Epipericardial fat pad: CT findings

Epicardial and mediastinal fat around the apex of the heart may produce the classic appearance of a cardiac fat pad filling in the anterior cardiophrenic angle on a lateral chest radiograph. A review of 50 computed tomographic (CT) scans of the chest that were normal save for possible cardiomegaly, together with chest radiographs obtained within a 14-day interval, revealed a wide variation in the configuration of this fat pad in 16 patients (32%). Depending on geometric circumstances, the fat pad may produce a well-marginated region of increased density, a region of increased density with poor margination, or an area of reduced density lying anterior to the heart. In an additional four patients (8%), however, a simulation of a cardiac fat pad was produced by cardiomegaly alone or by relative levoposition of the heart. In these four patients, the left side of the heart contacted the chest wall on the left over a larger than normal area and thereby excluded lung from the vicinity, simulating the appearance of a fat pad where none existed.     

Quadriceps fat pad edema: significance on magnetic resonance images of the knee

Objective While clinically reading magnetic resonance (MR) images of the knees we have occasionally noted edema within the suprapatellar fat pad, with mass effect both on the suprapatellar joint recess posteriorly, and on the quadriceps tendon anteriorly. This MR appearance is analogous to Hoffa’s disease described in the infrapatellar fat pad. We sought to evaluate the frequency and pattern of this finding and to provide clinical and histological correlation. Patients The suprapatellar (quadriceps) fat pad was evaluated in 770 consecutive MR examinations (on 1.5 T and 0.3 T) in 736 patients (353 females and 383 males, age range 5–86 years, mean 44.3 years). Design The MR images were retrospectively evaluated by two observers in consensus for the presence of quadriceps fat pad edema with mass effect. In 46 patients who had intravenous administration of gadolinium, the presence of enhancement was also evaluated. Clinical correlation was performed in abnormal cases; in one patient, 1-year follow-up MRI was evaluated and in one patient a percutaneous biopsy as well as 2-year clinical follow-up was performed. Results Thirty-two (4.2%) knees in 29 patients showed quadriceps fat pad edema and mass effect. In five of these patients imaging of the contralateral knee was also performed and four of these showed symmetric edema. Another five cases had gadolinium-enhanced images with prominent enhancement. Most patients had clinical symptoms of meniscal tears (n=16, 55%) or anterior knee pain (n=8, 27.6%). The remainder had nonspecific pain (n=4, 13.8%) or suspected avascular necrosis (n=1, 3.4%). In the case with 1-year follow-up MRI, improvement was seen. Biopsy in another patient revealed vasculitis with obliteration of the small vessels. Resection of the fat pad in this patient led to complete resolution of the symptoms. Conclusion Suprapatellar fat pad edema may be analogous to Hoffa’s disease, is rare, and may be a cause of anterior knee pain. However, this finding is not infrequent and its precise association with symptoms remains unclear. The study was done when all authors worked at Thomas Jefferson Medical College.     

股四头肌脂肪垫和股前脂肪垫形态和信号特征与膝关节骨性关节炎的相关性研究

目的:探讨股四头肌脂肪垫(QFP)和股前脂肪垫(PFP)的形态和信号特征与膝关节放射学骨性关节炎(ROA)结构改变的关系.方法:回顾性分析纳入的60个临床资料齐全的膝关节X线和MRI检查图像资料,于矢状面PDW-SPAIR序列图像上定量测量QFP最大前后径、最大头尾径、最大斜径和最大面积及PFP的最大厚度.半定量评估Q...     

