Role of new radiation techniques (ultrasonography, computed tomography, and magnetic resonance imaging) in the diagnosis of incidentally discovered adrenal masses

The authors analyze the current views of incidentally discovered adrenal masses and the potentialities of ultrasound study (US), computed tomography (CT), and magnetic resonance imaging (MRI) in their detection and presents the US, CT, and MRI symptoms of different incidentally discovered adrenal masses. Due to the availability and almost extensive application of US apparatuses, they define the importance of US screening of the adrenal region and emphasize the capacities of echographic differentiation of cystic and solid adrenal masses in patients with different diseases of the abdomen and retroperitoneal space. The authors also note the basic role of CT and MRI in the specified topical diagnosis of retroperitoneal space lesions and in the presumption of the morphological structure of some tumor and tumoroid (hyperplasia-type) adrenal changes.     

肿瘤/肝脏比值在~(18)F-FDG符合线路SPECT/CT显像在肺癌诊断中的价值

目的:探讨18F-FDG符合线路SPECT/CT显像在肺癌病灶的检测能力以及肿瘤/肝脏比值对肺部良恶性病灶及胸部小病灶诊断的临床价值。方法:回顾性分析2011年6月至2013年4月期间于西安交通大学第一附属医院行18F-FDG符合线路SPECT/CT显像的肺癌疑诊患者41例CT测量肺部原发病灶最大直径4.16±2.81厘米(最小直径1.3厘米,最大直径16厘米),以病理结果作为判断标准,通过t检验及接受者操作特征曲线(receiver operating characteristic,ROC)研究18F-FDG符合线路SPECT/CT显像对肺部病灶、肺及纵膈小病灶的诊断价值。结果:18F-FDG符合线路SPECT/CT显像肺部良恶性病灶的肿瘤/肌肉(T/N)、肿瘤/肝脏(T/L)比值差异均具有显著统计学意义(P0.01),T/L比值在肺部良恶性病灶和肺及纵膈最大横径小于3 cm的病灶ROC曲线的曲线下面积分别为0.857、0.810,均大于T/N比值相应的ROC曲线下面积(分别为0.825、0.760)。T/N=3.5为界值时,诊断肺部病灶的灵敏度为90%,特异度为71.4%,准确度为0.614;诊断最大横径小于3 cm病灶的灵敏度为70%,特异度为80%,准确度为0.50。T/L=2.3时诊断肺部病灶的灵敏度为80%,特异度为85.7%,准确度为0.657。T/L=1.6时诊断最大横径小于3 cm病灶的灵敏度为90%,特异度为80%,准确度为0.70。结论:T/N=3.5为界值时,对于肺部病灶及肺及最大横径小于3 cm病灶良恶性的鉴别能力较好。T/L比值对于肺部良恶性病灶和肺及纵膈最大横径小于3 cm的病灶诊断价值均高于传统常用的T/N比值,具有较高的准确性,可以良好的应用于18F-FDG符合线路SPECT/CT显像对肺癌的诊断中。     

Diagnostic Challenges in Adrenocortical Carcinoma: Recommendations for Surveillance after Surgical Resection of Selected Adrenal Nodules

ObjectiveTo discuss challenges in the diagnosis of adrenocortical carcinoma and to suggest surveillance measures after removal of selected adrenal nodules.MethodsWe present the case of a 65-year-old man with worsening hypertension and new-onset hypokalemia attributed to primary hyperaldosteronism due to a 3-cm right adrenal nodule.ResultsA laparoscopic right adrenalectomy was performed, and the histologic diagnosis was a benign adenoma. The patient’s hypertension and hypokalemia improved postoperatively but recurred 8 months later, and florid Cushing’s syndrome developed. Magnetic resonance imaging showed an 8-cm mass in the right adrenal bed and multiple hepatic metastatic lesions. Fine-needle biopsy confirmed the presence of adrenocortical carcinoma.ConclusionDespite a comprehensive biochemical, radiologic, and histologic assessment, the diagnosis of adrenocortical carcinoma can be missed. Particularly, we caution against undue reliance on the initial tumor size. We recommend that abdominal imaging be performed every 3 months for the first year and every 6 months for the second year after surgical removal of selected adrenal nodules. (Endocr Pract. 2007;13:636-641)     

