Imaging of indeterminate pancreatic cystic lesions: A systematic review

BackgroundPancreatic cystic lesions are an increasing problem and investigation of these cysts can be fraught with difficulty. There is currently no gold standard for diagnosis or surveillance. This review was undertaken to determine the present reliability of the characterisation, assessment of malignant potential and diagnosis of pancreatic cystic lesions using available imaging modalities.MethodsA Medline search using the terms ‘pancreatic’, ‘pancreas’, ‘cyst’, ‘cystic’, ‘lesions’, ‘imaging’, ‘PET’. ‘CT’, ‘MRI’ and ‘EUS’ was performed. Publications were screened to include studies examining the performance of CT, MRI, MRCP, EUS and 18-FDG PET in the determination of benign or malignant cysts, cyst morphology and specific diagnoses.ResultsNineteen studies were identified that met the inclusion criteria. 18-FDG PET had a sensitivity and specificity of 57.0–94.0% and 65.0–97.0% and an accuracy of 94% in determining benign versus malignant cysts. CT had a sensitivity and specificity of 36.3–71.4% and 63.9–100% in determining benign disease but had an accuracy of making a specific diagnosis of 39.0–44.7%. MRI had a sensitivity and specificity of 91.4–100.0% and 89.7% in assessing main pancreatic duct communication.ConclusionCT is a good quality initial investigation to be used in conjunction with clinical data. MRCP can add useful information regarding MPD communication but should be used judiciously. PET may have a role in equivocal cases to determine malignancy. Further examination of CT-PET in this patient group is warranted.     

Magnetic resonance imaging of malignant lymphoma

Computed tomography (CT), (18)F-fluorodeoxyglucose (FDG)-PET and the hybrid FDG-PET/CT are the most commonly used diagnostic tools for the initial staging and treatment response assessment of malignant lymphomas. MRI techniques such as whole-body MRI and diffusion-weighted imaging may be good radiation-free alternatives to FDG-PET/CT, which may be particularly relevant for children. Diffusion-weighted imaging is characterized by high sensitivity for the detection of lesions and allows quantitative assessment of diffusion that may aid in the evaluation of malignant lymphomas. This article will review the value of these emerging MRI techniques for the staging and response assessment of malignant lymphoma. Furthermore, we will discuss some additional imaging techniques that are the subject of ongoing research and may have potential for future clinical application.     

Intracystic hemorrhage of a simple liver cyst mimicking a biliary cystadenocarcinoma

Simple liver cysts are rarely complicated by intracystic hemorrhage. We encountered a case of simple liver cyst that was morphologically similar to biliary cystadenocarcinoma, which was complicated by asymptomatic intracystic hemorrhage and successfully treated by right lobectomy. A large cystic lesion of the liver was detected in a 57-year-old woman during a mass screening health check. Abdominal ultrasonography (US) revealed that the cystic lesion, containing many hyperechoic papillary structures, occupied almost the entire region of the right hepatic lobe. In addition, a round mural nodule, measuring approximately 5 cm in diameter, was detected in the cystic wall. Abdominal computed tomography (CT) revealed that the inner part of the cystic lesion showed homogeneous low density, but CT did not show the round nodule detected by US. On T1-weighted sequence of magnetic resonance imaging (MRI), the lesion showed homogeneous high signals, together with a low-signal tumorous lesion in the cystic wall. T2-weighted sequence of MRI showed unhomogeneous high signals, together with high signals in the tumorous part. These findings did not exclude the possibility of a malignant cystic tumor, such as biliary cystadenocarcinoma. Therefore, right lobectomy was performed. Histological examinations of resected tissue specimens revealed that the lesion was a liver cyst containing a large amount of blood clot, and that the tumorous lesion detected by US and MRI was a large mass of blood clot which was partly liquefied. This case indicates the diagnostic importance of the morphological discordance between CT and US or MRI findings for liver cyst containing a large amount of blood clot. Received: May 7, 2001 / Accepted: December 27, 2001 Reprint requests to: Y. Kitajima     