Change in signal intensity on MRI of fat in the head of markedly emaciated patients

The amount of fat in various parts of the body decreases in emaciated patients, but responds differently to disease processes. The order of disappearance of fat in various parts of the head has rarely been studied with MRI. We imaged ten patients with anorexia nervosa and one cachectic patient with a psychiatric disorder with a 1.5 T imager. Signal intensities of bone marrow of the skull, subcutaneous tissue, and orbits were assessed on T1- and T2-weighted images, and correlated with the body mass index (BMI) and haemoglobin concentration (Hb). On T1-weighted images, five patients (BMI 15.6-17.8 kg/m2, mean 16.6 kg/m2; Hb 10.1-14.2 g/dl, mean 13.8 g/dl) showed the normal pattern of fat. One (BMI 13.6 kg/m2, Hb 10.4 g/dl) lost the high signal of bone marrow, but high signal of subcutaneous tissue and the orbits was preserved. High signal from bone marrow and subcutaneous tissue disappeared in three patients (BMI 11.5-13.5 kg/m2, mean 12.5 kg/m2; Hb 7.9-9.7 g/dl, mean 8.7 g/dl), but orbital high signal was preserved. The remaining two patients (BMI 9.3 and 13.5 kg/m2, mean 11.5 kg/m2; Hb 7.6 and 8.9 g/dl, mean 8.3 g/dl) showed complete loss of high signal from fat in the head. The order of disappearance of fat (bone marrow, subcutaneous fat, then orbits) correlated with both BMI and Hb. Atrophy of bone marrow was demonstrated on T2-weighted images in five patients with BMI 13.5 kg/m2 or less, and Hb 9.7 g/dl or less.     

MRI findings in cerebral fat embolism

The purpose of this retrospective study was to demonstrate the MRI features of cerebral manifestations in patients with fat embolism syndromes in comparison with cerebral CT (CCT). Magnetic resonance imaging was performed according to standard protocols revealing multiple small non-confluent hyperintense intracerebral lesions larger than 2 mm on proton-density and T2-weighted images to various extents in three of four patients with clinically suspected cerebral fat embolism. Cerebral CT was negative in all patients. Our findings confirm that MRI can detect cerebral fat embolism with a higher sensitivity than CCT. Thus, MRI should be the first choice for imaging of cerebral fat embolism. Received 28 November 1997; Revision received 9 March 1998; Accepted 30 March 1998     

Intrahepatic periportal high intensity on hepatobiliary phase images of Gd-EOB-DTPA-enhanced MRI: imaging findings and prevalence in various hepatobiliary diseases

Purpose

To reveal the incidence and degree of intrahepatic periportal high intensity (PHI) on hepatobiliary phase images of Gd-EOB-DTPA-enhanced MRI (EOB-MRI) in patients with or without various hepatobiliary diseases.

Materials and methods

Patients with normal liver (N = 256) and those with hepatic disorder (N = 857) who underwent EOB-MRI were the subjects in this study. Incidence of PHI was evaluated among the patients with normal liver and those with hepatic disorder. Degree of PHI was categorized into four grades and compared among the various hepatic diseases. Enhancement ratios (ER) of the PHI area, background liver with PHI, and background liver in control cases without PHI were evaluated.

Results

PHI was observed in 2.7 % of the patients with hepatic disorder. No PHI was observed in the patients with normal liver. The incidence rates of PHI among various hepatobiliary diseases were as follows; liver cirrhosis 3.1 %, chronic hepatitis 1.0 %, primary biliary cirrhosis 12.5 %, idiopathic portal hypertension 33.3 %. The ER of the PHI area and background liver were 3.92 and 2.48 (p = 0.0002). There were no significant differences between the ER of the PHI area and the ER of background liver in the noncirrhotic control without PHI.

Conclusion

In 2.7 % of the patients with a hepatic disorder, the periportal area was saved from decrease of EOB uptake and it showed PHI.     