Asymptomatic adrenal tumor; 386 cases in Japan including our 7 cases

To clarify the indication of surgery in incidentally discovered asymptomatic adrenal masses, we analyzed 386 Japanese cases, 379 cases reported in Japan during the past 25 years (from 1964 to 1988) and 7 cases from our own experience. From a total of 460 patients, we carefully selected 379 patients satisfying our criterion of the absence of symptoms and signs suggestive of active hormone over-secretion as described in each case report. From the Japanese series, there was a high incidence of pheochromocytoma patients (20 of 37 patients) who had no symptoms and signs but had high plasma or urine catecholamines. Scintigraphy with 131I-meta-iodo-benzyl-guanidine was useful in the diagnosis of pheochromocytoma. For the other asymptomatic adrenal tumors, except for myelolipoma and adrenal cyst, differential diagnosis between malignant and benign adrenal lesions by imaging procedures such as whole body computed tomography (CT), ultrasonography (US), adrenocortical scintigraphy, and angiography was not always possible. In addition, among the 109 patients with cortical tumors whose hormonal data were reported, no clear-cut differentiation of malignant tumor from benign by means of these data could be obtained. Since 1980 whole body CT scanner and high resolution US scanner have become widely available, and there have been 283 cases of asymptomatic adrenal tumors who satisfied our criterion. Cortical carcinomas smaller than 3 cm and 6 cm in diameter account for 3.8% and 6.6%, respectively, of the total of 101 cases of cortical carcinoma, cortical adenoma, ganglioneuroma, and hemangioma during this period. The size of the smallest cortical carcinoma with metastasis was 2 cm in diameter in this series. Pre-operatively, an adrenocortical carcinoma 2.8 cm in diameter in our patient could not be diagnosed as such by imaging techniques and measurement of plasma hormones. These findings suggest that an adrenal mass larger than 3 cm should be removed and a patient with a smaller cortical tumor should be carefully followed up.     

Adrenal Incidentalomas, 2003 to 2005: Experience After Publication of the National Institutes of Health Consensus Statement

ObjectiveTo determine the clinical outcomes and follow-up imaging characteristics for incidentally discovered adrenal nodules at a large metropolitan health care center, as well as compliance with National Institutes of Health guidelines for the evaluation of these lesions.MethodsBetween October 2003 and June 2005, computed tomographic (CT) scanning performed at Harvard Vanguard Medical Associates detected 165 adrenal nodules (incidentalomas) in 129 patients without extra-adrenal malignant lesions or evidence of adrenal hyperfunction. Nodule characteristics, including size at baseline, change in size at follow-up, CT attenuation values, biochemical data, and clinical outcomes, were analyzed.ResultsOf the 165 adrenal incidentalomas, 96% were smaller than 4 cm. When attenuation values were determined, 65% were low (< 10 Housfield units). Ninetyeight patients (76%) with 142 nodules (86% of all incidentalomas) had at least 1 follow-up CT scan. Of these 142 lesions, 20 (14%) changed significantly in size (grew or became smaller by 0.5 cm or more). Growth was detected within 12 months in 5 of the 7 lesions (71%) that grew. For 95% of patients, the adrenal nodule did not necessitate intervention, including change in medication or surgical treatment. Biochemical studies for adrenal hyperfunction were done in 39 of the overall 129 patients (30%), but in only 20 of 109 patients (18%) not seen by endocrinologists.ConclusionMost adrenal incidentalomas are benign, nonfunctional tumors. Growth typically occurs within 12 months after detection. Despite the 2002 National Institutes of Health guidelines, 82% of patients at our medical center with adrenal nodules who were not seen by endocrinologists did not have hormonal testing. More physician education about the evaluation of incidentalomas should be provided, and prospective studies to establish the appropriate duration of follow-up should be conducted. (Endocr Pract. 2008;14:279-284)     

Characterization of Incidental Liver Lesions: Comparison of Multidetector CT versus Gd-EOB-DTPA-Enhanced MR Imaging

