Role of diffusion MRI and proton magnetic resonance spectroscopy in characterization of ovarian neoplasms

Introduction

Adnexal masses are a common clinical problem and considered as the leading indication for gynecological surgery. The ovary and adnexal structures are relatively difficult to image with any technology. Magnetic resonance spectroscopy (MRS) can detect metabolic changes. As molecular changes often precede morphologic alterations, sensitivity is expected to improve by MRS. Diffusion weighted magnetic resonance imaging (DW-MRI) is sensitive to molecular diffusion which is due to random microscopic translational motion of molecules (known as Brownian motion). In the event of morphologic evaluation of cystic ovarian tumors, whether benign or malignant, DW-MR imaging and calculated apparent diffusion coefficient (ADC) values would be useful for evaluation.

Purpose

The aim of this study is to evaluate the role of diffusion MRI & proton magnetic resonance spectroscopy (H-MRS) in diagnosis of ovarian neoplasms.

Subjects and methods

This study included 20 patients, their ages ranged from 20 to 72 years. In all cases, diagnosis was proven by surgical and pathological examination. Trans-abdominal ultrasound (n = 20) and trans-vaginal ultrasound (n = 11) were included in our routine protocol to obtain baseline information preceding MR examination. The routine MR examination protocol included: T1WI, T2WI, and post contrast fat suppressed T1WI. Diffusion weighted imaging (DWI) was done to all patients at b0, b500, b1000 and ADC values were calculated. MRS was performed in all cases using multi-voxel point resolved surface coil spectroscopy (PRESS sequence) for volume localization.

Results

Fourteen cases (70%) had benign ovarian masses while the remaining six cases (30%) had malignant masses. High lipid peak was detected in all three cases of mature cystic teratoma. All cases of simple serous cysts showed choline and creatine signals that were higher than the average noise level but lower than the two fold higher noise level. Sharp choline peak was detected in all malignant ovarian masses (except a case of metastases under chemotherapy) as well as the case of fibroma. Creatine signal was detected in all benign and malignant masses except two cases of mature cystic teratoma and cases of endometrioma. Lactate signal was detected only in cases of hemorrhagic cysts, mature cyst teratoma and one case of endometrioma and not obtained in any of malignant lesions except dysgerminoma. High NAA signal was detected in dysgerminoma and all three cases of mature cystic teratomas. The mean Cho/Cr ratio was significantly higher in malignant than benign ovarian masses (<0.05), there was no significant difference in mean and lowest ADC values between malignant and benign lesions.

Conclusion

Proton MRS using Cho/Cr ratio added useful information for the diagnosis of different ovarian neoplasms. Direct visual assessment of DWI of ovarian lesions is not useful in differentiating benign from malignant ovarian lesions; determining the threshold of the ADC for diagnosing cystic ovarian tumors is difficult because of their large variance. Further experience with a larger and more biologically variable range of tumors is recommended.     

Immature teratoma of the ovary: correlation of MR imaging and pathologic findings

The objectives of this study were to describe MR imaging findings of immature teratoma and to correlate imaging findings with histopathologic findings. The MR findings of ten patients (age range 12–29 years, mean age 19.0 years) with pathologically proven immature teratoma were retrospectively reviewed for tumor size, presence and characteristics of fatty content, presence and characteristics of solid components, and presence of ascites and implants. The MR findings were compared with gross (n=3) and microscopic (n=10) findings. Comparisons between relative amounts of solid components and histologic grades were evaluated by Spearman rank-order correlation. On MR images all lesions appeared to be fat-containing tumors with solid components consisting of numerous cysts of various sizes. Solid tissue exhibited a wide variety of signal intensities on T2-weighted images. Punctate foci of fat were identified in all lesions, whereas fatty fluid was observed only in two. Predominant fluid content exhibited signal intensities similar to simple fluid in nine lesions. Ascites was observed in six lesions, and peritoneal dissemination in three. Pathologic studies confirmed scattered foci of adipose tissue in the solid portions of all cases, and revealed numerous cystic structure formations in these solid components. The correlation coefficient between the amount of solid tissue and the tumor grade was not significant (r_s=0.266). The MR images of immature teratoma tended to show aqueous fluids and the solid components consisting of numerous cysts with punctate foci of adipose tissue, whereas predominant fluid is sebaceous fluid in the vast majority of mature cystic teratomas. Electronic Publication     

