CT screening for lung cancer Assessing a regimen's diagnostic performance

PURPOSE: The purpose of this study was to characterize the diagnostic performance of a regimen of CT screening for lung cancer. METHODS: Using a common protocol/regimen of screening, 2968 asymptomatic persons at high risk for lung cancer were enrolled in two studies [Early Lung Cancer Action Projects (ELCAP) I and II] for baseline and annual repeat screening. A total of 4538 annual repeat screenings were performed. The regimen's diagnostic performance was characterized in terms of frequency of positive result of the initial CT as well as of screen-diagnosis and Stage I screen-diagnosis among all diagnoses (interim-diagnoses included), all separately for baseline and annual repeat screenings. RESULTS: The proportions with positive result of the initial CT were 12% and 6% in the baseline and repeat screenings, respectively. The proportions of screen-diagnoses among all diagnoses (interim-diagnoses included) were 97% and 99% in the baseline and repeat cycles, respectively. The corresponding proportions of pre-surgical Stage I screen-diagnoses were 95% and 93%. CONCLUSION: The performance of the ELCAP regimen is quite satisfactory in avoiding over many positive results of the initial CT, and it produces highly promising diagnostic results as for the attainment of cure by early intervention.     

Thoracic wall involvement by Hodgkin disease and non-Hodgkin lymphoma: CT evaluation

Thoracic computed tomographic (CT) scans of 250 patients with newly diagnosed or recurrent lymphoma revealed thoracic wall involvement in 24 patients (11 with Hodgkin disease, 13 with non-Hodgkin lymphoma). Thoracic wall involvement occurred without contiguous mediastinal or parenchymal involvement in 17 patients. Of these, 13 patients had masses beneath the pectoralis muscles or within the breast, and four had masses arising from the ribs. Five additional patients had mediastinal masses with thymic involvement and parasternal extension through the thoracic wall. Pulmonary parenchymal lymphoma with thoracic wall invasion was noted in the remaining two patients. In five of nine patients receiving radiation therapy, treatment plans were modified by CT demonstration of thoracic wall lymphoma.     

纵隔低密度肿块病变的CT诊断

目的：提高纵隔低密度肿块病变的CT诊断水平。方法：回顾性分析52例经临床、手术及病理确诊的纵隔低密度肿块病例资料。结果：52例中皮样囊肿4例，畸胎瘤6例，胸腺囊肿3例，支气管囊肿5例，心包囊肿4例，脂肪瘤1例，胸内甲状腺肿囊变4例，胸腺瘤囊变5例，淋巴结肿囊变7例(淋巴瘤2例，淋巴结结核5例)，神经源性肿瘤囊变4例(神经节细胞瘤1例，神经鞘瘤2例，恶性神经纤维瘤1例)，纵隔血肿2例，纵隔脓肿6例。CT诊断正功率92．3％(48／52)。结论：纵隔低密度病变种类较多。CT检查可清楚显示病变的部位与特点，结合临床表现一般能作出准确的术前诊断。     

CT screening for lung cancer: suspiciousness of nodules according to size on baseline scans

PURPOSE: To assess the frequency with which a particular, possibly optimal work-up of noncalcified nodules less than 5.0 mm in diameter identified on initial computed tomographic (CT) images at baseline screening leads to a diagnosis of malignancy prior to first annual repeat screening, compared with a possibly optimal work-up of larger nodules. MATERIALS AND METHODS: Two series of baseline CT screenings in high-risk people were retrospectively reviewed. The first series (n = 1,000) was performed in 1993-1998; the second (n = 1,897), in 1999-2002. In each series, cases in which the largest noncalcified nodule detected was less than 5.0 mm in diameter and those in which it was 5.0-9 mm were reviewed to determine whether diagnostic work-up prior to first annual repeat screening showed or would have shown nodule growth and led or would have led to a diagnosis based on biopsy or surgical specimens. RESULTS: The frequency with which malignancy was or could have been diagnosed when the largest noncalcified nodule was less than 5.0 mm in diameter was 0 of 378, whereas when the largest noncalcified nodule was 5.0-9 mm in diameter, the frequency was 13 or 14 of 238. If persons with only nodules smaller than 5.0 mm had merely been referred for first annual repeat screening without immediate further work-up, the referrals for such work-up would have been reduced by 54% (from 817 [28%] to 385 [13%] of 2,897). CONCLUSION: In modern CT screening for lung cancer at baseline, detected noncalcified nodules smaller than 5.0 mm in diameter do not justify immediate work-up but only annual repeat screening to determine whether interim growth has occurred.     

