Assessment of cystic renal masses based on Bosniak classification: comparison of CT and contrast-enhanced US

OBJECTIVES: To compare retrospectively the imaging features of computed tomography (CT) and contrast-enhanced US (CEUS) imaging for the assessment of cystic renal masses using the Bosniak classification system. MATERIALS AND METHODS: The CT and CEUS images of 31 pathologically confirmed cystic renal masses in 31 patients were retrospectively analyzed for septa numbers, wall and/or septa thickness, enhancement degree, and for the presence of a solid component by consensus between two radiologists using the Bosniak classification. Diagnostic accuracies of CT and CEUS for malignant cystic tumor were calculated and compared using McNemar test. RESULTS: Diagnostic accuracies of CT and CEUS for malignant renal tumor were 74% and 90%, respectively, but there were not statistically different (P>0.05). CEUS and CT images showed same Bosniak classification in 23 (74%) lesions and there were differences in 8 (26%) lesions, all of which were upgraded by CEUS; one lesion from I to IV, two lesions from II to IV, two lesions from IIF to III, and three lesions from III to IV. CEUS images depicted more septa in 10 (32%) lesions, more thickened wall and/or septa in 4 (13%) lesions, and stronger enhancement in 19 (61%) lesions. Moreover, for six lesions, solid component was detected by CEUS but not by CT. CONCLUSION: CEUS might better visualize septa number, septa and/or wall thickness, solid component and the enhancement of some renal cystic masses than CT, resulting in upgrade of Bosniak classification and affecting their treatment plan.     

Complex cystic renal masses: characterization with contrast-enhanced US

PURPOSE: To prospectively compare contrast material-enhanced ultrasonography (US) with computed tomography (CT) in the classification of complex cystic renal masses with the Bosniak system. MATERIALS AND METHODS: Ethics committee approval and written informed consent were obtained. Forty patients (17 women, 23 men; age range, 31-77 years) with 44 complex cystic renal masses detected with conventional US were prospectively examined by using second-harmonic US with a second-generation contrast agent and multiphasic helical CT. Thirty-six patients had one lesion, and four patients had two lesions. Surgical resection in nine patients and imaging follow-up in 31 patients were used to determine the outcome. RESULTS: On contrast-enhanced US images, masses were classified as Bosniak category II (n = 18), IIF (ie, lesions were classified as category II and follow-up was needed) (n = 16), III (n = 7), or IV (n = 3) lesions. On CT images, masses were classified as Bosniak category II (n = 24), IIF (n = 10), III (n = 7), or IV (n = 3) lesions. Interobserver agreement was high (kappa = 0.86, P < .001) for classification with US. Complete concordance between the readers was found for classification with CT. Complete concordance between contrast-enhanced US and CT was observed in the differentiation of surgical and nonsurgical complex cysts. Complete concordance among the three readers in the assessment of vascularity with contrast-enhanced US was found. Interobserver agreement in the evaluation of enhancement on CT images was high (kappa = 0.88, P < .001). Concordance between contrast-enhanced US and CT in the evaluation of vascularization was high (kappa = 0.77, P < .001). CONCLUSION: The study data suggest that contrast-enhanced second-harmonic US is appropriate for renal cyst classification with the Bosniak system.     

Cystic renal masses: usefulness of the Bosniak classification

To determine the usefulness of the Bosniak classification of cystic renal masses, the computed tomographic (CT) and ultrasound findings of 16 pathologically proven cystic renal masses were retrospectively reviewed. All imaging studies were reviewed and categorized utilizing the Bosniak classification without knowledge of the final pathologic diagnosis. There were no category I lesions (classical simple cyst), four category II (minimally complicated), seven category III lesions (more complicated), and five category IV lesions (probable malignant). All category II lesions were benign, all category IV lesions were malignant. Of the seven category III lesions, three were benign and four were malignant. We conclude that the Bosniak classification is extremely useful in the management of cystic renal masses.     