MRI诊断髌下脂肪垫损伤的价值

目的探讨膝关节髌下脂肪垫(infrapatellar fat pad,IFP)损伤的磁共振成像(MRI)特点及临床应用价值。方法回顾性分析我院经临床综合诊断或临床随访明确诊断为IFP损伤的111例患者,归纳总结其特征性MRI表现并分级。结果111例中,左膝57例,右膝39例,双膝15例。共126个膝关节根据IFP的信号、裂隙及形态改变进行损伤程度分级轻度54个(42.9%),中度43个(34.1%),重度29个(23.0%)。根据IFP损伤程度指导临床给予相应治疗,终止治疗4~8周随访。治疗前后膝关节VAS评分有显著差异(P<0.05)。结论MRI能准确评估IFP损伤部位及严重程度,为临床治疗提供影像学依据并有较好的指导作用。     

髌下脂肪垫的MRI定量检测及其在膝关节骨关节炎中的应用进展

髌下脂肪垫（IPFP）是参与膝关节骨关节炎（KOA）发生、发展的重要关节组织。MRI可以直接观察和量化IPFP的变化,包括其形态学表现、信号强度变化及血流灌注变化等,有助于推测IPFP在KOA发病及进展中的作用。就基于MRI对IPFP的定量检测方法及其在KOA中的研究现状和进展予以综述。     

Whole-body MRI in neurofibromatosis: incidental findings and prevalence of scoliosis

Objective

To demonstrate incidental findings and scoliosis on whole-body MRI (WBMRI) in patients with neurofibromatosis type 1 and 2 (NF1 &; NF2, respectively), and schwannomatosis.

Materials and methods

Institutional review board approval and written informed consent were obtained for this prospective HIPAA-compliant study. A total of 247 subjects (141 with NF1, 55 with NF2, 51 with schwannomatosis; 132 women (53.5%); mean age, 41?years, range, 18–97?years) underwent WBMRI using coronal STIR (TR/TE: 4190/111?ms, TI: 150?ms) and T1-weighted images (TR/TE: 454/10?ms), 10-mm slice thickness, imaging time ~40 min. Images were reviewed for the presence of incidental findings, outside of nerve sheath tumors. The presence of scoliosis was recorded and curve morphology was assessed and quantified.

Results

Incidental findings other than scoliosis were recorded in 104/247 (42%) patients, most often affecting the musculoskeletal system (65/247 patients, 26%). We found 16/247 (6.5%) significant incidental findings likely to affect clinical management, including avascular necrosis of bone in eight patients (five with NF2), eight insufficiency fractures, and four non-neurogenic neoplasms (Hodgkin's lymphoma, liposarcoma, dermoid cyst, large uterine myoma requiring excision). Scoliosis was seen in 50/247 patients (20%), including 8/55 with NF2 (15%) and 11/51 with schwannomatosis (22%).

Conclusions

Incidental findings in the neurofibromatoses frequently involve the skeleton. Given the relatively high incidence of unsuspected osteonecrosis and stress fractures, close attention to the skeleton on WBMRI is advised. In addition, knowledge of common incidental findings can help clinicians prepare patients who undergo WBMRI for potential unexpected findings.     

Pancreatic signal intensity on Tl- weighted fat saturation MR images: Clinical correlation

To determine whether signal intensity (SI) of the pancreas that was less than that of liver on Tl- weighted fat-suppressed (T1FS) magnetic resonance (MR) images could be used to help predict the presence of pancreatic disease, three blinded independent observers graded pancreatic SI relative to liver and/or renal cortex in 89 patients on T1PS images. Results were correlated with patient age and diagnosis. Among the 47 patients with a clinically normal pancreas, pancreatic SI was higher than that of liver in 42 and equal to that of liver in the rest, none of whom had evidence of fatty pancreas. These five patients had a mean age of 71 years, compared with 55 years for patients whose pancreas was more intense than liver (P=.02). Of the 42 patients with a clinically abnormal pancreas, only eight had pancreatic SI higher than that of liver. The positive predictive value for normal pancreas of an SI higher than that of liver was 84% and the positive predictive value for abnormal pancreas of an SI less than or equal to that of liver was 88%, with an overall accuracy of 86%. If normal pancreatic SI is defined as higher than that of liver for patients younger than 60 years and as equal to or higher than that of liver for patients older than 60 years, the positive predictive value of normal SI becomes 76%, the positive predictive value of decreased SI becomes 100%, and the overall accuracy becomes 83%. Pancreatic SI less than that of liver correlates highly with pancreatic disease, especially in younger patients. Mildly decreased pancreatic SI, equal to that of nondiseased liver, is common in older persons without clinically apparent pancreatic disease.     

