The efficacy of whole-body FDG-PET or PET/CT for autoimmune pancreatitis and associated extrapancreatic autoimmune lesions

Purpose The aim of this study was to evaluate retrospectively the efficacy of whole-body ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) for autoimmune pancreatitis (AIP) and associated extrapancreatic autoimmune lesions. Methods Whole-body FDG-PET or PET/computed tomography (CT) findings were reviewed in six patients with AIP. The initial PET scans were performed 1 h and 2 h after FDG injection in all six patients. Follow-up PET scans were performed during or following steroid therapy in five patients and in one patient who did not have steroid therapy. Results The initial PET scans revealed intense FDG uptake by AIP in all six patients. The maximum standardized uptake value (SUVmax) increased in four patients and was stable in two patients. The intense uptake in the pancreas disappeared during or following steroid therapy in five patients and in one patient who showed spontaneous remission of AIP. Abnormal FDG uptake by extrapancreatic autoimmune diseases was observed in five of the six patients: sclerosing sialadenitis (n = 5), lymphadenopathy (n = 5), retroperitoneal fibrosis (n = 2), interstitial nephritis (n = 2) and sclerosing cholecystitis (n = 1). Abnormal FDG uptake disappeared in the salivary glands (n = 4), lymph nodes (n = 4), retroperitoneum (n = 2), kidneys (n = 1) and gallbladder (n = 1) during or following steroid therapy and remained in the salivary glands and lymph nodes of a spontaneous remission patient. Conclusion These results suggest that whole-body FDG-PET may be useful for detecting AIP and associated extrapancreatic autoimmune lesions and for monitoring their disease activity but that dual time point imaging may not be useful for differentiating malignancy from AIP.     

局限性自身免疫性胰腺炎的CT影像学特征分析

目的探讨局限性自身免疫性胰腺炎(focal autoimmune pancreatitis,f-AIP)的CT影像学表现特点,以期提高其影像学鉴别诊断水平。方法回顾性分析13例经组织学、IgG4检验或类固醇激素治疗证实的局限性自身免疫性胰腺炎患者的CT影像学资料,从胰腺形态表现、病变区密度及强化方式、胆胰管改变和假包膜结构显示等情况进行分析。结果本研究13例局限性自身免疫性胰腺炎患者中,13例均有局部胰腺肿大(胰头部3例,胰体尾部5例,胰尾部5例),与正常胰腺比较,CT平扫提示病变区密度降低(4例)或降低不明显(9例),增强扫描动脉期均见病变区强化程度较正常胰腺减低,门脉期及延迟期均提示病变区逐渐均匀强化,与正常胰腺强化程度相仿。7例显示病变区有假包膜结构,4例胆管扩张,胰管不规则硬化狭窄显示7例。结论局限性自身免疫性胰腺炎CT影像学表现具有一定的特征性,正确掌握这些特征有助于提高诊断准确率,从而避免不必要的手术治疗。     

Imaging findings in idiopathic pelvic fibrosis

Two patients presented with ureteric obstruction, and voiding symptoms and constipation, respectively, and were examined by means of intravenous urography and computed tomography. One patient was additionally examined by means of MR tomography. After CT (performed in both patients) and MRT (performed in one patient) had shown a diffuse, contrast-enhancing, infiltrating process in the small pelvis with infiltration of adjacent organs and vessels, surgical biopsy proved the diagnosis of idopathic pelvic fibrosis. Extension of retroperitoneal fibrosis below the pelvic rim is very rare. Clinical symptoms of pelvic fibrosis are variable and imaging findings may lead to a broad list of differential diagnoses. We present two patients with idiopathic pelvic fibrosis and discuss radiological findings and differential diagnoses of this rare disease. Received: 6 March 2000 Revised: 30 May 2000 Accepted: 5 June 2000     

A Patient with Psoriatic Arthritis Imaged with FDG-PET/CT Demonstrated an Unusual Imaging Pattern with Muscle and Fascia Involvement: A Case Report

We describe the case of a patient with known history of psoriasis that presented with 1 year of unexplained fever, muscle weakness and marked weight loss, suspicious for B symptoms of a malignant origin. [¹⁸F]-Fluorodeoxyglucose positron emission tomography-computed tomography (FDG-PET/CT) scans demonstrated an unusual serpiginous pattern of uptake in the fascia and muscles as well as lymph node activity. Multiple histological samples, including a final PET-probe guided lymph node surgical resection, excluded malignancy and confirmed the diagnosis of reactive inflammatory changes, with a plausible diagnosis of autoimmune lymphoproliferative syndrome with associated lymphadenitis, fasciitis and myositis, possibly mediated by tumor necrosis factor (TNF) inhibitor. To our knowledge, there is no evidence of a previously reported FDG uptake pattern of fascia and muscle involvement in psoriatic arthritis.     