CT findings of mature cystic teratoma with malignant transformation: comparison with mature cystic teratoma

Purpose

To evaluate the imaging findings of mature cystic teratoma with malignant transformation (malignant teratoma) compared with the corresponding mature cystic teratoma (benign teratoma).

Materials and methods

This study enrolled 1325 patients with 12 malignant teratomas and 1313 benign teratomas. We compared the computed tomographic (CT) findings of eight malignant teratomas and 15 benign teratomas; both groups were matched in terms of tumor size (>9.9 cm) and patient age (>45 years). The CT images were retrospectively evaluated with focus on soft tissue components; size, border (regular or irregular), the presence or absence of nodular formation, enhancement, the angle formed between the soft tissue components and the inner wall of the cyst (acute or obtuse), and transmural growth as well as metastasis including lymphadenopathy and disseminated disease. Using the Fischer's Exact test, each evaluating parameter was compared between the two groups.

Results

Soft tissue components were observed in 75% (six of eight) of malignant teratomas and in 33% (five of fifteen) of benign teratomas; 100% (six of six) of soft component in malignant teratomas had a nodular formation and none of soft component in benign teratomas showed nodular formation; 83% (five of six) of soft component in malignant teratomas had enhancement as well as an obtuse angle between the soft tissue components and the inner wall of the cyst. None of soft component in benign teratomas showed enhancement and 20% (one of five) of soft component in benign teratomas had an obtuse angle; 33% (two of six) of soft component in malignant teratomas showed transmural growth, 13% (one of eight) of malignant teratoma showed lymphadenopathy, and 38% (three of eight) showed disseminated disease. None of benign teratomas showed transmural growth, lymphadenopathy, or disseminated disease. A statistically significant difference between patients with and without malignant transformation was seen in terms of nodular formation, obtuse angle, and enhancement of the soft tissue components (P<.05).

Conclusion

Malignant teratoma is characterized by the following imaging findings: the presence of a nodular forming and enhancing soft tissue component, an obtuse angle between the soft tissue and the inner wall of the cyst, as well as extracapsular tumor growth with extension into adjacent structures or metastasis. Therefore, we can differentiate malignant teratoma from benign teratoma using CT findings.     

Ovarian teratomas: tumor types and imaging characteristics.

Ovarian teratomas include mature cystic teratomas (dermoid cysts), immature teratomas, and monodermal teratomas (eg, struma ovarii, carcinoid tumors, neural tumors). Most mature cystic teratomas can be diagnosed at ultrasonography (US) but may have a variety of appearances, characterized by echogenic sebaceous material and calcification. At computed tomography (CT), fat attenuation within a cyst is diagnostic. At magnetic resonance (MR) imaging, the sebaceous component is specifically identified with fat-saturation techniques. The US appearances of immature teratoma are nonspecific, although the tumors are typically heterogeneous, partially solid lesions, usually with scattered calcifications. At CT and MR imaging, immature teratomas characteristically have a large, irregular solid component containing coarse calcifications. Small foci of fat help identify these tumors. The US features of struma ovarii are also nonspecific, but a heterogeneous, predominantly solid mass may be seen. On T1- and T2-weighted images, the cystic spaces demonstrate both high and low signal intensity. Familiarity with the US, CT, and MR imaging features of ovarian teratomas can aid in differentiation and diagnosis.     

卵巢畸胎瘤的MRI诊断

目的:分析卵巢畸胎瘤的MRI表现,提高MRI诊断的准确性.方法:搜集经手术和病理证实的68例共70个卵巢畸胎瘤,对其MRI表现作回顾性分析.结果:70个畸胎瘤中,成熟性畸胎瘤65个,未成熟性畸胎瘤4个,卵巢甲状腺肿1个.65个成熟性畸胎瘤均为囊性,其中单房46个(71％),双房11个(17％),多房5个(8％),不完全...     