Computed tomography and magnetic resonance imaging of mediastinal tumors

We describe the clinical, pathological, and imaging findings of mediastinal tumors with focus on thymic hyperplasia, thymic epithelial tumors, and germ cell tumors, malignant lymphoma, and various cystic masses. Chemical shift magnetic resonance imaging (MRI) is useful in characterization of the normal thymus and differentiation of hyperplastic thymus and thymic tumors. In contrast to noninvasive thymomas, invasive thymomas and thymic carcinomas show a more aggressive growth pattern. Local invasion and pleural spread are characteristic of invasive thymoma and mediastinal lymphadenopathy and distant metastasis suggest thymic carcinomas. Mature teratoma typically shows various computed tomography (CT) attenuation, and MR signal intensity depending on its contents and fat tissue and bone within the lesions are its characteristic findings. Seminomas typically have homogenous internal CT attenuation and MR signal intensity with minimal contrast enhancement. Nonseminomatous malignant germ cell tumors characteristically show prominent internal degenerative changes and invasion to the adjacent structures. In mediastinal lymphomas, a residual mass is common after treatment and MRI provides important information in distinguishing viable tumors from residual benign masses. Some mediastinal cysts may reveal high attenuation similar to solid lesions on CT depending on their contents and MRI can be useful in the differentiation of cystic masses from solid lesions.     

CT diagnosis of benign mediastinal abnormalities

Thoracic CT scanning was performed in 49 adult male patients to evaluate a suspected mediastinal mass. A correct diagnosis would have been made in only 20 instances on the basis of conventional chest radiography. Specific diagnoses established by CT included 14 cases of local or diffuse mediastinal fat deposition, five mediastinal cysts, and six anomalies or aneurysms of the great vessels. Four miscellaneous lesions were also clarified. Thoracic angiography would undoubtedly have diagnosed vascular abnormalities, but was obviated in most instances. CT accurately defined anatomic relationships and distinguished vascular from nonvascular masses in the 16 patients who underwent diagnostic thoracotomy or mediastinoscopy. When CT demonstrated a fatty or cystic lesion, no attempt at tissue confirmation was undertaken in all but two of the asymptomatic patients. Clinical follow-up from 6 months to 3 years in conjunction with select correlative radiologic procedures have supported the CT findings in the nonoperated group. CT should be the initial procedure for evaluating most patients with mediastinal abnormalities detected by plain chest radiography. If the patient is asymptomatic and the information provided by CT indicates a benign process, conservative management with careful follow-up is justified.     

CT screening for lung cancer: frequency and significance of part-solid and nonsolid nodules