特发性腹膜后纤维化的MRI诊断

目的：探讨特发性腹膜后纤维化（IRPF）的MRI表现。方法：回顾性分析8例经穿刺活检病理证实的IRPF患者的MRI图像资料。所有患者均行腹部MRI常规扫描,其中5例同时行增强扫描,4例行DWI检查,5例行MRU检查。结果：IRPF呈类圆形或不规则形软组织信号,包绕腹膜后大血管及输尿管等腹膜后器官,早期病变呈稍长T1、稍长T2信号,动态增强扫描动脉期示病灶明显强化,DWI上呈稍高信号;中晚期病变T2WI信号逐渐减低,呈等信号或低信号,动态增强扫描动脉期及静脉期无明显强化,延迟期呈轻度不均匀强化,DWI上呈不均匀稍低信号。当病变包绕输尿管时,MRU检查可见一侧或双侧输尿管变细,病变段以上输尿管积水及肾盂积水。结论：MRI多序列检查有助于IRPF的诊断及鉴别诊断,有较大的临床应用价值。     

特发性腹膜后纤维化的MSCT表现

目的:探讨特发性腹膜后纤维化(IRPF)的CT表现特点,提高对该病的早期诊断准确性.方法:回顾性分析经病理证实的24例IRPF患者的病例资料,主要观察分析病变的部位、形态、范围、边界、密度、强化方式及邻近器官组织的受累情况.结果:本组患者的主要CT表现为肾门水平以下腹膜后区不规则形软组织密度影,近似肌肉密度,增强扫描病灶可无强化或明显强化;包绕腹主动脉前方和/或两侧18例,向下累及两侧髂总动脉8例,累及下腔静脉前方4例,累及肾动脉1例,受累血管均无明显移位;累及输尿管致梗阻性肾积水18例,其中8例双侧受累.结论:IRPF的MSCT表现具有一定特征性,可为临床诊治提供可靠依据.     

Emerging role of FDG-PET/CT in assessing atherosclerosis in large arteries

Atherosclerosis is a dynamic inflammatory disorder. The biological composition and inflammatory state of an atherosclerotic plaque, rather than the degree of stenosis or its size are the major determinants of acute clinical events. A noninvasive technique to detect vulnerable atherosclerotic plaque is critically needed. FDG-PET/CT, a combined functional and structural whole-body imaging modality, holds great potential for this purpose. FDG uptake in large arteries has been frequently observed and is associated with cardiovascular risk factors. FDG accumulates in plaque macrophages and uptake is correlated with macrophage density. It is known that vascular FDG uptake and calcification do not overlap significantly and changes of FDG uptake are common, suggesting that FDG uptake may represent a dynamic inflammatory process. It has been reported that vascular FDG uptake can be attenuated by simvastatin in patients, and by the antiinflammatory drug probucol in rabbits. Vascular FDG uptake has been linked to cardiovascular events in some preliminary studies. Data from basic sciences, and animal and clinical studies support the emerging role of FDG-PET/CT in assessing atherosclerosis in large arteries in humans.     

FDG-PET/CT findings of sarcomatous transformation in neurofibromatosis: a case report

We herein report FDG-PET/CT findings of sarcomatous transformation in a patient with neurofibromatosis type 1 (NF-1). About 5% of patients with NF-1 develop sarcomatous transformation of a malignant peripheral nerve sheath tumor which arises from plexiform neurofibromas and is often associated with a poor prognosis. Morphologic imaging techniques such as Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) are the standard methods to define the anatomic extent of the tumor, although tumor heterogeneity prevents reliable differentiation between benign and malignant lesions. The degree of fluoro-deoxyglucose (FDG) uptake correlates with histologic grade in neurogenic tumors in NF-1 patients. Our patient had a huge mass in the left gluteus area with a large nearly circular focus of increased FDG uptake in the tumor. The mass had a photopenic center. The maximum Standard Uptake Value (SUVmax) of this mass was 6.6. There was CT evidence of invasion of the left iliac wing, left acetabulum, and left superior pubic ramus; however there was no increased FDG uptake in these areas on the PET study. We surmised that the high FDG uptake indicated a high grade sarcoma, which was confirmed histologically. There was also a focal region of increased uptake in the L5 vertebral body, correlating with the CT hypodense lesion, with 2.9 SUVmax. FDG-PET/CT can identify sarcomatous change from benign neurogenic tumor with minimal misregistration, and can also detect metastatic disease. This case illustrates the importance of evaluating both metabolic and morphologic abnormalities to be able to formulate a proper treatment plan. This information can be obtained in a single session, using PET/CT.     

