MR imaging in the assessment of lung cancer patients: primary lung cancer staging, evaluation of therapeutic effect and diagnosis of recurrent tumor

Magnetic resonance imaging and computed tomography were compared in a prospective study of 137 lung cancer patients proved by surgery or autopsy for determining the staging, evaluation of therapeutic effect and diagnosis of recurrent tumor. 1. Lung cancer staging In peripheral lung cancer, T1 and T2 relaxation times of the tumors before operation have some correlation with those of operated specimens. These relaxation times, however, are of limited nodule characterization. Hilar mass and adjacent pulmonary consolidation (obstructive pneumonia or collapse) can be distinguished on T2-weighted image (77%) and Gd-DTPA enhanced image (80%). Therefore these images help in distinguishing tumor from peripheral lung disease. In the diagnosis of tumor invasion to the heart and great vessels, MRI is superior to CT because MRI can be helpful in distinguishing true mass from heart and great vessels. As for the chest wall, MRI is more useful than CT in detecting tumor invasion especially to the thoracic inlet and superior regions. In the diagnosis of mediastinal and hilar lymphadenopathy, MRI is equivalent or slightly inferior to CT, but MRI can easily demonstrate the lymphadenopathy at subcarinal region on coronal image. 2. Evaluation of therapeutic effect in lung cancer patients treated by radiation and chemotherapy MRI patterns of therapeutic effect was divided into 3 types. It is suggested that there is some correlation between these patterns and histologic types. MRI can easily demonstrate necrotic area on T2-weighted and Gd-DTPA enhanced images. 3. Diagnosis of recurrent tumor in treated lung cancer Concerning detecting recurrent tumor after surgery or irradiation, and delineating tumor from radiation pneumonitis, T2-weighted and Gd-DTPA enhanced images are of clinical value.     

肺癌的影像学分期

肺癌的分期明确了病变的范围,正确的分期对决定能否手术、选择治疗方法和预测预后都十分重要。本文介绍了新修订的国际抗癌协会（UICC）1997年肺癌分期法,包括TNM分期和临床分期,影像学方法是用于患者分期中的最重要的无创伤性技术,胸部和上腹部CT是其中的标准检查方法。本文详细叙述了CT在肺癌分期中的价值及其不足之处,其中主要描述了邻近结构的肺癌侵犯和淋巴结转移的影像表现。MRI在诊断肺上沟癌和纵隔受累上较CT为优。PET有望在将来成为分期中的优良技术。     

Lung cancer staging: the role of computed tomography and magnetic resonance imaging

Because complete resection remains the only reliable method of cure of lung cancer, one important aim of preoperative staging is to select patients with localised disease who may benefit from surgery, while avoiding unnecessary thoracotomies in patients with unresectable neoplasm. Computed tomography (CT) of the chest is a valuable method for staging local and regional spread of lung neoplasms, although limitations in its accuracy are well-known. While gross invasion of the mediastinum and major structures as well as the presence of metastatic disease can be easily demonstrated with CT, differentiation between tumour contiguity and subtle invasion of mediastinum or chest wall often remains a problem. Although magnetic resonance imagaing (MRI) may have the same limitations as CT, in specific situations it may b superior in diagnosing minimal chest wall or mediastinal invasion. Moreover, MRI is useful in the assessment of patients with superior sulcus tumours as well as in patients with contraindication to intravenous administration of ionic contrast material. Since nodal size is the only useful criterion for evaluating lymph node metastases, CT and MRI show similar, poor accuracies in lymph node staging reesulting from both low sensitivity (normal-sized nodes may contain microscopic metastases) and low specificity (enlarged lymph nodes may be reactive). For this reason, if enlarged lymph nodes are detected, further evaluation is recommended before excluding the patient from a potentially curative resection. Advantages and limitations of CT and MRI in the preoperative staging of non-small-cell carcinoma are reviewed in this article. The imaging of small-cell carcinoma is not included because most patients with this cell type do not benefit from surgical resection. Similarly we do not discuss imaging of distant metastases.     