OBJECTIVE: In the Early Lung Cancer Action Project (ELCAP), we found not only solid but also part-solid and nonsolid nodules in patients at both baseline and repeat CT screening for lung cancer. We report the frequency and significance of part-solid and nonsolid nodules in comparison with solid nodules. MATERIALS AND METHODS: We reviewed all instances of a positive finding in patients at baseline (from one to six noncalcified nodules) and annual repeat screenings (from one to six newly detected noncalcified nodules with interim growth) to classify each of the nodules as solid, part-solid, or nonsolid. We defined a solid nodule as a nodule that completely obscures the entire lung parenchyma within it. Part-solid nodules are those having sections that are solid in this sense, and nonsolid nodules are those with no solid parts. Chi-square statistics were used to test for differences in the malignancy rates. RESULTS: Among the 233 instances of positive results at baseline screening, 44 (19%) involved a part-solid or nonsolid largest nodule (16 part-solid and 28 nonsolid). Among these 44 cases of positive findings, malignancy was diagnosed in 15 (34%) as opposed to a 7% malignancy rate for solid nodules (p = 0.000001). The malignancy rate for part-solid nodules was 63% (10/16), and the rate for nonsolid nodules was 18% (5/28). Even after standardizing for nodule size, the malignancy rate was significantly higher for part-solid nodules than for either solid ones (p = 0.004) or nonsolid ones (p = 0.03). The malignancy type in the part-solid or nonsolid nodules was predominantly bronchioloalveolar carcinoma or adenocarcinoma with bronchioloalveolar features, contrasting with other subtypes of adenocarcinoma found in the solid nodules (p = 0.0001). At annual repeat screenings, only 30 instances of positive test results have been obtained; seven of these involved part-solid or nonsolid nodules. CONCLUSION: In CT screening for lung cancer, the detected nodule commonly is either only part-solid or nonsolid, but such a nodule is more likely to be malignant than a solid one, even when nodule size is taken into account.     

Diagnostic imaging of mediastinal masses in children.

Mediastinal masses are the most common thoracic masses in children. The encyclopedic list of diagnostic considerations can be distilled into a concise and practical differential diagnosis based on the location of the mass and the established prevalence of various tumors and pseudotumors in the mediastinal compartments. Malignant lymphoma, benign thymic enlargement, teratomas, foregut cysts, and neurogenic tumors make up 80% of mediastinal masses in children. Continuing advances in imaging technology have altered traditional approaches to the evaluation and diagnosis of mediastinal masses in children. Plain chest radiography remains the basic imaging examination to define location and morphology. Cross-sectional imaging subsequently clarifies the morphology and extent of the mass. In general, CT is the primary cross-sectional imaging procedure in the evaluation of most mediastinal masses in children. Exceptions to this rule include MR in children with posterior mediastinal masses or suspected vascular lesions: in such cases, MR imaging is the preferred initial postradiographic examination. Sonographic examination may be diagnostic in foregut cysts and some other mediastinal masses. Gallium-67 scintigraphy has an emerging role in management of malignant lymphoma.     

Indeterminate mediastinal invasion in bronchogenic carcinoma: CT evaluation

The computed tomographic (CT) scans of 80 patients with bronchogenic carcinoma classified as indeterminate for direct mediastinal invasion were retrospectively reviewed after the patients had undergone thoracotomy. Forty-eight (60%) of the masses were resectable, without invasion of the mediastinum, 18 (22%) focally invaded the mediastinum but were technically resectable, and 14 (18%) invaded the mediastinum and were not technically resectable. Although in most circumstances in this relatively small subset of patients CT was not helpful in differentiating masses with and without mediastinal invasion, CT was able to separate a large group of masses that were likely to be technically resectable. Thirty-six (97%) of 37 masses with one or more of these CT findings were considered technically resectable: contact of 3 cm or less with mediastinum, less than 90 degrees of contact with aorta, and mediastinal fat between mass and mediastinal structures. Of these 36 masses, 28 were resectable without mediastinal invasion, and eight were resectable with focal limited mediastinal invasion.     

纵隔囊性病变的CT诊断及鉴别诊断

目的探讨纵隔囊性病变的CT诊断及鉴别诊断.方法本组共12例,均经手术及病理证实,男9例,女3例,年龄17～55岁.12例均行CT平扫,其中5例行CT增强扫描.回顾性分析其CT表现.结果纵隔囊性病变中,胸腺囊肿3例,淋巴管瘤2例,支气管囊肿7例.3例胸腺囊肿中,2例位于前纵隔,1例位于左颈及前纵隔;2例淋巴管瘤,1例位于中纵隔,1例位于左颈及前、中纵隔.7例支气管囊肿,均位于中纵隔气管及支气管右旁区域.结论CT平扫结合增强扫描,不仅准确显示纵隔囊性病变的位置和形态,而且清楚显示其与邻近结构的关系,因此结合临床资料及发病部位,对于纵隔囊性病变一般能够达到术前定性诊断.     