Ultrasound and color Doppler imaging for kidney and urinary tract tumors

When a renal mass is suspected, conventional ultrasound and color Doppler imaging are often used for initial assessment. Ultrasound screening has many advantages over contrast-enhanced CT and MRI, such as accessibility, low costs, and no need for intravenous iodine contrast administration or ionizing radiation. Sonography is very helpful to distinguish cystic from solid lesions and to monitor the growth and structural pattern of cysts. Detection of small renal carcinoma of less than 3 cm in diameter is limited, however, and small tumors are detected by conventional ultrasound only in 67-79% of cases. In fact, small renal malignancies may have an echogenicity similar to the normal renal parenchyma. In these cases it is very hard to distinguish the tumor, particularly when there is no evident disarrangement of the normal renal contours and no extension into the central renal complex. Renal cell carcinoma can also be hypo- or hyperechoic and indistinguishable from renal adenoma/oncocytoma or angiomyolipomas, which are commonly described as hyperechoic masses. In other words, the pattern and ultrasound characteristics of renal masses often overlap between benign and malignant tumors. A diagnosis of a malignant cystic lesion requires evidence of multiple, thickened internal septa, calcifications, vascularity, and parietal nodularity. When a solid lesion does not show the typical appearance of a simple cyst (a round anechoic lesion with a smooth well-defined wall, without internal debris, and showing increased through-transmission), further evaluation with contrast-enhanced CT or MRI is necessary. Contrast-enhanced ultrasound (CEUS) improves the sensitivity for detection of small renal masses. Compared to CT, CEUS is able to better visualize the number of septa, the septum and wall thickness, the presence of a solid component, and enhancement in some cases, resulting in upgrading of the Bosniak classification and affecting treatment planning.     

Diagnostic imaging of liver tumours. Current status

Nowadays, contrast enhanced ultrasound (CEUS) is an imaging technique equivalent to multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) for the detection and characterization of focal liver lesions. These methods have comparable sensitivity and specificity in differentiating a liver lesion as "benign" or "malignant". For benign lesions, CEUS is the recommended method of the choice. In unclear cases, or if CEUS is not available, MRI or CT are the methods of the second choice. If a benign tumor remains unclear, then a needle biopsy is recommended. In the case of a malignant tumor, it is necessary to use a second imaging technique besides CEUS. In addition to the detection and characterization of a liver tumor, CT and MRI provide information on the extrahepatic spread of a tumor, particularly into the lung or retroperitoneum. The rapid development of surgical and interventional approaches requires accurate information on the character and number of malignant liver lesions. Therefore, the combined use of CEUS and MDCT or MRI currently represents the most modern and optimal standard of imaging. The standardization of CT and MRI protocols has increased the general diagnostic level of these images. Adequate training and a certificate for the use of CEUS is recommended in order to maintain the high diagnostic level of this method (EFSUMB guide lines). An optimal interdisciplinary imaging strategy for focal liver lesions minimises unnecessary invasive or potentially harmful imaging and reduces health costs.     

Bildgebende Diagnostik von Lebertumoren

Nowadays, contrast enhanced ultrasound (CEUS) is an imaging technique equivalent to multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) for the detection and characterization of focal liver lesions. These methods have comparable sensitivitiy and specifity in differentiating a liver lesion as “benign” or “malignant”. For benign lesions, CEUS is the recommended method of the choice. In unclear cases, or if CEUS is not available, MRI or CT are the methods of the second choice. If a benign tumor remains unclear, then a needle biopsy is recommended. In the case of a malignant tumor, it is necessary to use a second imaging technique besides CEUS. In addition to the detection and characterization of a liver tumor, CT and MRI provide information on the extrahepatic spread of a tumor, particularly into the lung or retroperitoneum. The rapid development of surgical and interventional approaches requires accurate information on the character and number of malignant liver lesions. Therefore, the combined use of CEUS and MDCT or MRI currently represents the most modern and optimal standard of imaging. The standardization of CT and MRI protocols has increased the general diagnostic level of these images. Adequate training and a certificate for the use of CEUS is recommended in order to maintain the high diagnostic level of this method (EFSUMB guide lines). An optimal interdisciplinary imaging strategy for focal liver lesions minimises unnecessary invasive or potentially harmful imaging and reduces health costs.     