As a result of recent developments in imaging modalities and wide spread routine medical checkups and screening, more incidental liver lesions are found frequently on US these days. When incidental liver lesions are found on US, physicians have to make a decision whether to just follow up or to undergo additional imaging studies for lesion characterization. In order to choose the next appropriate imaging modality, the diagnostic accuracy of each imaging study needs to be considered. Therefore, we tried to compare the accuracy of contrast-enhanced multidetector CT (MDCT) and Gd-EOB-DTPA-enhanced MRI for characterization of incidental liver masses. We included 127 incidentally found focal liver lesions (94 benign and 33 malignant) from 80 patients (M∶F = 45∶35) without primary extrahepatic malignancy or chronic liver disease. Two radiologists independently reviewed Gd-EOB-DTPA-enhanced MRI and MDCT. The proportion of confident interpretations for differentiation of benign and malignant lesions and for the specific diagnosis of diseases were compared. The proportion of confident interpretations for the differentiation of benign and malignant lesions was significantly higher with EOB-MRI(94.5%–97.6%) than with MDCT (74.0%–92.9%). In terms of specific diagnosis, sensitivity and accuracy were significantly higher with EOB-MRI than with MDCT for the diagnosis of focal nodular hyperplasia (FNH) and focal eosinophilic infiltration. The diagnoses of the remaining diseases were comparable between EOB-MRI and MDCT. Hence, our results suggested that Gd-EOB-MRI may provide a higher proportion of confident interpretations than MDCT, especially for the diagnosis of incidentally found FNH and focal eosinophilic infiltration.     

Adrenal Cortical Carcinoma With Late Pulmonary Metastases Causing Clinicical Cushing’s Syndrome: Case Report With Immunohistochemical Analysis Of Steriodogenic Enzyme Production

ObjectiveTo present a case of pulmonary metastases from adrenocortical carcinomas (ACC) that were secreting fully-functional cortisol resulting in clinical Cushing’s syndrome and to compare the steroidogenic enzyme expression in the primary tumor and lung.MethodsWe analyzed and summarized the patient’s medical history, physical examination results, labora tory data, imaging studies, and histopathologic results. The original tumor and the pulmonary metastases were then immunohistochemically evaluated for steroidogenic enzymes.ResultsInitial endocrinological workup revealed hyperandrogenism and adrenocorticotropic hormone (ACTH) independent Cushing’s due to a 4 cm left adrenal mass. The patient was initially diagnosed with an adrenal adenoma. Four years later, the patient developed recurrent Cushing’s syndrome. Repeat magnetic resonance imaging (MRI) showed no adrenal masses; however, chest computed tomography (CT) showed multiple bilateral lung nodules and biopsy revealed metastases of adrenal origin. Upon immunohistochemical analysis, side chain cleavage, 17α hydroxylase, 3β hydroxysteroid dehydrogenase, and 21 hydroxylase immunoreactivity were detected in both the original and pulmonary metastatic lesions with patterns of disorganized steroidogenesis. Dehydroepiandrosterone sulfotransferase (DHEA-ST) immunoreactivity was detected in the original tumor but not in the lung metastases.ConclusionThis case demonstrates some inter esting features of ACC that pose challenges to its management, including the difficulties in establishing the pathologic diagnosis, the potential for fullyfunctional steroidogenesis even in late metastases, and the plasticity of steroidogenic potential in tumor cells. (Endocr Pract. 2012;18:e138-e143)     

Current views on imaging of adrenal tumors.

Anatomical imaging modalities (such as computed tomography [CT] or magnetic resonance imaging [MRI]) and functional imaging modalities (that is, nuclear medicine) are used in the evaluation of adrenal glands. The use of CT (unenhanced, followed by contrast-enhanced) evaluation is the cornerstone of imaging of adrenal tumors. Attenuation values of less than 10 Hounsfield units at unenhanced CT are practically diagnostic for adenomas, while attenuation values of greater than 10 HU are not diagnostic of metastatic disease since non-metastatic disease is also a possibility. When lesions cannot be characterized adequately with CT, MRI evaluation (with T1 and T2-weighted sequences and chemical shift and fat-suppression refinements) is sought. Functional nuclear medicine imaging can be of utility in the evaluation of adrenal masses, more particularly for lesions not adequately characterized with CT and MRI. Nuclear medicine techniques are based on physiological and pathophysiological processes (cellular metabolism, tissue perfusion and local synthesis, uptake, storage of hormones and their receptors). Functional imaging aids initial preoperative staging, diagnostic evaluation of suspicious lesions, identification of metastatic or recurrent tumors, refining prognosis, and deciding on and predicting responses to therapy. [ (131)I]-6-iodomethyl norcholesterol scintigraphy can differentiate adenomas from carcinomas. Pheochromocytomas appear as areas of abnormal/increased [ (131)I]- and [ (123)I]-meta-iodobenzylguanidine uptake. Our experience has shown that [ (18)F]-fluorodopamine is an excellent agent for localizing adrenal and extra-adrenal pheochromocytomas.     