Anterior mediastinal mass in children following chemotherapy for malignant disease: thymic hyperplasia vs recurrence

Anterior mediastinal masses in children following chemotherapy for malignant disease often cause diagnostic problems. Differential diagnosis of thymic hyperplasia from recurrence frequently poses a challenge both for the radiologist and the physician. Thymic hyperplasia was seen in five patients, three with Hodgkin's disease, one with Burkitt's lymphoma and one with Wilms' tumour, after chemotherapy. In one patient, thymic hyperplasia was proven by biopsy and the other four were followed. None of the masses in the anterior mediastinum showed difference in size or shape during follow-up. We recommend that such patients should be evaluated cautiously before planning an invasive procedure. In patients who did not have an anterior mediastinal mass prior to chemotherapy, diagnosis of thymic hyperplasia should be stressed.     

Lung cancer screening: simulations of effects of imperfect detection on temporal dynamics

PURPOSE: To use a mathematic model to demonstrate effects of imperfect detection on temporal dynamics of radiologic lung cancer screening. MATERIALS AND METHODS: Monte Carlo simulations of lung cancer screening programs were performed in subjects at high risk for developing cancer. The effects of detection probabilities, symptomatic presentation of tumors, tumor volume doubling time, and time between screenings were examined. Computed tomography (CT) and chest radiography models were used. RESULTS: For imperfect detection probabilities, the percentage of subjects with cancers detected with repeated screenings decreased to a steady-state value. The transition period was the period during which screenings were performed and detection rates decreased. At steady-state repeat screening, the proportion of subjects with cancers diagnosed at screening or by means of symptomatic presentation was determined by the annual probability of developing cancer and not by the sensitivity of the screening modality. The sensitivity of the screening technique did affect detected cancer size, number of interval cancers, and total number of cancers observed. CT was used to detect more total cancers over the course of the screening program and cancers with a smaller average size; moreover, fewer interval cancers were observed with CT screening than with chest radiography screening. CONCLUSION: Lung cancer screening with imperfect detection has a transition period between baseline screening and steady-state behavior of annual screenings. Advantages of CT screening include a decrease in the average cancer size at detection, a decrease in the number of observed interval cancers, and an increase in the total number of cancers observed. Steady-state behavior indicates that long-term trials of screening may not be necessary.     

纵隔囊性病变的CT与MRI诊断

目的：探讨纵隔囊性病变的CT、MRI诊断及鉴别诊断。方法：回顾性总结30例经手术、病理确诊的纵隔囊性病变的CT及MRI表现，包括胸腺囊肿7例，囊性畸胎瘤8例，气管、支气管囊肿9例，食管囊肿4例，囊性淋巴管瘤2例。结果：不同纵隔囊性病变均有其较特定的发病部位。7例胸腺囊肿中6例位于前上纵隔的胸腺区，1例位于前纵隔中下部；8例囊性畸胎瘤主要位于前纵隔中部、大血管起始处；9例气管、支气管囊肿位于中上纵隔，气管、支气管右旁区；4例食管囊肿，其中3例位于后纵隔，1例位于中纵隔；2例囊性淋巴管瘤，其中1例为颈纵隔型，1例为颈一腋纵隔型。结论：纵隔囊性病变虽无明显特征性影像学表现，仔细观察CT与MRI征象特点，结合发病部位，对提高本病的诊断具有重要意义。     