Pancreatic Cysts and Guidelines

Pancreatic cysts, especially incidental asymptomatic ones seen on noninvasive imaging such as CT or MR imaging, remain a clinical challenge. The etiology of such cysts may range from benign cysts without any malignant potential such as pancreatic pseudocysts and serous cystadenomas to premalignant or frankly malignant cysts such as mucinous cystic neoplasms, intraductal papillary mucinous neoplasms, cystic degeneration associated with solid tumors such as pancreatic ductal adenocarcinoma or pancreatic endocrine neoplasms, and solid pseudopapillary neoplasms. The clinical challenge in 2017 is to accurately preoperatively diagnose them and their malignant potential before deciding about surgery, surveillance or doing nothing. This review will focus on the currently available clinical guidelines for doing so.     

Hepatic angiomyolipoma pre-operatively diagnosed by imaging

An asymptomatic patient with pre-operatively diagnosed solitary angiomyolipoma is reported. The tumour was a well defined, fat density mass on computerized tomography (CT) and magnetic resonance imaging (MRI), and a hyperechoic nodule with a sharp margin on ultrasonography (US). The lesion was hypervascular on arteriography and CT during hepatic angiography. Chemical shift MRI confirmed the fat component within the lesion. Although a review of the literature shows this tumour to be rare and difficult to differentiate from a malignant lesion pre-operatively, the pre-operative diagnosis of angiomyolipoma is considered feasible when the characteristic findings as described here are present.     

Imaging evaluation of the liver in oncology patients: A comparison of techniques

The liver is commonly affected by metastatic disease. Therefore, it is essential to detect and characterize liver metastases, assuming that patient management and prognosis rely on it. The imaging techniques that allow non-invasive assessment of liver metastases include ultrasonography, computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET)/CT, and PET/MRI. In this paper, we review the imaging findings of liver metastases, focusing on each imaging modality’s advantages and potential limitations. We also assess the importance of different imaging modalities for the management, follow-up, and therapy response of liver metastases. To date, both CT and MRI are the most appropriate imaging methods for initial lesion detection, follow-up, and assessment of treatment response. Multiparametric MRI is frequently used as a problem-solving technique for liver lesions and has evolved substantially over the past decade, including hardware and software developments and specific intravenous contrast agents. Several studies have shown that MRI performs better in small-sized metastases and moderate to severe liver steatosis cases. Although state-of-the-art MRI shows a greater sensitivity for detecting and characterizing liver metastases, CT remains the chosen method. We also present the controversial subject of the "economic implication" to use CT over MRI.     

Imaging of congenital esophageal cysts in adults

The radiologic imaging of esophageal cysts (EC) in adults is described. These rare cysts, often detected incidentally on routine chest radiographs, seldom produce symptoms, but they may cause precordial sensations, arrhythmias, and dysphagia. They may also bleed and become malignant. As surgical excision is the treatment of choice, the preoperative diagnosis must be exact. For this, magnetic resonance imaging (MRI) or endoscopic ultrasound seem to be the imaging methods of choice even if a plausible diagnosis can be advanced on computed tomography (CT). Chest x-ray or esophagus roentgenogram have little differential diagnostic value.     

Evaluation of hepatic cystic lesions

Hepatic cysts are increasingly found as a mere coincidence on abdominal imaging techniques, such as ultrasonography (USG), computed tomography (CT) and magnetic resonance imaging (MRI). These cysts often present a diagnostic challenge. Therefore, we performed a review of the recent literature and developed an evidence-based diagnostic algorithm to guide clinicians in characterising these lesions. Simple cysts are the most common cystic liver disease, and diagnosis is based on typical USG characteristics. Serodiagnostic tests and microbubble contrast-enhanced ultrasound (CEUS) are invaluable in differentiating complicated cysts, echinococcosis and cystadenoma/cystadenocarcinoma when USG, CT and MRI show ambiguous findings. Therefore, serodiagnostic tests and CEUS reduce the need for invasive procedures. Polycystic liver disease (PLD) is arbitrarily defined as the presence of > 20 liver cysts and can present as two distinct genetic disorders: autosomal dominant polycystic kidney disease (ADPKD) and autosomal dominant polycystic liver disease (PCLD). Although genetic testing for ADPKD and PCLD is possible, it is rarely performed because it does not affect the therapeutic management of PLD. USG screening of the liver and both kidneys combined with extensive family history taking are the cornerstone of diagnostic decision making in PLD. In conclusion, an amalgamation of these recent advances results in a diagnostic algorithm that facilitates evidence-based clinical decision making.     