Staging of non-small cell bronchial carcinoma using CT and MRT

The TNM Classification was rewritten by UICC in 1987. For non-small-cell bronchogenic carcinoma, stages T4 and N3 were redefined. Controversy exists in the literature regarding the clinical merits of CT and MRI examinations for staging. For the evaluation of very small tumors and lung parenchyma CT is superior to MRI. MRI, however, permits direct imaging of sagittal and coronal projections. This is favorable in the diagnosis of "superior sulcus tumors" and tumors with chest wall invasion. For the evaluation of T4 tumors and mediastinal lymph-node involvement, no additional contrast medium is necessary if MRI is used. Up to now, the main limitations for the application of MRI in thoracic imaging have been and still are the availability of the equipment, the costs, the necessary technical support, and the extensive study time.     

The role of nuclear medicine in pulmonary neoplastic processes

It has been demonstrated that the single most important factor in determining survival in patients with bronchogenic carcinoma is the extent of spread of metastasis from the primary lesion. This explains the extensive efforts in developing accurate staging tests for pulmonary tumors, both primary and metastatic, with special emphasis on the determination of pulmonary hilar and mediastinal spread of disease. Continued improvements in nuclear medicine instrumentation along with the development of tumor specific radiopharmaceuticals, as well as agents that have the capability of tracking tumor viability, have changed the orientation of scintigraphic techniques in the evaluation of pulmonary neoplastic processes. Gallium scintigraphy is no longer considered as a primary imaging modality in the staging of pulmonary tumors, and in most institutions has been replaced by computed tomography (CT) for this purpose. It has been demonstrated that gallium, relative to other imaging modalities, is a sensitive indicator of hilar spread of tumor. However, because of the normally high background activity within the sternum and spine, mediastinal abnormalities are poorly detected. Since most pulmonary tumors metastasize via regional nodes to the pulmonary hilum and then to the mediastinum, the high sensitivity for the detection of pulmonary hilar abnormalities and the high specificity for mediastinal lesion detection suggest that gallium scintigraphy is a valuable adjunctive test when used appropriately. Thallium 201 as a tumor agent is being studied by several institutions. Preliminary results indicate a high degree of sensitivity for the detection of pulmonary hilar and mediastinal lesions and there are early indications that thallium is a promising agent to evaluate tumor viability. With the development of new generation monoclonal antibodies, the prospects for highly sensitive and specific agents for detecting hilar and mediastinal spread of tumor is extremely encouraging. CT and NMR have made major contributions to the noninvasive workup of patients with bronchogenic carcinoma. Neither modality has been demonstrated to be accurate enough to adequately evaluate this patient population. Thus, there is a critical need for new noninvasive tests that will accurately assess the status of the patient so that appropriate therapy can be instituted.     

Magnetic resonance imaging of the hila and mediastinum

In the diagnosis of chest diseases, MR imaging has been shown to be most helpful in the evaluation of hilar and mediastinal lesions. The detection of intrathoracic abnormalities is technique-dependent, and imaging with both short and long repetition and echo times is necessary. ECG gating and sagittal or coronal images supplement transaxial scans in some patients. MR allows the diagnosis of mediastinal vascular lesions and the differentiation of mediastinal mass and vessel without contrast agents. It provides diagnostic information quite similar to that of CT in patients with mediastinal mass, but spatial resolution is somewhat poorer. In patients with hilar mass, MR is superior to CT in identifying the mass and distinguishing it from normal structures.     

Staging intrathoracic non-small-cell lung cancer

This article outlines the ability of imaging techniques to stage intrathoracic non-small-cell lung cancer, particularly the extent of primary tumour (T stage), and the presence of nodal metastases (N stage). The detection of hilar and mediastinal lymph-node metastases by CT is covered initially, followed by an appraisal of MRI and radionuclide imaging techniques. Finally, the evaluation of mediastinal and chest-wall invasion by CT and MRI is described, and note is made of developing applications of ultrasound and endosonography. Computed tomography remains the standard technique, but its limitations are discussed, as is the value of other complementary imaging techniques. Received: 12 February 1996; Revision received 11 June 1996; Accepted 19 June 1996     