胸腺瘤的CT诊断

目的评估CT诊断良恶性胸腺瘤的价值.材料和方法分析31例经外科和病理证实的胸腺瘤的CT表现.结果良性胸腺瘤10例,除1例与左肺动脉局部有粘连外,其余边界均清晰.侵袭性胸腺瘤12例,胸腺癌9例,除1例鳞癌外,CT均为不规则肿块,血管间隙均受侵,前者心包受侵8例,胸膜受侵7例,后者心包受侵5例,胸膜受侵5例,肺转移4例,双肾上腺转移1例,胸骨破坏1例.结论CT能准确鉴别良性恶性胸腺瘤,显示恶性胸腺瘤的浸润范围,并对侵袭性胸腺瘤和胸腺癌进行鉴别.     

Pictorial Review of Mediastinal Masses with an Emphasis on Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) has become a crucial tool for evaluating mediastinal masses considering that several lesions that appear indeterminate on computed tomography and radiography can be differentiated on MRI. Using a three-compartment model to localize the mass and employing a basic knowledge of MRI, radiologists can easily diagnose mediastinal masses. Here, we review the use of MRI in evaluating mediastinal masses and present the images of various mediastinal masses categorized using the International Thymic Malignancy Interest Group''s three-compartment classification system. These masses include thymic hyperplasia, thymic cyst, pericardial cyst, thymoma, mediastinal hemangioma, lymphoma, mature teratoma, bronchogenic cyst, esophageal duplication cyst, mediastinal thyroid carcinoma originating from ectopic thyroid tissue, mediastinal liposarcoma, mediastinal pancreatic pseudocyst, neurogenic tumor, meningocele, and plasmacytoma.     

胸腺原发神经内分泌肿瘤的CT诊断与鉴别诊断

目的探讨胸腺原发神经内分泌肿瘤的CT特点。方法选取经组织病理学及免疫组化确诊的13例胸腺原发神经内分泌肿瘤病例的临床及影像学资料。结果13例中男性10例,女性3例。5例不典型类癌,1例典型类癌,2例小细胞神经内分泌癌,5例神经内分泌癌未明确分型;1例伴双侧肾上腺皮质增生改变;胸腺神经内分泌肿瘤通常表现为较大肿块影(4.6~12.8 cm),形态多不规则(n=7),多数无包膜境界不清(n=8),密度多不均匀、肿瘤内坏死囊变明显(n=10),少见钙化(n=1),未见明显出血或分隔,增强后不均匀轻中度强化,3例伴胸腔及心包积液,侵犯纵隔内脂肪或心脏大血管(n=12),4例合并纵隔淋巴结肿大,3例合并远处转移。结论胸腺神经内分泌肿瘤多表现为大肿块,形态不规则,密度不均匀,不均匀强化和局部侵犯,坏死囊变常见,若合并库欣综合征多能明确诊断,CT检查有助于疾病分期,指导治疗决策。     

Low dose CT in early lung cancer diagnosis: Prevalence data

PURPOSE: Lung cancer has a high mortality rate and its prognosis largely depends on early detection. We report the prevalence data of the study on early detection of lung cancer with low-dose spiral CT underway at our hospital. MATERIALS AND METHODS: Since the beginning of 2001, 519 asymptomatic volunteers have undergone annual blood tests, sputum tests, urinalyses and low-dose spiral CT. The inclusion criteria were age (=/> 55 years old), a history of cigarette smoking and a negative history for previous neoplastic disease. The diagnostic workup varied depending on the size and CT features of the nodules detected. RESULTS: At baseline, the CT scan detected nodules > 5 mm in 22% of subjects; the nodules were single in 42 and multiple in 71. In 53% of cases the findings were completely negative, while in 122 (23.4%) nodules with a diameter < 5 mm were detected. Six cases of lung cancer were identified, of which four were stage I, one stage was IIIB and one was stage IV with adrenal metastases. CONCLUSIONS: Our preliminary data on spiral CT as a potential new diagnostic tool for lung cancer screening, although less promising than the Japanese and ELCAP results, confirm the feasibility of the technique. Additional validation is, however, required.     