The value of 99mTc-MIBI scan in the detection of malignancy potential of hypermetabolic thyroid incidentalomas of 18F-FDG PET/CT

Aim of the studyIncreasingly use of PET/CT leads to discovery of incidental findings. Hypermetabolic thyroid nodules are one of the unexpected lesions in PET/CT imaging with an increased risk of thyroid cancers. Our study aims to determine the malignant potential of incidentally detected 18F-FDG avid thyroid nodules by using Tc-99m MIBI imaging.Materials and methodsPET/CT scans were performed for nonthyroidal purposes and were evaluated for the presence of hypermetabolic thyroid nodules. Tc-99m MIBI scans and ultrasonography-guided fine needle aspiration biopsies were subsequently performed for all patients.ResultsPrimary thyroid malignancies were identified in 25% of patients with increased focal FDG uptake at definitive diagnosis. Among the patients with FDG avid thyroid nodules, Tc-99m MIBI scan showed true-positive results in all thyroid carcinomas (n:7) with a 36.3% (4/11) false-positivity rate. In three patients with indeterminate cytology results, Tc-99m MIBI scan findings were also negative. The sensitivity, specificity, positive predictive value of Tc-99m MIBI scan in predicting the malignancy of FDG-positive thyroid nodules were 100%, 77%, 63.6%, respectively.ConclusionThe implementation of ^99mTc-MIBI scan performed by dual phase and SPECT/CT modality might be a helpful cost-effective approach in addition to FNAB in patients with ¹⁸F-FDG-positive thyroid nodules and indeterminate cytology to improve the patients’ prognosis and reduce unnecessary thyroid operations with associated use of FNAB.     

肺淋巴瘤的CT表现

目的：肺部淋巴瘤可为原发,亦可为其他部位淋巴瘤的肺部浸润,临床上很少见。准确的影像学诊断对于采取及时的治疗措施具有重要意义,然而该病影像学表现复杂多变,容易与多种其他肺部病变混淆,以往文献对于肺部淋巴瘤的CT影像特征性表现报道不多,本文旨在探讨肺部淋巴瘤的特征性CT表现,以提高该痛影像诊断的准确率。方法：回顾性分析17例病理证实的肺淋巴瘤患者CT资料,分析特征性影像表现。结果：17例中多发者13例,单发者4例。叶段性或斑片状实变影13例,多发结节影13例,肿块状实变影8例,具有两种以上病灶的12例。特征性的征象有：病灶密度均匀（88．2％,15／17）、病灶边缘模糊（82．3％,14／17）、支气管气相（64．7％,11／17）、支气管血管柬增厚（58．8％,10／17）和CT血管造影征（41．2％,7／17）,对诊断有较大意义。结论：肺部淋巴瘤CT表现以多发、多形态病变居多,具有一定特征性影像表现,密度均匀、边缘模糊的实变、团块或结节影,具有支气管气相、支气管血管束增厚、增强扫描可见CT血管造影征等表现可高度提示本病的可能,结合病史、临床表现以及实验室检查,可提高本病的诊断准确率,对于及时开展有效的治疗措施、改善患者预后具有重要的临床意义。     