The significance of added ADC value to conventional MR imaging in differentiation between benign and malignant ovarian neoplasms

Purpose

To highlight the role of ADC value measurement in differentiating benign from malignant ovarian tumors.

Materials and methods

Twenty patients with ovarian neoplasms underwent conventional MRI including ADC value calculation before surgery. Retrospective analysis of the pathological specimen with lesion morphology, signal characteristics, enhancement criteria and correlation with the appearance at DWI followed by ADC value measurement were obtained.

Results

Twenty patients with ovarian mass lesions were included. They were divided into purely solid, purely cystic and complex solid/cystic lesions. All solid malignant lesions showed diffusion restriction as well as the wall and septations of most malignant cystic lesion however, except one case. All benign lesions did not display diffusion restriction in DWI. The best cut off value of ADC to discriminate between benign and malignant lesions was 0.9 with specificity of 100%, sensitivity of 88.9%, NPV of 75%, PPV of 100% and accuracy of 91.7%.

Conclusion

Addition of ADC value measurement to conventional MRI increases its specificity from 78.6% to 85.7% which could be useful in differentiating benign from malignant lesions.     

Diagnostic accuracy of diffusion-weighted imaging in differentiating benign from malignant ovarian lesions

Purpose

To clarify the diagnostic accuracy of diffusion‐weighted imaging (DWI) in differentiating benign from malignant ovarian lesions.

Materials and Methods

We retrospectively analyzed magnetic resonance images of 123 ovarian lesions in 119 patients. We defined lesions with abnormal signal intensity as malignancy and assessed the location of abnormal intensity within the lesions on DWI. We also assessed the mean and lowest apparent diffusion coefficient (ADC) values of the solid portion for each ovarian lesion.

Results

The majority of malignant ovarian tumors and mature cystic teratomas, and almost half of the endometriomas, showed abnormal signal intensity on DWI, whereas most fibromas and other benign lesions did not. The main locations of abnormal signal intensity were solid portions in malignant ovarian tumors, cystic components suggestive of keratinoid substances and Rokitansky protuberance in mature cystic teratomas, and intracystic clots in endometriomas. On DW imaging, receiver‐operating characteristic analysis yielded mean Az values of 0.703. There was no significant difference in mean and lowest ADC values between malignant and benign lesions.

Conclusion

DWI of ovarian lesions and ADC values of the solid component are not useful for differentiating benign from malignant ovarian lesions. This knowledge is essential in avoiding misinterpretation in the diagnosis of ovarian lesions. J. Magn. Reson. Imaging 2008;28:1149–1156. © 2008 Wiley‐Liss, Inc.     

Ovarian fibromas: MR imaging findings with emphasis on intratumoral cyst formation

Purpose

The purpose of this study was to assess MR imaging findings of ovarian fibromas with emphasis on intratumoral cyst formation.

Materials and methods

MR images with a 1.5-T unit obtained in 17 consecutive patients (age range, 18–87 years; mean age, 58 years) with 17 histologically proven ovarian fibromas were retrospectively reviewed for the size, configuration, signal intensity of solid components, and presence of cystic degeneration and edema within tumor. Size, number, and location of intratumoral cysts were also assessed.

Results

The maximum diameter of tumors ranged from 3.3 to 19.1 cm (mean, 10.9 cm). Seven (41%) tumors were multinodular. On T2-weighted images, solid components of tumors were heterogeneously mixed hypo- and hyperintensity in 16 (94%) tumors. Nine (53%) tumors demonstrated cysts and 16 (94%) demonstrated edema within tumor. The maximum diameter of the largest cysts ranged from 1.0 to 13.2 cm (mean, 6.4 cm), and the number of cysts per tumor ranged from 1 to 60 (mean, 15.6). Of the nine tumors with cystic formation, the predominant location of the cysts was peripheral in five (56%), exophytic in two (22%), central (11%) in one, and diffuse in one (11%).