Ductal carcinoma in situ: correlation between FDG-PET/CT and histopathology

Purpose  The aim of this study was to determine if any correlation exists between tumor cell density and fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET)/CT) for pure or predominant ductal carcinoma in situ (DCIS). Materials and methods  Subjects in this retrospective review comprised 11 patients who underwent FDG-PET/CT for DCIS. Pathological tumor cell density and FDG-PET/CT images were compared. A tumor background count density ratio of >1.5 was defined as the detectable range for DCIS. Results  Pathological density of disease was high in eight patients, intermediate in one, and low in two. In all eight patients with a detectable intraductal component on PET/CT, the density of disease was classified as high. In three patients undetected by PET/CT, the density of disease was classified as intermediate or low. On statistical analysis, the correlation between the density of disease and tumor background count density ratio (TBCDR) on PET/CT was significant (<0.05), whereas the nuclear grade and Van Nuys grade were not significant. In the eight patients detected by PET/CT, the discrepancy between histopathological mapping and FDG-PET/CT mapping was >20 mm in four patients and represented underestimation in four patients who showed low density of disease in the peripheral area. Conclusions  Tumor cell density of intraductal carcinoma appears strongly correlated to detection by FDG-PET/CT.     

Autoimmune pancreatitis associated with primary sclerosing cholangitis: MR imaging findings

Autoimmune pancreatitis is a relatively rare type of chronic pancreatitis that may be associated with other autoimmune disorders. The imaging features of this entity may be misleading and suggest the presence of a malignant tumour. We present a case in which MR imaging allowed us to diagnose autoimmune pancreatitis associated with primary sclerosing cholangitis, which is another autoimmune-related disease. Typical MR characteristics of autoimmune pancreatitis include focal or diffuse enlargement of the pancreas, the absence of parenchymal atrophy and significant dilation proximal to the site of stenosis, the absence of peripancreatic spread, the clear demarcation of the lesion and the presence of a peripancreatic rim.     

Bone involvement in patients with lymphoma: the role of FDG-PET/CT

Purpose To evaluate the diagnostic impact and clinical significance of FDG-avid bone lesions detected by FDG-PET/CT in patients with lymphoma. Methods The study population comprised 50 consecutive patients (mean age 41.7±15.5 years; 27 female, 23 male; 41 staging, 9 restaging) with Hodgkin’s disease (n=22) or aggressive non-Hodgkin’s lymphoma (n=28) in whom FDG-avid bone lesions were detected by FDG-PET/CT. All patients had either direct biopsy of the FDG-avid bone lesion (n=18), standard bone marrow biopsy at the iliac crest (BMB; n=43) or both procedures (n=11). In 15 patients, additional MRI of the bone lesions was performed. All patients underwent FDG-PET/CT after the end of treatment. All CT images of FDG-PET/CT scans were analysed independently regarding morphological osseous changes and compared with FDG-PET results. Results In the 50 patients, 193 FDG-avid lesions were found by PET/CT. The mean standardised uptake value was 6.26 (±3.22). All direct bone biopsies (n=18) of the FDG-avid lesions proved the presence of lymphomatous infiltration. BMB (n=43) was positive in 12 patients (27.9%). In CT, 32 of 193 (16.6%) lesions were detected without the PET information. No additional morphological bone infiltration was detected on CT compared with FDG-PET. All morphological bone alterations on CT scans persisted after the end of therapy. Additional PET/CT information regarding uni- or multifocal bone involvement resulted in lymphoma upstaging in 21 (42%) patients compared with the combined information provided by CT and BMB. Conclusion In patients with FDG-avid bone lesions, FDG-PET is superior to CT alone or in combination with unilateral BMB in detecting bone marrow involvement, leading to upstaging in a relevant proportion of patients.     

腹膜后纤维化的影像学诊断

目的:探讨腹膜后纤维化(retroperitoneal fibrosis,RPF)的影像学表现及诊断价值。方法:回顾分析了1996年11月~2006年2月收治的15例腹膜后纤维化患者的X线、B超、CT及MRI表现。结果:RPF的影像学表现为腹膜后弥漫性斑块或肿块及腹膜后脏器的浸润,多伴有肾盂输尿管扩张积水。结论:CT和MRI在腹膜后纤维化的诊断中起重要作用,并能进行分期及疗效监测。X线和B超对RPF的诊断起辅助作用,综合分析X线、B超、CT、MRI影像学表现有助于RPF的诊断。     

