reviewed. RESULTS: Oncogenic osteomalacia occurs infrequently and is caused by neoplasms that secrete phosphatonins, substances that interfere with proximal tubular resorption of phosphorus and can result in phosphaturia, hypophosphatemia, reduced 1,25-dihydroxyvitamin D concentration, and osteomalacia. Removal of the underlying neoplasm results in complete resolution of all biochemical, pathologic, and physical manifestations of this disorder, as shown in our 3 patients. Because the neoplasms are small and can occur in any tissue compartment, they are difficult to localize, a feature that often results in therapeutic failure. CONCLUSION: We conclude that use of whole-body Tc 99m sestamibi scanning may be an appropriate and cost-effective initial strategy for the localization of peripheral phosphatonin-secreting tumors.