Conclusion

Peripheral or exophytic cyst formation may be characteristic MR imaging features with ovarian fibromas.     

卵巢未成熟畸胎瘤的CT、MRI表现(附8例报告)

目的探讨卵巢未成熟畸胎瘤的CT、MRI表现。资料与方法对8例经手术和病理证实的卵巢未成熟畸胎瘤的CT、MRI资料进行回顾性分析。结果本组8例均表现为囊实性肿块,实性成分较大。3例CT平扫实性部分表现为高低混杂密度,内见多发小囊状低密度影、"碎片"状脂肪密度影及多发散在高密度钙化灶,增强扫描呈"破絮"状强化;5例MRI实性部分表现为高低混杂信号,内见多发大小不等长T1、长T2信号囊状影、散在碎片状短T1、长T2信号脂肪组织以及不规则长T1、长T2信号实性软组织影,4例增强扫描见实性部分呈破絮状强化。结论卵巢未成熟畸胎瘤有较特征性的CT、MRI表现。     

Accumulation of gallium-67 within mature and immature teratoma in pediatric patients: investigation for the uptake mechanism

OBJECTIVE: We encountered cases of mature and immature teratoma with positive uptake of (67)Ga. The objective of this study is to investigate the mechanism of (67)Ga accumulation within mature and immature teratomas by comparing the findings of gallium scan, computed tomography (CT), and autoradiography of surgical specimens with the pathological findings. METHODS: The subjects comprised 14 children who underwent surgical resection for intra-abdominal mature and immature teratomas, which were histologically proved to be of the mature and immature subtype. Their age ranged from 24 days to 14 years. The origins of the mature teratomas consisted of seven ovaries including one bilateral case, two retroperitoneal, and two sacrococcygeal regions. The origins of the immature teratomas were retroperitoneum in two cases, an ovary and a sacrococcygeal region. Complete surgical excision was feasible in all children. They underwent both gallium scan and CT prior to surgery. Single-photon emission computed tomography was added in some cases. For two gallium-positive cases, radiography and scintigraphy (autoradiography) of the resected specimen were performed. RESULTS: Of the 14 children, 5 (one with immature and four with mature subtype) showed positive (67)Ga uptake within tumors, which originated from the retroperitoneum in the 3 boys, and from the ovary in the 2 girls. All had typical CT findings of teratoma, including calcifications, fat components, cystic areas, and solid parts. (67)Ga accumulation in the four mature teratomas appeared discretely strong, and was considered to correspond with intralesional calcifications. However, in the remaining one immature teratoma, the gallium distribution was diffuse within the tumor. The comparison between radiography and autoradiography of the resected mature teratomas confirmed the correlation between the intralesional calcifications and areas of (67)Ga accumulation. CONCLUSIONS: A high-uptake ratio of (67)Ga in benign teratoma was indicated. A close correlation between gallium scan and CT helps to ascertain whether (67)Ga uptake results from malignant and/or immature elements, or mature tissue components.     

Malignant struma ovarii: Case report of an unusual ovarian tumor with CT imaging

Struma ovarii is categorised as a monodermal type of mature teratoma and consists primarily of thyroid tissue. It is an uncommon ovarian tumor, with non–specific clinical, and imaging findings. The majority of struma ovarii are benign and are typically associated with mature cystic teratomas. A small proportion of struma ovarii may undergo malignant transformation, with papillary carcinoma the most common type of malignancy. The criteria used to identify a malignant change in struma ovarii are identical to those used to evaluate the thyroid gland. Nevertheless, due to the rarity of struma ovarii, imaging diagnostic criteria, and subsequent management are not clearly defined. This case report describes a 41-year-old female patient who presented with rapid abdominal enlargement over a period of 1 month, accompanied by elevation of the tumor marker CA-125. Based on these clinically findings, ovarian cancer was suspected. The patient underwent a total abdominal hysterectomy with bilateral salpingo-oophorectomy. Histopathology results revealed a malignant struma ovarii.     