Postmortem CT and MRI findings of massive fat embolism

International Journal of Legal Medicine - To elucidate postmortem computed tomography (PMCT) and postmortem magnetic resonance (PMMR) imaging findings suggesting massive fat embolism. Consecutive...     

脊髓MRI高信号的影像学研究与临床意义

1985年，Gebarski等首先发现脊髓损伤患者MRI T2加权像中存在高信号，并提出髓内高信号是一种脊髓水肿或髓内出血；Hyman等则首先报告了慢性脊髓受压亦可产生髓内节段性高信号。正常脊髓组织在T1与T2加权像中均呈中等信号，T1信号略高，而许多脊柱疾患T2加权像中出现明显的高信号，尤其在脊髓型颈椎病中，髓内高信号常常同时伴有明显脊髓压迫，     

MRI appearances of the infrapatellar fat pad in occult traumatic patellar dislocation

AIM: A study was undertaken to determine the status of Hoffa's infrapatellar fat pad in instances of acutely dislocated patellae. MATERIALS AND METHODS: The study consisted of MR examinations performed on 18 consecutive patients with acutely dislocated and relocated patellae with a mean interval between injury and MR examination date of 14.8 days (range 1-60 days). An analysis of the attachments and intrinsic signal characteristics of the fat pad was performed for each individual case. RESULTS: Hoffa's fat pad was abnormal in all cases. Shear injury from the inferior pole of the patella was present in 16 cases. Intrasubstance disruption with fluid filled clefts were noted in 12 cases. In 17 cases diffuse oedema of Hoffa's fat pad had occurred. In nine cases the damaged fat pad mimicked a loose body, while in five cases an intra-articular post-traumatic loose body was identified. CONCLUSION: Post-traumatic change in Hoffa's fat pad is a constant secondary MR feature not previously reported, that can be added to the spectrum of indirect findings in cases of occult patellar dislocation. In addition, the MRI distinction between post-traumatic changes in Hoffa's infrapatellar fat pad from loose osteo-chondral bodies can be difficult, requiring further correlative imaging.     

Ultrasound and MRI findings in appendicular and truncal fat necrosis

Objective The objective was to evaluate ultrasound and MRI in clinical appendicular and truncal fat necrosis. Materials and methods Thirty-three patients (14 men, 19 women, median age 55, range 29–95) were retrospectively evaluated. Histologically, three groups were seen: Group 1 (n = 18) consisted of patients with subcutaneous masses with septal and extrinsic oedema; in Group 2 (n = 11) necrosis occurred within lipomatous tumours and little oedema; and in Group 3 (n = 4) there were large complex masses consistent with Morel-Lavallée lesions. Two experienced radiologists reviewed MR (n = 30) and ultrasound (n = 32) images with consensus agreement. MRI was performed on a 1.5T system with T1-weighted, T2-weighted fat-suppressed and T1-weighted fat-suppressed post-intravenous gadolinium sequences obtained in two orthogonal planes. Ultrasound (linear 5- to 13.5-MHz probe) was performed in the longitudinal and short axis. Anatomical position, size, shape (oval, linear, ill-defined), internal architecture (lobules, septi or stranding), intrinsic signal characteristics, presence of surrounding pseudocapsule, extrinsic linear stranding and vascularity (gadolinium enhancement or power Doppler) were recorded. Results Anatomical locations were buttock/thigh (n = 17), leg (n = 6), upper limb (n = 5) and thoracic/abdominal wall (n = 5) with the majority of lesions (30 out of 33) oval/linear in shape. On ultrasound and MRI most lesions showed internal fat lobules, intervening septi and a surrounding pseudocapsule. Conclusion Fat necrosis can usually be identified as containing multiple fat lobules on ultrasound and MRI despite a varying degree of inflammatory change surrounding and within the mass.     