自身免疫性胰腺炎的CT和MRI诊断

_目的：探讨 CT 及 MRI 对自身免疫性胰腺炎（AIP）的诊断价值。方法：回顾性分析经实验室检查、穿刺活检、手术或临床激素治疗有效确诊的28例 AIP 患者的临床及影像学资料。21例行 CT 检查,其中17例行 CT 增强扫描;18例行 MRI 检查,其中11例行 MRI 增强扫描,12例行 MRCP 扫描;15例同时行 CT 及 MRI 扫描。结果：CT 与 MRI 可清楚显示胰腺实质及胰腺外脏器的形态、密度或信号改变。胰腺实质表现：胰腺弥漫性增大呈＂腊肠＂样改变,边缘呈＂香蕉皮＂样改变;局限性病变病灶呈＂假肿瘤＂样改变,增强扫描延迟期与正常胰腺实质密度、信号一致。胰腺外脏器表现：胆系改变表现为胆总管及肝内胆管扩张,管壁增厚,增强扫描呈明显强化;肾脏改变表现为 CT 增强扫描动脉期呈斑片状低密度,MRI 呈稍长 T1、稍长 T2信号,延迟期病灶与周围肾实质密度、信号一致;肺内改变表现为肺门区软组织肿块影。结论：自身免疫性胰腺炎 CT 及 MR 表现具有一定特征性,对于该病的诊断及治疗前后疗效的评估具有重要价值。     

MRI findings of pancreatic lymphoma and autoimmune pancreatitis: A comparative study

Purpose

To clarify whether there are differences in MRI findings between pancreatic lymphomas and autoimmune pancreatitis (AIP).

Materials and methods

MRI of 8 patients with pancreatic lymphomas and 21 patients with AIP were retrospectively reviewed. For multifocal pancreatic lymphomas (n = 2) and AIP (n = 4), the largest 2 lesions were evaluated. Ten pancreatic lymphomas and 25 AIP were compared on three bases: the signal intensity on T2-weighted images, internal homogeneity, and presence or absence of capsule-like rim. In 8 lymphomas and 19 AIP, the enhancement pattern on dynamic MRI was compared, as well.

Results

On T2-weighted images, pancreatic lymphomas comprised 5, 5 and 4 lesions with low (iso), slightly high, and moderately high intensity, respectively, while the numbers for AIP were 14, 10, and 1 (P < 0.01). Nine of 10 (90%) lymphomas appeared homogenous, and 11 of 25 (44%) AIP were homogenous (P < 0.05). A capsule-like rim was present in 9 of 25 (36%) AIP, but was not seen in lymphomas (P < 0.05). On dynamic MRI, 18 of 19 (94.7%) AIP showed persistent (n = 5) or delayed enhancement (n = 13), and 6 of 8 (75%) lymphomas showed low intensity without delayed enhancement (P < 0.001).

Conclusion

MRI findings for pancreatic lymphomas and AIP were significantly different, which may be helpful for the differential diagnosis of these two diseases.     

Integrated FDG-PET/CT compared with intravenous contrast-enhanced CT for evaluation of metastatic regional lymph nodes in patients with resectable early stage esophageal cancer

Objective  To assess whether integrated fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) can improve the diagnostic accuracy of metastatic regional lymph nodes (LNs) in esophageal cancer compared with contrast enhanced CT (CECT). Methods  We examined 180 consecutive patients with esophageal cancer by integrated PET/CT between April 2006 and March 2007. Eighteen patients (M:F 14:4) underwent radical esophagectomy after evaluations by PET/CT and CECT of 5–7-mm-thick slices 70–80 s after injection. Regional LNs of esophageal cancer were retrospectively reviewed on CECT images by two blinded evaluators on the basis of the following cutoff sizes: 7 mm for all regional LNs (Protocol A), 10 mm for paratracheal LNs (Protocol B), and 7 mm for others. In addition, the maximum standardized uptake value (SUVmax) on PET/CT was evaluated for positive uptake by LNs. Results  Of 210 LNs excised at surgery, 25 were positive and 185 were negative for metastasis at pathology. The PET/CT images identified 15 true-positive and 184 truenegative LNs, whereas CECT identified 15 true positives and 176 true negatives in Protocol A, and 14 true positives and 180 true negative in Protocol B. The sensitivity, specificity, accuracy, positive, and negative predictive values of PET/CT were respectively 60.0%, 99.5%, 94.8%, 93.8%, and 94.8%, whereas those of CECT were 60.0%, 95.1%, 91.0%, 62.5%, and 94.6% (Protocol A) and 56.0%, 97.3%, 92.4%, 73.7%, and 94.2% (Protocol B). A comparison of the two CECT protocols revealed fewer false-positive LNs in Protocol B, but slightly lower sensitivity in Protocol B than in Protocol A. Substantial numbers of false-positive LNs were determined by CECT in the paratracheal regions (6 of 9, 66.7%) and CECT revealed central necrosis in 4 of 15 (26.7%) true-positive LNs > 1.8 cm. The mean SUVmax on PET/CT was 2.9 (range 1.7–5.5) in true-positive LNs. The smallest LN metastasis detectable by PET/CT was 6 mm. Conclusions  Integrated PET/CT improves the PPV of regional LNs when compared with CECT.     