直径小于1 cm孤立性肺结节的18F-FDG PET/CT诊断研究进展

孤立性肺结节的鉴别诊断一直是胸部影像学的研究热点。早期且准确地鉴别肺内小结节的良恶性,对于患者治疗方案的确定以及随访情况的评估均具有重要的临床意义。~(18)F-FDG PET/CT在鉴别诊断恶性肿瘤方面具有明显优于其他传统检查的高特异性和高敏感性,其公认的恶性肿瘤的诊断阈值是最大化标准摄取值(maximum standard uptake value, SUVmax)为2.5,然而部分临床数据显示一些直径小于1 cm的恶性肺结节的SUVmax数值小于2.5。因此在早期研究中,~(18)F-FDG PET/CT在诊断直径较小的肺结节的其临床价值仍存在争议。为了尽量降低SUVmax的测量误差,提高~(18)F-FDG PET/CT诊断的准确率,衍生出了许多SUVmax辅助诊断方法以及优化的重建算法、放射性显像剂的联合应用等手段。本文将对~(18)F-FDG PET/CT鉴别诊断直径小于1 cm孤立性肺结节的研究进展进行综述。     

Potentialities of computed tomography and ultrasound in diagnosis of hormonally active adrenal diseases: results of comparison CT and US with operative adn histological data

The data given in the paper suggest that X-ray computed tomography (CT) is highly effective in detecting all types of hormonally active adrenal abnormalities. CT used in hormonally active adrenal diseases yielded data on major quantitative and qualitative (primarily densitometric) criteria that could be used in assessing the images of the adrenal area in these patients. Ultrasound study (USS) made at the first stage of topical diagnostic searches was of informative value in detecting adrenal tumor lesions, the technique being highly sensitive in the diagnosis of adrenal pheochromocytomas and adenocarcinomas, but less informative in the detection of hormonally active adrenocortical adenomas (aldesterone-producing ones in particular) than CT. The diagnosis of various adrenocortical hyperplasies and the differentiation of hyperplastic and tumor forms of hypercorticoidism are a prerogative of CT that substantially supplements USS findings in such cases.     

Change in Adrenal Mass Size as a Predictor of a Malignant Tumor

ObjectiveTo assess the value of adrenal mass absolute growth, growth rate, and percentage growth rate on serial imaging for distinguishing benign from malignant adrenal masses.MethodsWe retrospectively reviewed the Cleveland Clinic medical record data on 136 adrenalectomies or biopsies in 132 patients with 2 imaging studies performed more than 2 months apart (during 1997 to 2008).ResultsThere were 111 benign (81.6%) and 25 malignant (18.4%) adrenal masses. With use of receiver operating characteristic curve analysis, all 3 aforementioned growth measures showed similar levels of discrimination for the entire study group as well as for the subgroups with 3 to 12 months of follow-up (n = 75 masses) and noncontrast computed tomography Hounsfield units > 10 or not reported (n = 111 masses). After adjustment for other factors, the 3 growth measures remained statistically significant predictors of a malignant tumor. The absolute growth cutoff value of 0.8 cm had the highest sum of sensitivity and specificity of 72% and 81.1%, respectively. We could not identify an adrenal mass growth cutoff value to provide 100% sensitivity or specificity to confirm or exclude the presence of a malignant lesion. In 3 patients with metastatic lesions, no growth or a decrease in mass size during a period of 4 to 36 months was observed.ConclusionIn this study, the largest with surgical histopathology findings as the “gold standard” for diagnosis, change in adrenal mass size was a significant predictor of a malignant tumor. Nevertheless, we could not identify an adrenal mass growth cutoff value for reliable confirmation or exclusion of a malignant lesion. Change in adrenal mass size should be used in conjunction with other imaging and clinical characteristics when surgical resection is being considered. (Endocr Pract. 2010;16:577-587)     

探讨CT技术在肺结节疾病诊断中的应用

目的：探讨CT技术在肺结节疾病诊断中的应用。利用CT技术提供的影像学特征,及时准确的诊断肺结节疾病,从而更具体更全面的提高对该疾病的认识,减少误诊的发生。方法：回顾性分析我院2010年-2012年确诊的符合相应临床诊治标准的肺结节患者48例的临床资料,通过CT扫描分析其具体的特征表现。结果：在所选的48例中,纵隔淋巴结增大45例,双侧肺门淋巴结增大44例,胸部淋巴结增大患者48例。肺部病变者33例,其中单发结节患者2例,多发结节患者25例,支气管血管束增粗者14例,磨玻璃样影案例者9例,实变案例5例。胸膜病发患者13例。结论：我们通过分析发现,胸部有典型影像学表现形式的肺结节病例诊断较容易,无典型影像学表现的患者诊断较为困难。因此我们认为利用CT技术诊断肺结节疾病具有特异性意义,值得临床医生重视。     