Follow-up CT of moderately complex cystic lesions of the kidney (Bosniak category IIF)

OBJECTIVE: The purpose of this study is to show the use of follow-up CT studies in the management of moderately complex cystic lesions of the kidney (Bosniak category IIF). MATERIALS AND METHODS: The CT scans of 42 moderately complex cystic renal masses (Bosniak category IIF) with follow-up examinations for 2 years or greater or with pathology correlation (n = 3) were retrospectively analyzed by the authors in consensus. The complexity of each lesion was assessed on the basis of the number and appearance of the septa, wall thickness, interface with the kidney parenchyma, presence and amount of calcification, and contrast enhancement characteristics. Lesion size was measured in two dimensions. Follow-up examinations were evaluated for any interval change. RESULTS: The average size of the lesions was 3.9 x 3.6 cm, and the average follow-up time was 5.8 years (range, 2 years-18 years 4 months; median, 5.0 years). Eighteen lesions had fewer than five septa, 16 lesions had between five and nine septa, and eight lesions had more than nine septa. In 39 lesions, the wall or septa or both were slightly thickened, and in a single lesion, the wall and septa were hairline thin. The two remaining lesions were of uniformly high attenuation and completely intrarenal. Forty-one lesions had a sharp interface with the kidney, whereas one had an indistinct interface. Twenty lesions contained calcium. Enhancement was not shown in any lesions except for minimal enhancement of smooth walls or septa of some lesions. Follow-up examinations showed that three lesions had developed more calcification, one lesion had increased in overall size but appeared less complex, and three lesions had decreased in size. In addition, two lesions had become more complex and developed thicker septa, and these lesions proved to be cystic neoplasms. CONCLUSION: Follow-up CT studies are an effective way of managing patients with moderately complex cystic lesions of the kidney (Bosniak category IIF) because the absence of change supports benignity and progression indicates neoplasm.     

Calcification in cystic renal masses: is it important in diagnosis?

PURPOSE: To determine whether the presence of calcifications in cystic renal masses is important in diagnosis and to suggest an approach to the management of calcified cystic renal masses. MATERIALS AND METHODS: Eighty-one cystic renal masses containing calcification in a wall or septum were evaluated by means of review of computed tomographic (CT) images (n = 81), follow-up CT images (n = 28), and results of pathologic examination (n = 40) by the authors in consensus. Images were evaluated for lesion size, amount and morphology of calcification, and any association of calcification with soft-tissue structures. Lesions were categorized according to the Bosniak cyst classification system; the amount of calcification was determined with a subjective grading system. Progression of calcification was qualitatively determined with available follow-up CT scans. RESULTS: Twenty-one lesions were Bosniak category II (benign) and showed small amounts and thin strands of calcification. Nineteen lesions containing more extensive calcification but no enhancing tissue were category IIF. Follow-up CT results available for 16 of these lesions (average follow-up length, 5 years 8 months) showed no substantial change. The three remaining lesions were proved benign at surgery. Twenty-five lesions were category III; surgical intervention was performed in 21 of these (benign, n = 12; malignant, n = 9). Sixteen lesions that contained obvious areas of enhancing soft tissue were category IV and proved malignant at surgery. CONCLUSION: Calcification in a cystic renal mass is not as important in diagnosis as is the presence of associated enhancing soft-tissue elements. This information should enable a reasonable approach to the management of calcium-containing renal cystic lesions.     

Cystic renal masses: Usefulness of the bosniak classification

To determine the usefulness of the Bosniak classification of cystic renal masses, the computed tomographic (CT) and ultrasound findings of 16 pathologically proven cystic renal masses were retrospectively reviewed. All imaging studies were reviewed and categorized utilizing the Bosniak classification without knowledge of the final pathologic diagnosis. There were no category I lesions (classical simple cyst), four category II (minimally complicated), seven category III lesions (more complicated), and five category IV lesions (probable malignant). All category II lesions were benign, all category IV lesions were malignant. Of the seven category III lesions, three were benign and four were malignant. We conclude that the Bosniak classification is extremely useful in the management of cystic renal masses. The opinions expressed herein are those of the authors and are not to be construed as official or as reflecting the views of the Uniformed Services University of the Health Sciences, the Department of Defense, or the United States Navy     

Cystic tumors of the kidney in adults: radio-histopathologic correlations

The purpose of this study is to provide an updated pathologic-radiologic classification of cystic renal tumors and to assess imaging diagnostic capabilities. Eighty seven cases of cystic renal tumors explored with multimodality imaging (ultrasonography, CT, MRI, arteriography) and with histopathologic correlation are reported. The most common cystic carcinomas were multilocular cystic renal cell carcinoma (33%) and the pseudocystic necrotic carcinoma (31%), which usually belong to category IV. Less common cystic carcinomas were unilocular cystic renal cell carcinoma (6%) and renal cyst wall carcinoma (6%). The association of thin septa and large locules are suggestive findings for multilocular cystic nephroma, but such criteria are not specific enough to recognize benign multilocular cystic nephroma and to exclude multilocular cystic renal cell carcinoma. Since carcinomatous degeneration may occur within the wall of such tumors, especially in von Hippel Lindau disease, surgery is still required. The results of our study corroborate the Bosniak classification of cystic renal masses: no tumors belonged to the category I or II, all cystic masses which belonged to the category IV were malignant tumors, category III included benign and malignant tumors.     