Sacral insufficiency fracture detected by FDG-PET/CT: Report of 2 cases

We report 2 cases of sacral insufficient fracture detected by FDG-PET/CT. In case 1, a 79-year-old female patient with malignant lymphoma, who had recent lumbago, received FDG-PET/CT examination. Vertical linear FDG uptake medial to bilateral sacro-iliac joint was observed on FDG-PET and a fracture line corresponding to FDG uptake was observed in bone window of CT images. In case 2, an 81-year-old male patient with colon cancer, who also complained of lumbago, received FDG-PET/CT examination. Vertical linear FDG uptake medial to bilateral sacro-iliac joint and horizontal uptake which connects vertical line (H-shaped) was demonstrated and CT also demonstrated a fracture line corresponding to FDG uptake. H-shaped high intensity area corresponding to FDG uptake was observed on T2-weighted image of MRI. On bone scintigraphy, H-shaped uptake was also observed. Like bone scintigraphy, typical H-shaped FDG uptake may be diagnostic in sacral insufficiency fracture. Adding CT information to FDG-PET, that is, assessing SIF with FDG-PET/CT may be useful when atypical findings are observed.     

Peritoneal tuberculosis with elevated serum CA125 mimicking peritoneal carcinomatosis on F-18 FDG-PET/CT

18F-fluorodeoxyglucose positron emission tomography (F-18 FDG-PET) plays an important role in differentiating benign from malignant tumors. However, some false-positive findings, such as tuberculosis, may occur. We report a case referred for F-18 FDG whole-body PET computed tomography (PET/CT) scan owing to an elevated serum cancer antigen 125 (CA125). An FDG-PET/CT scan showed multiple hypermetabolic foci in the mesentery and peritoneum with further increase of FDG uptake on the delayed scan, mimicking peritoneal carcinomatosis. Subsequent laparoscopic biopsy showed granulomatous inflammation, and tuberculosis polymerase chain reaction showed a positive result. Serum CA125 returned to normal following treatment with anti-tuberculosis drugs. Peritoneal tuberculosis should be considered as a differential diagnosis in a tuberculosis endemic region.     

The effect of oral contrast on large bowel activity in FDG-PET/CT

PURPOSE: The purpose of this study was to determine the effect of oral contrast on FDG uptake in the colon and to determine the normal distribution of FDG in the colon. METHODS: Sixty patients (30 patients in no contrast group and 30 patients in the received contrast group) underwent FDG-PET/ CT scans. The pattern of FDG uptake was classified into 5 patterns (diffuse, segmental, single-nodular, multi-nodular, and other) in 5 segments (ascending, transverse, descending, and rectosigmoid colon). SUVs of the no oral contrast group were examined. The ratios of FDG uptake patterns were compared in the received contrast group and no contrast group to evaluate the effect of oral contast. The effect of attenuation correction on the uptake pattern was evaluated by comparison of the attenuation-corrected and non-attenuation-corrected PET images. RESULTS: In the no contrast group, there was no significant uptake in 72 segments (59%) and a diffuse pattern was seen in 29 segments (24%), most frequently in the ascending colon and descending colon. A segmental pattern was seen in 15 segments (13%), most frequently in the rectosigmoid colon. A single-nodular pattern was seen in 3 segments (3%) and multi-nodular pattern in 1 segment (1%). A nodular pattern was seen only in the ascending colon. SUVmax of the ascending colon and that of the rectosigmoid colon were significantly higher than those of the transverse and descending colon. The frequencies of diffuse, multi-nodular and 'other' patterns were significantly higher in the received contrast group than in no contrast group. There was no significant difference between the frequency of the segmental pattern or the single nodular pattern in the two groups. There was no significant difference between the uptake patterns with attenuation correction and those without attenuation correction in either the received contrast group or no contrast group. CONCLUSION: Normal FDG uptake in the large bowel may show various degrees and patterns of uptake among the colonic segments. Oral contrast agent can cause focal or diffuse increased FDG uptake, which may be induced not only by the high CT density of oral contrast but also by an accelerated physiologic reaction of the large bowel.