Intraductal papillary mucinous tumor of the pancreas: computerized tomography and magnetic resonance imaging features

The aim of this study was to analyze the computerized tomography (CT) and magnetic resonance imaging (MRI) features of intraductal papillary mucinous tumor (IPMT) of the pancreas. The cases of eight patients with pathologically proven IPMT (1 papillary hyperplasia, 7 adenocarcinoma) of the pancreas were retrospectively reviewed. There were five men and three women with ages ranging from 42 to 82 years. Imaging studies included six thin-section dynamic CT scans, seven MRI scans, one MR cholangiopancreatography scan, and two endoscopic retrograde cholangiopancreatography scans. There was only one benign IPMT, which presented as a unilocular cyst in the pancreatic body with no mural nodules and no dilatation of the main pancreatic duct (MPD). All seven patients with malignant IPMT had multilocular cysts with papillary projections in the pancreatic head and/or uncinate process accompanied by dilated MPD (5 diffuse, 2 segmental). Communication between the cystic lesions and the MPD were evident in all seven patients. One patient had small mural nodules in the branch ducts of the pancreatic body and five had a bulging papilla with a patulous orifice. A mass effect resulting in biliary obstruction was shown in one patient. One patient had a ruptured cyst with mucin leakage into the right anterior pararenal space following sono-guided aspiration. In conclusion, the main imaging feature of IPMT in our patients was a multilocular cyst with papillary projections located in the pancreatic head and uncinate process. Although CT and MRI cannot differentiate mucin content from pancreatic juice, communication between the cystic lesion and the dilated MPD and a bulging papilla with a patulous orifice are characteristics of IPMT.     

Molecular biomarkers have the potential to improve the diagnostic work-up of pancreatic cystic lesions

Pancreatic cysts are increasingly diagnosed due to the widespread use of cross-sectional imaging, and some of these lesions harbor malignant potential. Mucinous cystic neoplasms and intraductal papillary mucinous neoplasms are the major premalignant cystic neoplasms of the pancreas. A variety of diagnostic tools are used to predict the malignant potential of these cysts, but specificity and sensitivity are limited. Thus, many patients undergo unnecessary operations for benign cysts. Balancing the risks of watchful waiting with those of operative management is key in managing these lesions. During the last decade, genetic changes of pancreatic cysts have been examined extensively to estimate their malignant potential. In this review, we provide an overview of the latest molecular and genetic aspects of pancreatic cysts and how they may contribute to the differential diagnosis in patients with pancreatic cystic neoplasms.     

Diagnostik des Nierenzellkarzinoms

The frequent use of imaging modalities has led to a rising number of incidentally detected renal cell carcinomas (RCC). Especially the incidence of small asymptomatic renal masses has significantly increased. Due to considerable progress in disease management of RCC, for example new approaches in nephron-sparing surgery for localized tumors less than 4?cm, cross-sectional imaging is required for a more detailed preoperative characterization of renal masses. Most renal tumors (80%) are diagnosed incidentally by ultrasound examination (US). The detection rate can even be improved using duplex sonography or contrast-enhanced ultrasound (CEUS). If an accurate diagnosis is not possible with ultrasound, computed tomography (CT) examination may help to further qualify complicated cystic lesions of the kidneys. Computed tomography (CT) is still the reference standard for diagnosing primary tumor extent as well as for tumor staging. The most important criterion for assessing malignancy in a renal lesion is the evidence supplied by contrast-enhancement. Computed tomography also facilitates a differentiation of benign solid masses, such as angiomyolipomas and adenomas from malignant renal tumors and even the diagnosis of lymphomas is possible. Magnetic resonance imaging offers a better soft tissue contrast and is superior to a CT examination in diagnosing possible venous involvement and in the evaluation of inferior vena cava tumor thrombi. The differentiation of RCC subtypes, angiomyolipomas as well as distinguishing simple from complex renal cysts is also possible. The grading of different RCCs can be preoperatively estimated using dynamic contrast-enhanced MRI or measuring perfusion and diffusion within renal tumors. Due to a low sensitivity positron emission tomography/computed tomography (PET/CT) is not part of the routine diagnostic management for RCC. Nevertheless it plays an important role in the diagnosis of distant metastases and postoperative surveillance of advanced renal tumors. In some cases a complementary application of radiological imaging modalities, such as US, CT, MRI or PET/CT is required for an accurate differentiation of renal masses and for the diagnosis of RCCs.     