Differentialdiagnose fokaler Nierenläsionen in CT und MRT

The great majority of renal masses are found incidentally as a result of the use of ultrasonography, computed tomography (CT) and magnetic resonance imaging (MRI). If ultrasonography is not diagnostic CT or MRI should be initiated to differentiate lesions of the kidney that need surgical intervention from those that do not and from those that need follow-up examinations.Cystic renal masses are characterized by using the Bosniak classification, including category IIF. In solid lesions of the kidney first non-surgical lesions as well as lymphoma, renal infarction and nephritis should be excluded. Identifying fatty components in renal lesions is very important because in angiomyolipoma they are almost always present.CT and MRI are exellent for tumor detection. Careful evaluation of imaging finding combined with the patient′s history should assist the radiologist in making the proper diagnosis or recommending the appropriate treatment in most cases.This article provides a review about renal masses, the imaging methods for their evaluation and their characteristic features at CT and MR imaging. Different lesions are demonstrated like xantogranulomatous pyelonephritis, acute pyelonephritis, renal infarction, lymphoma, angiomyolipoma, renal oncocytoma, cystic lesion and polycystic disease the kidney, echinococcosis, renal cystadenoma, metastases, renal cell carcinoma (RCC), and multiple bilateral RCC in patients with Hippel-Lindau-Syndrome.This article should help to differentiate complex cystic lesions of the kidney by using the Bosniak-classification, especially Bosniak Category IIF. Solid masses should be characterized and the major question to be answered is whether the mass represents a surgical or nonsurgical lesion or if follow-up studies are necessary.     

CT与MRI下Bosniak分级对肾脏囊性病变诊断性能的对比研究

目的 比较CT下Bosniak分级和MRI下Bosniak分级对肾脏囊性病变的诊断性能.方法 回顾性分析30例(共42个肾脏囊性病灶)同时具备CT和MRI影像资料,并以术后病理或临床随访作为最终诊断,采用ROC曲线比较二种检查模式的诊断性能.结果 CT下Bosniak分级Ⅰ～Ⅳ级分别为6个、24个、9个、3个,对照病理结果其假阳性病灶数0个,假阴性病灶数14个.MRI下Bosniak分级Ⅰ～Ⅳ级分别8个、18个、10个、6个,对照病理结果其假阳性病灶数0个,假阴性病灶数11个.MRI下Bosniak分级的曲线下面积大于CT下Bosniak分级,前者的特异度和敏感度均高于后者.结论 MRI下Bosniak分级对于肾脏囊性病变的诊断性能高于CT下Bosniak分级,在条件允许的情况下应首先采用MRI下Bosniak分级.     

Current status of imaging indeterminate renal masses

In 1986 Bosniak proposed a classification of cysts and cystic renal masses in an attempt to define precisely the radiologic findings for lesions not requiring further evaluation and for those that should be explored surgically in an attempt to salvage normal renal parenchyma. This classification has been extremely useful in expanding the number of patients treated conservatively. The following entities can be considered benign and require no further evaluation: the classic simple cyst (Bosniak category 1), a cyst with benign calcification (see Fig. 1A and B), a hyperdense cyst (see Fig. 2), and a cyst with thin (less than or equal to 1mm) septations (see Fig. 5A; Bosniak category 2). When any of the following features are present, further evaluation is warranted: aggressive calcifications (see Fig. 1C-E), abnormal density not fulfilling the criteria of a hyperdense cyst (see Figs. 3 and 4), or nodular septations (see Fig. 5B and C), or wall thickening (see Fig. 7; Bosniak) category 3). Small masses that cannot be characterized accurately also require further evaluation. Multiloculated masses(see Fig. 9) require surgery (Bosniak category 3). Most cases of multiple localized renal cysts can be distinguished from multiloculated masses and do not require surgery (see Fig. 10). Evaluation of cyst fluid by MR imaging has not been proved reliable in differentiating benign and malignant masses. MR imaging will become more useful when its spatial resolution equals that of CT. Masses that remain indeterminate after careful evaluation by ultrasonography and CT scanning can be evaluated additionally by angiography or cyst puncture. Management options for persistent enigmatic masses include follow-up radiologic studies, exploration, local excision, and nephrectomy.     