Determinants of signal intensity in MRI of human astrocytomas

MRI studies at 1.5 T of 38 patients with histologically confirmed astrocytomas were reviewed to search for a relationship of signal intensity with grade of malignancy, rediotherapy used for recurrent tumours and calcium deposits in surgical specimens. Signal intensity of tumours compared with normal brain was rated on a scale of 1 to 5 on T1- and T2-weighted images. Surgical specimens of each tumour were graded histopathologically on a scale of I to III and examined for calcium deposits. CT scans were searched for evidence of calcification. The majority of astrocytomas appeared hypointense on T1-weighted and hyperintense on T2-weighted images. Of 18 tumours with increased signal on T1-weighted images, grade II were prevalent, followed by calcified astrocytomas. Among 14 tumours with decreased signal on T2-weighted images the order was similar, but the ratio of high-grade to low-grade tumours did not differ in relation to signal intensity, while on T1-weighted images the ratio was higher in the group with increased signal intensity. A high grade of malignancy and microcalcifications were associated with an increased signal intensity of astrocytomas on T1-weighted sequences without contrast agent. The above factors did not influence significantly the signal intensity on T2-weighted images. Correspondence to: B. Góraj     

Pericruciate fat pad of the knee: anatomy and pericruciate fat pad inflammation: cadaveric and clinical study emphasizing MR imaging

Objective

The pericruciate fat pad is located in the intercondylar fossa, intimate with the cruciate ligaments. With MR imaging, signal abnormality of the pericruciate fat pad has been observed in patients with posterior knee pain. The purpose of this study was to describe the anatomy of the pericruciate fat pad in cadaveric specimens and to document the clinical spectrum of pericruciate fat pad inflammation.

Materials and Methods

Twelve cadaveric knees underwent MR imaging with T1 and T2 multiplanar images. Cadaveric sections were then prepared for macroscopic evaluation, with additional histologic analysis performed in four cases. MR images in seventeen patients (ten males, seven females; average age, 31.5?years; age range, 19–57?years) involved in intensive sporting activity and with posterior knee pain were reviewed.

Results

MR images in cadaveric specimens showed a fat pad that was located above and between the cruciate ligaments, near their attachment sites in the inner portion of the femoral condyles, within the intercondylar fossa. Fatty tissue covered by a thin layer of synovial membrane was confirmed at histology. Seventeen patients with posterior knee pain and without gross cartilage, meniscal, or ligamentous abnormalities all revealed an increased signal in this fat pad in fluid-sensitive fat-suppressed images, mainly in the sagittal and axial planes. In eight cases, enhancement of this fat pad was demonstrated following intravenous gadolinium administration.

Conclusions

The pericruciate fat pad is a structure located in the intercondylar fossa, intimate with both the anterior and posterior cruciate ligaments. Inflammatory changes in this fat pad may be found in patients, especially athletes with posterior knee pain.     

Herniation of the buccal fat pad into the maxillary antrum: CT findings in three cases

We report the first 3 cases in which CT disclosed herniation of the body of the buccal fat pad into the maxillary antrum. Only 20 cases of traumatic herniation of the buccal fat pad have been described in the literature. In all except one instance, the buccal fat pad herniated into the oral cavity. The only previous report of herniation of the buccal fat pad into the maxillary antrum is in an article published before modern cross-sectional imaging, and the diagnosis was not made preoperatively in that case.     

Diagnostic significance of periesophageal fat pad in ultrasonography for sliding hiatal hernias: sonographic fat pad sign

The aim of the present study was to investigate the diagnostic significance of visualization of periesophageal fat pad in ultrasonography or computed tomography for sliding hiatal hernias. Forty-six controls and 21 esophageal hiatal hernia patients were compared in terms of sonographic and tomographic esophageal diameters. We suggest that absence of periesophageal fat pad sign in ultrasonography or computerized tomography is a noteworthy finding that calls for further investigation for the diagnosis of sliding hiatal hernias.