Tumor disease and associated congenital abnormalities on prenatal MRI

Objective

Fetal tumors can have a devastating effect on the fetus, and may occur in association with congenital malformations. In view of the increasing role of fetal magnetic resonance imaging (MRI) as an adjunct to prenatal ultrasonography (US), we sought to demonstrate the visualization of fetal tumors, with regard to congenital abnormalities, on MRI.

Materials and methods

This retrospective study included 18 fetuses with tumors depicted on fetal MRI after suspicious US findings. An MRI standard protocol was used to diagnose tumors judged as benign or malignant. All organ systems were assessed for tumor-related complications and other congenital malformations. Available US results and histopathology were compared with MRI.

Results

There were 13/18 (72.2%) benign and 5/18 (27.8%) malignant tumors diagnosed: a cerebral primitive neuroectodermal tumor in 1/18, head–neck teratomas in 4/18; ventricular rhabdomyomas in 4/18; a cardiac teratoma in 1/18; a hepatoblastoma in 1/18; neuroblastomas in 2/18; a cystic hemorrhagic adrenal hyperplasia in 1/18; a pelvic leiomyoma in 1/18; sacrococcygeal teratomas in 3/18. Tumor-related complications were present in 13/18 (72.2%) cases; other congenital abnormalities in 3/18 (16.7%). MRI diagnosis and histology were concordant in 8/11 (72.7%) cases. In 6/12 (50%) cases, US and MRI diagnoses were concordant, and, in 6/12 (50%) cases, additional MRI findings changed the US diagnosis.

Conclusion

Our MRI results demonstrate the visualization of fetal tumors, with frequently encountered tumor-related complications, and other exceptional congenital abnormalities, which may provide important information for perinatal management. Compared to prenatal US, MRI may add important findings in certain cases.     

卵巢生殖细胞肿瘤的CT诊断

目的探讨卵巢生殖细胞肿瘤的CT表现特点.方法回顾性分析经手术病理证实的37例46个卵巢生殖细胞肿瘤的CT资料,结合病理讨论其CT表现特点.结果本组卵巢生殖细胞肿瘤中,畸胎瘤43个,内胚窦瘤2个,混合性生殖细胞瘤1个.对卵巢畸胎瘤,CT和B超的敏感性均为100%,特异性分别为93.02%和58.14%.30例38个成熟囊性畸胎瘤,CT明确诊断27例35个,均含有脂肪密度区,5个见脂液平面,11个有浮球征,16个有钙化或牙齿状影.5个未成熟畸胎瘤呈囊性或实性为主肿块,肿块内均见多发斑点状钙化和少许小片状脂肪密度影,其中1例实性成分内见盘曲的带状略低密度影.内胚窦瘤呈囊性1例,呈实性为主1例,实性肿块内见较大的不规则低密度坏死区.混合性生殖细胞瘤呈实质性,不规则形.结论卵巢畸胎瘤和内胚窦瘤的CT表现具有各自的特点,尤其是畸胎瘤,具有特征性表现,与B超相比,CT是更好的检查方法.     