Imaging findings in neurocysticercosis

The diagnosis of neurocysticercosis was greatly improved by the introduction of computed tomography (CT) and magnetic resonance imaging (MRI). These techniques demonstrate the number and topography of lesions, their stage of involution, and the degree of inflammatory reaction of the host against the parasites and have largely replaced previous radiological procedures such as plain roentgenograms, pneumoencephalograms, cerebral angiography and myelography. In general, MRI provides better image detection and definition. The possibility of multiplanar reconstruction of images, its capability to visualize the posterior fossa without bone artifacts, and its high contrast resolution (far superior to that of CT) allow MRI to recognize many forms of cysticercosis not visualized on CT. However, the costs of MRI are high and the equipment is scarcely available in many endemic countries, and its sensitivity for the detection of calcified lesions is poor. CT remains the best screening neuroimaging procedure for patients with suspected neurocysticercosis, and MRI is the imaging modality of choice for the evaluation of patients with intraventricular cysticercosis, brainstem cysts and small cysts located over the convexity of cerebral hemispheres. Its better image definition also suggests that MRI is superior to CT in the follow-up of the patients after therapy.     

MRI characterization of 124 CT-indeterminate focal hepatic lesions: evaluation of clinical utility

Objective. To evaluate the diagnostic yield of MRI performed for characterization of focal hepatic lesions that are interpreted as indeterminate on CT. Patients and methods. In a retrospective investigation, 124 indeterminate focal hepatic lesions in 96 patients were identified on CT examinations over 5 years from 1997 to 2001. All patients had MRI performed for the liver within 6 weeks of their CT examination. CT and MR images were reviewed independently by two separate groups of two radiologists. The value of MRI in characterizing these lesions was assessed. Diagnoses were confirmed based on histology, characteristic imaging features, and clinical follow-up. Results. MRI definitely characterized 73 lesions (58%) that were indeterminate on CT. MRI was accurate in 72/73 of these lesions. MRI could not definitely characterize 51 lesions (42%). Ten lesions were not visualized on MRI, and follow-up imaging confirmed that no lesion was present in eight of these cases (pseudolesions). Conclusion. MRI is valuable for the characterization of indeterminate focal hepatic lesions detected on CT.     

Appraisal of needle-based confocal laser endomicroscopy in the diagnosis of pancreatic cysts

Nearly 2.5% of cross-sectional imaging studies will report a finding of a cystic pancreatic lesion. Eventhough most of these are incidental findings, it remains very concerning for both patients and treating clinicians. Differentiating and predicting malignant transformation in pancreatic cystic lesions is clinically challenging. Current evaluation of suspicious cystic lesions includes a combination of radiologic imaging, endoscopic ultrasound(EUS) and cyst fluid analyses. Despite these attempts, precise diagnostic stratification among nonmucinous, mucinous, and malignant cystic lesions is often not possible until surgical resection. EUS-guided needle based confocal laser endomicroscopy(n CLE) for evaluation of pancreatic cysts is emerging as a powerful technique with remarkable potential. Though limited imaging data from 3 large clinical trials(INSPECT, DETECT and CONTACT) are currently the reference standard for n CLE imaging, nonetheless these have not been validated in large studies. The aim of this review article is to review the evolving role of EUS-guided n CLE in management of pancreatic cystic lesions in terms of its significance, adverse events, limitations, and implications.     