Assessment of cystic renal masses in children: Comparison of multislice computed tomography and ultrasound imaging using the Bosniak classification system

To retrospectively compare contrast-enhanced multislice computed tomography (MSCT) and ultrasound (US) imaging for the assessment of cystic renal masses in children using the Bosniak classification system. Twenty-two consecutive patients (age 1 month to 5.2 years, mean 2.4 years) with 24 cystic renal masses (7 benign, 17 malignant) pathologically confirmed after surgical resection underwent both MSCT and US imaging, and were retrospectively analyzed using the Bosniak classification. A senior and a junior radiologist retrospectively and independently reviewed imaging findings. The sensitivity, specificity, positive predictive value and negative predictive values of MSCT and US were assessed using diagnostic statistics. The statistical significance of differences was determined by the McNemar test. Both radiologists accurately predicted lesions of categories I and IV with the Bosniak classification using MSCT and US. All masses classified as Bosniak classes I and II were proven to be benign, and all malignant lesions were correctly characterized in all cases both on ultrasound images and on the contrast-enhanced CT (CECT) images. Two benign multilocular cystic nephromas and one multicystic dysplastic kidney were classified into category III or even IV based on the classification scheme because of their multilocular nature and thick septation. The diagnostic accuracy of CECT was slightly better than ultrasound (CECT vs. US: senior reader, 92% vs. 88%; junior reader, 88% vs. 83%). However, there was no statistically significant difference between the two sets (p > 0.05). The two radiologists had perfect inter-observer agreement on the two modalities. Both MSCT and US provide highly accurate diagnosis for the malignant renal cystic masses in children using the Bosniak classification system, but assessment of benign masses still needs improvement. We would recommend US is the best screening modality in Bosniak I and II, In Bosniak III and IV, MSCT are first the choice.     

Incidence of malignancy in complex cystic renal masses (Bosniak category III): should imaging-guided biopsy precede surgery?

OBJECTIVE: Complex indeterminate renal cystic masses (Bosniak type III) can have benign and malignant causes and have been traditionally considered surgical lesions. We sought to determine the incidence of malignancy and to assess a possible role for imaging-guided biopsy for this category of renal masses. MATERIALS AND METHODS: Three hundred ninety-seven renal biopsies were performed at our institution between 1991 and 2000. Between January 1997 and August 2000, 28 Bosniak category III lesions, based on established CT imaging criteria on helical CT scans, were identified for analysis. The incidence of malignancy, based on surgical pathology or imaging follow-up and percentage of lesions proceeding to surgery, among these 28 lesions, was determined. The surgical results were correlated with the biopsy findings. RESULTS: Of the 28 biopsied category III lesions, 17 (60.7%) were malignant (16 renal cell carcinomas and one lymphoma), and 11 (39.3%) were benign (six hemorrhagic cysts, three inflammatory cysts, one metanephric adenoma, and one cystic oncocytoma). Seventeen of the 28 lesions (16 renal cell carcinomas and one inflammatory cyst) had surgical resection after the biopsy. All resected lesions had pathologic diagnoses identical to the percutaneous imaging-guided biopsy results. The remaining 11 patients who had undergone nonsurgical biopsies had radiologic follow-up for a minimum of 1 year, with benign lesions showing no interval change. CONCLUSION: Renal biopsy and radiologic follow-up were useful in identifying nonmalignant lesions in complex cystic renal masses and avoided unnecessary surgery in 39% of patients.     

Cystic renal masses: accurate Bosniak classification requires adequate renal CT

OBJECTIVE: The objective of this study was to assess the practical usefulness of the Bosniak classification system for separating surgical from nonsurgical cystic renal masses in a large number of patients examined with properly performed renal CT. The study included only patients whose scans were technically adequate to allow proper assignment of the lesion to a category. MATERIALS AND METHODS: The scans of 109 patients were gathered from two large teaching institutions both prospectively and retrospectively, yielding a total of 116 analyzable renal cystic lesions. Eighty-two masses were resected from 77 of these patients, retrospectively categorized by two experienced uroradiologists using the Bosniak classification system, and correlated with pathology reports. A second group of 34 lesions in 32 patients with atypical cysts was followed up prospectively for periods ranging from 3 months to 10 years. RESULTS: The results were similar for the two institutions: 15 resected categories I and II lesions were correctly identified as benign, and all 18 category IV lesions were malignant. Twenty-nine (59%) of 49 pooled category III masses were malignant. No malignancies have been identified in the prospectively monitored group of patients. CONCLUSION: Our results are compared with earlier, smaller series and support those that show that the Bosniak classification system is useful in separating lesions requiring surgery from those that can be safely followed up, provided proper CT techniques are used.     