肿瘤内成分构成比对骶尾部畸胎瘤成熟度分型的价值

目的：探讨小儿骶尾部畸胎瘤瘤内成分构成比在骶尾部畸胎瘤成熟度分型方面的作用。方法：对28例骶尾部畸胎瘤患儿进行MRI扫描,用手动勾画体积测量法测量瘤内实性成分、脂肪和瘤内囊变体积构成比,对照术后病理,进行t检验统计学分析。结果：成熟型畸胎瘤组（A组）瘤内实性成分含量范围是（19.48±11.82）%,未成熟型及恶性畸胎瘤组（B组）瘤内实性成分构成比范围是（66.07±30.64）%,两组差异有显著性意义（P=0.000）,以41.63%作为阈值推测肿瘤成熟度,敏感度为100%,特异度为75%,准确率为89.3%,误诊率为25%,漏诊率为0%;A组瘤内脂肪含量构成比为（48.51±24.97）%,B组瘤内脂肪含量构成比为（3.97±2.45）%,两组差异有显著性意义（P=0.000）,并将10.61%作为阈值推测肿瘤的成熟度,敏感度为87.5%,特异度为100%,准确率为92.9%,误诊率为0%,漏诊率为12.5%;A组瘤内囊变成分体积构成比为（22.80±18.65）%,B组瘤内囊变体积构成比为（30.14±30.13）%,两组差异无显著性意义（P=0.434）。结论：小儿骶尾部畸胎瘤瘤内实性和脂肪成分构成比对判断肿瘤成熟度均有显著性意义,以脂肪含量灵敏度更大,特异性更高,漏诊率更小;但两者正确率相当。瘤内囊变成分构成比在小儿骶尾部畸胎瘤成熟度分型方面无显著性意义。     

How to manage the patients with unsatisfactory results after ethanol ablation for thyroid nodules: role of radiofrequency ablation

Purpose

Although ethanol ablation (EA) is effective in the treatment of cystic thyroid nodules, it is less effective in nodules with solid component. Therefore refractory cases with solid component require another treatment modality such as radiofrequency ablation (RFA), which is effective in both solid and cystic thyroid nodules. We prospectively evaluated the efficacy of additional RFA and factors related to volume reduction in patients showing unsatisfactory results after a single session of EA.

Materials and methods

Of 94 patients with predominantly cystic thyroid nodules who underwent EA, 20 patients underwent additional RFA because of incompletely resolved clinical problems (symptomatic score reduction <50%) and presence of residual solid component at 1-month follow-up on ultrasonography. Improvement of clinical symptoms and nodule volume reduction were evaluated 6 month later. We evaluated factors related to nodule volume reduction after EA and RFA.

Results

RFA after a single session of EA was effective in reducing mean symptom score from 4.8 to 1.1 (p < 0.001), mean cosmetic score from 3.5 to 1.4 (p < 0.001) and mean nodule volume from 11.3 to 0.9 mL (p < 0.001). The only independent factor related to volume reduction after EA was the presence of a solid component (p < 0.001), and EA was less effective in nodules when solid component >20% (p = 0.001). We identified no factors related to volume reduction after RFA.

Conclusion

RFA is effective in treatment of benign predominantly cystic thyroid nodules in patients whose clinical problems were incompletely resolved after EA.     

Mature and immature ovarian teratomas: CT, US and MR imaging characteristics

Ovarian teratomas (OTs) are the most common germ cell neoplasm. They include mature cystic teratomas, monodermal teratomas (neural tumors, struma ovarii, carcinoid tumors) and immature teratomas. Teratomas are the most common benign ovarian neoplasms in women less than 45 years old. OTs are usually characterized by ultrasound (US) and magnetic resonance (MR) whereas they are usually an incidental finding on CT. The purpose of this paper is to review the most common types of teratomas and to describe CT, US and MR imaging features of the various types of mature and immature OTs.     

Imaging features of unusual lesions and complications associated with ovarian mature cystic teratoma

Mature cystic teratoma (MCT) is a common neoplasm of the ovary that typically contains mature tissues of ectodermal, mesodermal, and endodermal origin. This tumor tends to affect younger women, its presentation ranges from pure cystic mass to complex solid cystic mass, and the detection of intratumoral fat component is the key diagnostic imaging feature. MCT can be associated with various complications and it demonstrates a wide spectrum of imaging findings. Associated complications include rupture, torsion, malignant transformation, and gliomatosis peritonei. MCT may also have unusual imaging features that can lead to misdiagnosis. These features may expand the differential diagnosis to include immature teratoma, monodermal teratoma, mature cystic teratoma with minimal or no fat, and collision tumor. The aim of this article was to highlight and describe the imaging features of unusual ovarian MCT lesions, and the complications associated with ovarian MCT.     

Can diffusion weighted imaging distinguish between benign and malignant solid or predominantly solid gynecological adnexal masses?