先天性支气管囊肿CT及MRI诊断价值

目的探讨先天性支气管源性囊肿(bronchogenic cysts, BC)的计算机断层扫描(computerized tomography, CT)及磁共振成像(magnetic resonance imaging, MRI)诊断。 方法回顾性分析经手术病理证实的23例BC患者的CT及MRI表现和临床资料。 结果纵隔内11例，其中前纵隔4例，中纵隔3例，后纵隔4例，均为单发，呈类圆形，边缘光滑，密度均匀；其中一例合并出血和感染，平扫表现为稍高密度影、CT值约为50～60 HU，增强扫描可见轻度强化；其余纵隔型BC均表现为平扫低密度影，CT值约为10～30 HU，增强扫描未见明显强化。肺内10例，均为单发类圆形或椭圆形病灶，其中3例为含气囊腔，7例为囊性低密度影，增强扫描未见明显强化。颅内2例，位于左侧额部，MRI表现为椭圆形T1WI低信号，T2WI高信号影，一例其后份可见片状T1WI、T2WI稍高信号影，增强扫描均未见强化。 结论支气管囊肿的CT及MRI表现有一定的相对特征性，结合临床综合分析可提高诊断正确率。     

Complementary results of computed tomography and magnetic resonance imaging of the heart and coronary arteries: a review and future outlook

MR and CT imaging are emerging as promising complementary imaging modalities in the primary diagnosis of CAD and for the detection of subclinical atherosclerotic disease. For the detection or exclusion of significant CAD, both cardiac CT (including coronary calcium screening and non-invasive coronary angiography), and cardiac MRI (using stress function and stress perfusion imaging) are becoming widely available for routine clinical evaluation. Their high negative predictive value, especially when combining two or more of these modalities, allows the exclusion of significant CAD with high certainty, provided that patients are selected appropriately. The primary goal of current investigations using this combined imaging approach is to reduce the number of unnecessary diagnostic coronary catheterizations, and not to replace cardiac catheterization altogether. For the diagnosis of obstructive coronary atherosclerosis and for screening for subclinical disease, CT and MRI have shown potential to directly image the atherosclerotic lesion, measure atherosclerotic burden, and characterize the plaque components. The information obtained may be used to assess progression and regression of atherosclerosis and may open new areas for diagnosis, prevention, and treatment of coronary atherosclerosis. Further clinical investigation is needed to define the technical requirements for optimal imaging, develop accurate quantitative image analysis techniques, outline criteria for image interpretation, and define the clinical indications for both MR or CT imaging. Additional studies are also needed to address the cost effectiveness of such a combined approach versus other currently available imaging modalities.     

Characterization of focal liver lesions with SonoVue(R)-enhanced sonography: International multicenter-study in comparison to CT and MRI

AIM: To evaluate in a multicenter study whether the sonographic characterization of focal liver lesions can be improved using SonoVue(R)-enhancement; and to compare this method with computed tomography (CT) and magnetic resonance imaging (MRI). METHODS: One hundred and thirty four patients with one focal liver lesion detected in baseline ultrasound (US) were examined with conventional US, contrastenhanced US ( n = 134), contrast-enhanced CT ( n = 115) and/or dynamic contrast-enhanced MRI ( n = 70). The lesions were classified as malignant, benign or indeterminate and the type of lesion was determined.The final diagnosis based on the combined information of all imaging examinations, clinical information and histology ( n = 32) was used. Comparisons were made to see whether the addition of contrast-enhanced US led to the improvement of the characterization of doubtful focal liver lesions. RESULTS: In comparison with unenhanced US, SonoVue(r) markedly improves sensitivity and specificity for the characterization (malignant/benign) of focal liver lesions. In comparison with CT and/or dynamic MRI, SonoVue(r) -enhanced sonography applied for characterization of focal liver lesions was 30.2% more sensitive in the recognition of malignancy and 16.1% more specific in the exclusion of malignancy and overall 22.9% more accurate. In the subgroup with confirmative histology available ( n = 30), sensitivity was 95.5% (CEUS), 72.2% (CT) and 81.8% (MRI), and specificity was 75.0% (CEUS), 37.5% (CT) and 42.9% (MRI). The sensitivity and specificity of CEUS for the identification of focal nodular hyperplasia (FNH) and hemangiomas was 100% and 87%, resulting in an accuracy of 94.5%. CONCLUSION: SonoVue(r)-enhanced sonography emerges as the most sensitive, most specific and thus most accurate imaging modality for the characterization of focal liver lesions.