Positron emission tomography (18FDG-PET) in the detection of medullary thyroid carcinoma metastases

INTRODUCTION: Medullary thyroid carcinoma (MTC) is usually more advanced at presentation than differentiated thyroid cancers and often has distant metastases. The primary treatment of MTC is total thyroidectomy and regional lymph node dissection. The efficacy of these procedures has been limited by the aggressiveness of the disease and metastatic spread at the time of surgery. Persistently elevated levels of calcitonin (CT) and carcinoembryonic antigen (CEA) or their increase postoperatively are indicative for residual or recurrent disease. Conventional imaging methods such as ultrasonography, computed tomography, magnetic resonance imaging and MIBI scintigraphy usually fail to find the source of calcitonin. Better imaging properties have been shown by DMSA scintigraphy, somatostatin receptor scintigraphy or by positron emission tomography (PET). The aim of the study was to evaluate the diagnostic accuracy of PET for the localisation of occult MTC in patients after surgery with increased concentrations of CT, in whom conventional imaging procedures have not been successful. MATERIAL AND METHODS: The PET investigation using (18)F-fluoro- 2-deoxy-D-glucose combined with computed tomography ((18)FDG-PET/CT) was performed at the Department of Nuclear Medicine (Oncology Centre in Bydgoszcz) between January and October 2004. In five patients with postoperative calcitonin ranging from 164 to > 2000 ng/l (normal < 10 ng/l) no tumour lesions were found using other imaging methods. RESULTS: In four of five cases, responsible lesions with a higher metabolism of FDG, indicating MTC tissue (remnants or metastases), were localised. In one patient no focus of FDG accumulation was found despite high CT concentration. PET detected tumour manifestations in the neck and the mediastinum in two patients, in the lung and the left adrenal gland in one case and in the neck and the liver in another patient. As a result of surgery for the removal of a residual tumour or metastases the accuracy of diagnosis was confirmed by histopathology in all four cases and a decrease in CT and CEA levels was observed in 3/4 cases. The metabolic imaging findings by PET/CT ensured that the surgery on these patients was successful. CONCLUSIONS: For the detection of occult residual or metastatic MTC lesions, (18)FDG-PET is a valuable procedure in imaging diagnostics.     

Pheochromocytoma in Patients Suspected of Harboring Adrenal Meta stasis: Management and Clinical Predictors

ObjectiveTo study clinical management of patients with suspected adrenal metastasis and to assess whether there are clinical predictors of pheochromocytoma in this patient population.MethodsIn this retrospective cross-sectional study, we reviewed medical records of patients who had adrenalectomy for adrenal lesions or had adrenal biopsy performed between January 1997 and July 2007 in a large academic hospital. Patients who harbored adrenal masses that were suspected of being metastases were identified on clinical findings. Pathologic diagnosis, demographic data, clinical history, imaging studies, and laboratory test results were reviewed and compared among patients whose adrenal mass was determined to be metastasis, adenoma, or pheochromocytoma.ResultsOne-hundred sixty-three patients had adrenalectomy or had adrenal biopsy during the study period. Thirty patients (18%) had adrenal masses that were suspected of being metastases. Of the adrenal masses, 18 (60%) were metastases, 8 (27%) were benign adenomas, and 4 (13%) were pheochromocytomas. Eleven patients (37%) had biochemical testing for pheochromocytoma. Adrenal biopsy was performed without biochemical testing for pheochromocytoma in 9 patients (30%), including 2 subsequently found to have this tumor. Adrenalectomy was performed in 10 patients (33%) without biochemical testing for pheochromocytoma. Clinical parameters were similar among patients with metastasis, adenoma, or pheochromocytoma. There were no clinical predictors to suggest pheochromocytoma.ConclusionsPheochromocytoma occurs frequently in patients suspected of harboring adrenal metastasis, but this tumor is often not considered in clinical practice. The size and imaging characteristics of the adrenal mass and history of known metastasis may help clinicians in decision-making. Biochemical testing for pheochromocytoma should ideally be performed in all patients suspected of having adrenal metastasis. (Endocr Pract. 2008;14:967-972)     

Is 3-Tesla Gd-EOB-DTPA-Enhanced MRI with Diffusion-Weighted Imaging Superior to 64-Slice Contrast-Enhanced CT for the Diagnosis of Hepatocellular Carcinoma?