Objective

To determine the benefit of DWI in diagnosis of benign and malignant solid or predominantly solid gynecological adnexal or ovarian masses.

Material and Methods

This study is carried out on 23 patients with histologically proven solid or predominantly solid adnexal or ovarian masses out of which 5 cases (21.8%) have benign and 18 cases (78.2%) have malignant neoplasms. Among these 19 cases (82.6%) have unilateral disease and 4 cases (17.4%) have bilateral disease which was metastatic ovarian carcinoma.

Result

On DWI, high signal intensity is noted in malignant lesion more frequently than in benign lesion. (P < 0.001) in adnexal lesions, while in ovarian lesions (P = 0.001).The differentiation between benign and malignant adnexal lesions revealed no significant difference in the apparent diffusion coefficient (ADC) value (P = 0.22).

Conclusion

DWI is a helpful tool in differentiation between predominantly solid and solid benign and malignant adnexal lesions because there is an increased frequency of higher signal intensity (diffusion restriction) in malignant lesions.     

Pancreatic multicenter ultrasound study (PAMUS)

Aim

To describe the typical CEUS pattern of pancreatic lesions and to evaluate the diagnostic accuracy of Contrast-enhanced ultrasound (CEUS) in their characterization.

Materials and methods

All US and CEUS examinations of focal pancreatic masses performed in six centers during a period of five years were reviewed. Inclusion criteria were: focal pancreatic mass pathologically proved, visible at ultrasound (US) and studied with CEUS. All lesions were then evaluated for size, aspect and enhancement pattern. Sensitivity, specificity, positive and negative predictive values with 95% CIs were calculated to define diagnostic accuracy of CEUS in respect to pathology. Diagnostic confidence of US and CEUS, discerning between benign and malignant lesions, were represented by using ROC (receiver operating characteristics) curves. Agreement was evaluated by means of k statistics.

Results

1439 pancreatic lesions were included. At CEUS the lesions were divided into solid (89%) and cystic (12%) masses and classified into six and eight categories, respectively. Among the solid lesions, adenocarcinomas were characterized with an accuracy of 87.8%. Among the cystic lesions, cystic tumors were diagnosed with an accuracy of 97.1%. ROC curve area increased from 0.637 for US to 0.877 for CEUS (p < 0.0001). Inter-observer agreement was slightly higher for solid (k = 0.78) than cystic (k = 0.62) lesions. In none of the centers side effects were reported.

Conclusion

CEUS is accurate in the characterization of pancreatic lesions. CEUS should be considered as a complementary imaging method for pancreatic lesions characterization.     

Subtraction images: A really helpful tool in non-vascular MRI

Background

Subtraction imaging is a technique whereby an unenhanced T1-weighted sequence is digitally subtracted from the identical sequence performed after gadolinium administration.

Aim of the work

This study will highlight the role of subtraction imaging for non-vascular MRI applications.

Subjects and methods

The study included 40 patients presenting with lesions in different parts of the body, that are initially hyperintense on T1W sequences.We used post-processing software (Osirix) to digitally subtract the pre-enhancement from the post enhancement sequences.

Results

Based on subtraction imaging findings 5 patients were diagnosed with intraocular melanomas, two patients were diagnosed with hemorrhagic cysts in the masseter muscle , two patients were diagnosed with hemorrhagic cysts in the parotid gland, two patients were diagnosed with dysplastic hepatic nodules, 5 patients were diagnosed with post-ablation necrosis following hepatocellular carcinoma (HCC) treatment, two patients showed recurrent HCC after chemoembolisation, 3 patients showed chemoembolised HCC without recurrence, 4 patients showed intraluminal gall bladder sludge, 4 patients showed hemorrhagic renal cysts, one patient showed solid papillary neoplasm of the pancreas, 6 patients showed chocolate ovarian cysts, two patient showed ovarian cystadenoma and two patients showed ovarian cystadenocarcinoma.

Conclusion

Subtraction MRI is very helpful tool in non-vascular MRI applications.