肾脏囊性病变的MSCT表现及Bosniak分级在其中的应用

目的：讨论肾脏囊性病变的MSCT表现及Bosniak分级在肾脏囊性病变中的应用价值。方法：前瞻性分析我院肾脏囊性病变Mscr表现同时进行Bosniak分级,其中取得病理证实的有26例,将Bosniak分级结果与病理结果对照。结果：Bosniak Ⅰ级中2例都为良性,Ⅱ级4例都为良性,Ⅱ／F级3例,1例恶性（1／3）,Ⅲ级恶性3例（3／8）,Ⅳ级中9例都是恶性。结论：诊断肾脏囊性病变要注意影像特征,Bosniak分级对于诊断、指导治疗均有帮助,但Bosniak分级对于ⅡF级、Ⅲ级囊性病变存在不足之处。     

Complex renal cysts: findings on MR imaging.

OBJECTIVE: We retrospectively evaluated our experience with complex cystic renal masses on MR imaging, using T1-weighted, T2-weighted, and gadolinium-enhanced images, to determine whether imaging features could permit distinction between benign and malignant lesions. MATERIALS AND METHODS: Thirty-seven patients with complex cystic renal lesions were included in this retrospective study. The patients selected had undergone T1-weighted, T2-weighted, and gadolinium-enhanced MR imaging examinations using 1.5-T scanners, with at least one of the following findings: cyst fluid of heterogeneous signal intensity, mural irregularity, septa, mural masses or nodules, increased mural thickness, or intense mural enhancement. The diagnosis was established by histology in 19 patients and by follow-up studies in the remaining 18 patients. RESULTS: Fifty-five complex renal cystic lesions were present in the 37 patients. Among the 55 lesions, of 37 that contained fluid of a heterogeneous signal intensity, eight were malignant (22%); of 16 with irregular walls, 10 were malignant (63%); of four with septa, two were malignant (50%); of four with mural masses or nodules, three were malignant (75%); of 14 with a thick wall (>2 mm), 10 were malignant (71%); and of 32 with intense mural enhancement, 14 were malignant (44%). As independent variables, mural irregularity, mural masses or nodules, increased mural thickness, and intense mural enhancement each were highly associated with malignancy (p = .0003-.0022). The combination of mural irregularity and intense mural enhancement had the highest correlation with malignancy (p = .0002). CONCLUSION: The combination of mural irregularity and intense mural enhancement is a strong predictor of malignancy in renal cystic lesions. However, the appearance of benign and malignant lesions may overlap, suggesting that distinct separation of these entities is not currently possible in all cases with MR imaging.     

Bosniak分级在MRI诊断肾脏复杂囊性病变中的应用

目的：探讨Bosniak分级在MRI诊断肾脏复杂囊性病变中的应用.方法：41例经病理证实的肾脏复杂囊性病变,恶性28例,良性13例.观察其MRI表现,进行Bosniak分级.并与病理及手术结果进行对照.结果：恶性、良性两组分隔数量大于4的病变比例分别为67.9%和23.1%,差异有显著性意义（P=0.007）.恶性组中囊壁或分隔增厚的病变中88.2%可见不规则增厚,明显高于良性组的28.6%（P=0.009）.9例病变实性成分大于25%,6例有假包膜征象,病理证实均为恶性.恶性、良性组中病变有明显强化分别占85.7%扣23.1%,差异有显著性意义（P〈0.001）.强化征象诊断恶性的敏感度、特异度和符合率分别为82.6%、76.9%和82.9%.恶性组Ⅱ～Ⅳ级病变和Ⅱ～ⅡF级病变比例分别为89.3%和10.7%,良性组为30.8%和69.2%,差异有显著性意义（P〈0.001）.结论：增强仍是MRI Bosniak分级和良性鉴别的最可靠征象,囊壁和分隔的增厚、实性成分比、分隔数量及假包膜等征象也有重要诊断价值.     