Objectives

To compare 64-slice contrast-enhanced computed tomography (CT) with 3-Tesla magnetic resonance imaging (MRI) using Gd-EOB-DTPA for the diagnosis of hepatocellular carcinoma (HCC) and evaluate the utility of diffusion-weighted imaging (DWI) in this setting.

Methods

3-phase-liver-CT was performed in fifty patients (42 male, 8 female) with suspected or proven HCC. The patients were subjected to a 3-Tesla-MRI-examination with Gd-EOB-DTPA and diffusion weighted imaging (DWI) at b-values of 0, 50 and 400 s/mm². The apparent diffusion coefficient (ADC)-value was determined for each lesion detected in DWI. The histopathological report after resection or biopsy of a lesion served as the gold standard, and a surrogate of follow-up or complementary imaging techniques in combination with clinical and paraclinical parameters was used in unresected lesions. Diagnostic accuracy, sensitivity, specificity, and positive and negative predictive values were evaluated for each technique.

Results

MRI detected slightly more lesions that were considered suspicious for HCC per patient compared to CT (2.7 versus 2.3, respectively). ADC-measurements in HCC showed notably heterogeneous values with a median of 1.2±0.5×10⁻³ mm²/s (range from 0.07±0.1 to 3.0±0.1×10⁻³ mm²/s). MRI showed similar diagnostic accuracy, sensitivity, and positive and negative predictive values compared to CT (AUC 0.837, sensitivity 92%, PPV 80% and NPV 90% for MRI vs. AUC 0.798, sensitivity 85%, PPV 79% and NPV 82% for CT; not significant). Specificity was 75% for both techniques.

Conclusions

Our study did not show a statistically significant difference in detection in detection of HCC between MRI and CT. Gd-EOB-DTPA-enhanced MRI tended to detect more lesions per patient compared to contrast-enhanced CT; therefore, we would recommend this modality as the first-choice imaging method for the detection of HCC and therapeutic decisions. However, contrast-enhanced CT was not inferior in our study, so that it can be a useful image modality for follow-up examinations.     

Computed tomography imaging of primary lung cancer in mice using a liposomal-iodinated contrast agent

Purpose

To investigate the utility of a liposomal-iodinated nanoparticle contrast agent and computed tomography (CT) imaging for characterization of primary nodules in genetically engineered mouse models of non-small cell lung cancer.

Methods

Primary lung cancers with mutations in K-ras alone (Kras^LA1) or in combination with p53 (LSL-Kras^G12D;p53^FL/FL) were generated. A liposomal-iodine contrast agent containing 120 mg Iodine/mL was administered systemically at a dose of 16 µl/gm body weight. Longitudinal micro-CT imaging with cardio-respiratory gating was performed pre-contrast and at 0 hr, day 3, and day 7 post-contrast administration. CT-derived nodule sizes were used to assess tumor growth. Signal attenuation was measured in individual nodules to study dynamic enhancement of lung nodules.

Results

A good correlation was seen between volume and diameter-based assessment of nodules (R²>0.8) for both lung cancer models. The LSL-Kras^G12D;p53^FL/FL model showed rapid growth as demonstrated by systemically higher volume changes compared to the lung nodules in Kras^LA1 mice (p<0.05). Early phase imaging using the nanoparticle contrast agent enabled visualization of nodule blood supply. Delayed-phase imaging demonstrated significant differential signal enhancement in the lung nodules of LSL-Kras^G12D;p53^FL/FL mice compared to nodules in Kras^LA1 mice (p<0.05) indicating higher uptake and accumulation of the nanoparticle contrast agent in rapidly growing nodules.

Conclusions

The nanoparticle iodinated contrast agent enabled visualization of blood supply to the nodules during the early-phase imaging. Delayed-phase imaging enabled characterization of slow growing and rapidly growing nodules based on signal enhancement. The use of this agent could facilitate early detection and diagnosis of pulmonary lesions as well as have implications on treatment response and monitoring.