The anterior mediastinum: diseases

Mediastinal tumours are frequently asymptomatic and first noted on routine chest radiograph. In most cases, evaluation should proceed to spiral computed tomography (sCT) of the chest with iodinated contrast material. The specific location and appearance of tumours on sCT is instrumental in planning further diagnostic and treatment strategies. Primary tumours in the anterior mediastinum account for half of all mediastinal masses. They comprise various benign and malignant neoplasms, but a wide variety of nonneoplastic lesions (developmental, inflammatory) can present as a localised mass in this compartment. The most common primary anterior mediastinal tumours are thymoma, teratoma and lymphoma; all other lesions are rare. Nonneoplastic conditions include thymic cysts, lymphangioma and intrathoracic goitre. Understanding the pathology, clinical presentation, imaging and diagnosis of the major tumour types is instrumental in the safe and efficient work-up of a mediastinal mass. Patients with primary mediastinal masses and cysts will usually undergo surgical resection; radiological and clinical features should prompt limited biopsy specimens followed by oncologic consultation, and chemotherapy or radiotherapy when appropriate. The objective of this review was to examine the role of diagnostic imaging in the management of masses of the anterior mediastinum.     

Intrathoracic manifestations of metastatic testicular seminoma: a comparison of chest radiographic and CT findings

The chest radiographs and CT scans of 200 patients with pure testicular seminoma were reviewed. The radiographs showed evidence of intrathoracic metastatic disease in 25 patients (12.5%). Of these, 17 had an abnormal mediastinal contour, seven had pulmonary metastases, five had pleural effusions, and two had discrete pleural masses. CT showed evidence of intrathoracic metastatic disease in 30 patients (15%). This included mediastinal nodal enlargement in 21, pulmonary metastases in 12, pleural effusions in six, and pleural masses in two. CT not only showed disease in five patients with normal chest radiographs, but also showed additional sites of disease in four other patients with abnormal chest radiographs. The results suggest that mediastinal nodal enlargement is the most common intrathoracic manifestation of metastatic testicular seminoma. CT is more accurate than chest radiography in the detection of metastatic seminoma in the chest and defines the extent of metastatic disease more precisely.     

Tuberose sclerosis complex: analysis of growth rates aids differentiation of renal cell carcinoma from atypical or minimal-fat-containing angiomyolipoma

AIM: To study the radiological characteristics of renal masses in individuals with tuberous sclerosis complex (TSC) using serial CT, and to examine how renal cell carcinoma (RCC) may be differentiated from indeterminate cysts or masses. METHODS: This was a retrospective study of 12 cases of TSC in which dedicated renal CT followed after US had demonstrated cystic or sonographically unusual renal masses. The CT density of all masses was measured and the masses categorized as simple cysts, complex cysts, angiomyolipomas or indeterminate solid masses. Subjects were maintained on regular follow-up with repeat CT or MRI and interval renal US. Indeterminate masses that showed rapid growth were considered suspicious for renal cell carcinoma and biopsy or nephrectomy followed. RESULTS: Comparative data were available for a median of 4 years. In each case the renal masses were multiple and bilateral; mean mass diameter was 3.6 cm. Among a total of 206 masses, 18 were simple cysts and 3 were complex cysts. Of the complex cysts, 1 proved to be an angiomyolipoma on histology and the other 2 showed no growth. Of the solid masses, 133 were typical angiomyolipomas (AMLs) and 52 were indeterminate. On follow-up, only 3 indeterminate masses showed rapid growth (>0.5 cm/year), of which only 1 proved to be an RCC on biopsy. The other 2 were minimal-fat AMLs, and the remainder of the masses showed no or slow growth. CONCLUSION: Many renal masses associated with TSC are radiologically indeterminate. A growth threshold of >0.5 cm/year identified the only RCC in this study (0.5% of all masses). Yearly radiological follow-up of indeterminate renal masses is recommended for individuals with TSC.