超声造影结合Bosniak标准在良恶性肾囊性病变鉴别诊断中的价值

目的 评价超声造影鉴别良恶性肾囊性病变的准确性,探讨超声造影结合Bosniak标准分级诊断肾囊性病变的可行性.资料与方法 对30例患者的36个肾囊性病灶进行超声造影,分析良恶性肾囊性病变的超声造影征象;按照Bosniak标准对超声造影的表现进行分级诊断,计算其敏感性、特异性、诊断符合率、阳性预测值、阳性似然比、Kappa值及验后概率,分析该方法分级诊断肾囊性病变的准确性.结果 超声造影可显示常规超声不能发现的囊内分隔及实性结构.超声造影结合Bosniak标准诊断肾囊性病变的敏感性、特异性、诊断符合率、阳性预测值、阳性似然比分别为92.9％、90.9％、94.8％、86.7％、10.2,Kappa=0.83;应用超声造影结合Bosniak标准可提高肾囊性病变良恶性诊断的验后概率.结论 超声造影结合Bosniak标准可以提高鉴别诊断肾囊性病变良恶性的准确性.     

肾脏孤立性纤维瘤影像诊断

目的:探讨肾脏孤立性纤维瘤的病理及影像学表现,提高对少见肾脏肿瘤的诊断与鉴别诊断.方法:回顾手术病理证实的2例肾孤立性纤维瘤影像学和病理学表现.结果:2例肾肿瘤均起自肾实质并突入肾盂,大小分别为2cm和3cm;在CT平扫时均表现为略高密度软组织肿块,边缘清楚锐利,增强后有轻中度强化.其中1例行MRI检查,T2WI上肿块与肾实质比为明显低信号.病理学表现:境界清、质硬的肿块,切面灰白或黄白色有漩涡和编织状结构,形态类似子宫的平滑肌瘤.显微镜下孤立性纤维瘤可见成纤维细胞样细胞交错缠绕在一起伴大量的胶原纤维沉积,成蟹足样.免疫组织化学CD34强阳性.结论:肾孤立性纤维瘤罕见,其由于纤维组织致密造成CT上肿瘤密度较肾实质高,在MRI的T2WI上肿瘤为低信号表现,有助其诊断与鉴别诊断.     

Cystic neoplasms of the pancreas: comparison of MR imaging with CT

Cystic neoplasms of the pancreas are divided into two major groups: microcystic adenomas and mucinous cystic neoplasms. Five microcystic adenomas and seven mucinous cystic neoplasms (three cystadenomas and four cystadenocarcinomas) were examined with both magnetic resonance (MR) imaging and computed tomography (CT). The cystic content was differentiated more easily with MR imaging than with CT. It was homogeneous in four of the five microcystic adenomas, all of which had lobulated borders best seen on T2-weighted images. The mucinous cystadenomas and cystadenocarcinomas were all composed of multiple compartments that varied in signal intensity. The septa, shape, and wall thickness were demonstrated on T1- and/or T2-weighted MR images almost as well as on CT scans. Overall, MR imaging was equal or slightly superior to CT in the diagnosis of pancreatic cystic neoplasms, except in its limited ability to demonstrate calcifications of the tumor wall and septa.     

Detection of focal hepatic masses: prospective evaluation with CT, delayed CT, CT during arterial portography, and MR imaging

The sensitivities of contrast medium-enhanced computed tomography (CT), delayed CT (DCT), CT during arterial portography (CTAP), and magnetic resonance (MR) imaging for detecting focal liver lesions were prospectively evaluated in eight patients who subsequently underwent hepatic lobectomy or transplantation. Pathologic evaluation of the resected liver specimens demonstrated 37 lesions. The sensitivities were 81% (30 of 37 lesions) for CTAP, 57% (21 of 37 lesions) for MR imaging, 52% (12 of 23 lesions) for DCT, and 38% (14 of 37 lesions) for contrast-enhanced CT. The difference between the sensitivity of CTAP and the sensitivities of the other imaging tests was statistically significant (P less than .004). Of the lesions smaller than 1 cm in diameter, CTAP depicted 61% (11 of 18 lesions), MR imaging 17% (three of 18 lesions), CT 0% (zero of 18 lesions), and DCT 0% (zero of nine lesions). It is concluded that for preoperative detection of focal hepatic masses, CTAP is the most accurate technique available to most radiologists. Patients with primary or secondary hepatic neoplasms who are being considered for hepatic resection should undergo CTAP as part of their preoperative examination.