椎旁原始神经外胚层瘤CT和MRI诊断

目的:研究椎旁外周性原始神经外胚层瘤(pPNET)的CT及MR表现,提高对该病的认识。方法:报道5例经手术病理证实的pPNET的临床、CT、MRI及组织学所见,并复习相关文献。结果:5例均见单侧椎旁肿块,累及椎管内硬膜外,肋骨骨质侵蚀,胸髓受压变形;CT显示肿块形态不规则、密度均匀;MRI示T1WI肿块信号均匀、略高于邻近骨骼肌信号,T2WI呈不均匀高信号,增强后肿块明显均匀强化。术后MRI显示局部肿块复发和胸腔积液,CT发现肺部、纵隔多发转移结节。结论:pPNET为少见的起源于胸壁、椎旁的恶性肿瘤,其CT、MRI表现无特征性,但可明确肿瘤的范围、进行手术切除可能性评估及治疗后随访。CT易显示肋骨、椎体骨质破坏、肺部小转移灶,MRI则可显示胸壁受累、胸髓受压变形的程度和范围等。     

CT and MRT in mediastinal and hilar space-occupying lesions

Thirty-eight patients with mediastinal and/or hilar masses were imaged by computed tomography (CT) and magnetic resonance imaging (MRI). Results were analyzed retrospectively regarding the ability to demonstrate the masses, their number, size, definition, location and tissue characteristics. CT and MRI showed equivalent results in 32 cases; additional information was obtained in two patients by CT, in four patients by MRI. In view of the specific advantages and limitations of both CT and MRI we believed that in patients with mediastinal and/or hilar masses, contrast enhanced CT remains the procedure of choice after performing plain chest radiographs; in certain cases MRI will prove useful for further evaluation.     

艾滋病肺门纵隔淋巴结结核的影像学表现

目的探讨获得性免疫缺陷综合征(AIDS)合并肺门和纵隔淋巴结结核的影像学表现。方法回顾性分析9例AIDS合并肺门和纵隔淋巴结结核的影像学表现(包括胸部平片、CT和MR扫描)。全部病例均作了胸部平片、CT扫描，5例作了增强CT扫描，1例作了MR检查。结果AIDS合并肺门和纵隔淋巴结结核时，增大的淋巴结主要位于7区9／9例，4R区7／9例，2R区5／9例。结论AIDS合并肺门和纵隔淋巴结结核的影像学表现为多组淋巴结增大，可相互融合及出现淋巴结外侵犯表现，CT和MR扫描对本病的诊断有重要意义。     

纵隔型肺癌的CT及MR表现分析

目的 探讨纵隔型肺癌CT及MRI诊断能力.方法 回顾分析15例经纤支镜、穿刺活检及手术病理证实为纵隔型肺癌的CT及MRI影像资料,15例全部行CT平扫,其中11例增强扫描,3例行MR平扫与增强扫描.分析CT及MRI图像上肿块的位置、大小、形态、边缘及其与纵隔和肺的关系.结果 15例纵隔型肺癌为单发肿块,5例小细胞型肺癌,8例鳞癌、腺癌及腺鳞癌各1例.肿块均位于纵隔胸膜下,与纵隔呈宽基底相贴,大多呈类圆形或椭圆形.边缘分叶12例,毛刺9例.肿块位于上纵隔8例,中纵隔5例,下纵隔2例.其中前中纵隔区12例,后纵隔3例.肿块与肿大淋巴结融合7例.癌肿邻近相应支气管变窄或闭塞9例.4例有胸廓骨转移性骨质破坏.结论 纵隔型肺癌易误诊,仔细分析CT及MRI表现,结合临床可作出较准确的诊断.     

MR imaging of the chest: Mediastinum and chest wall

This review presents the options and limitations of MRI in non-vascular diseases of the mediastinum and the chest wall. In numerous thoracic pathologies, MRI is a useful supplement to spiral CT. This imaging procedure also allows a contrast-media-free differentiation of solid tumors and vascular lesions (e. g., aortic aneurysms). The advantages of MRI over CT are particularly useful when multiplanar tumor imaging is required prior to surgery to establish the exact spatial relationship between tumor and the other mediastinal structures. Primary indications for MRI in diseases of the mediastinum and chest wall are therefore: (a) tumors of the posterior mediastinum for determining their position in relation to the neural foramina and the spinal canal; (b) chest wall tumors; (c) preoperative multiplanar imaging of primary mediastinal tumors; and (d) contraindications against CT exams with iodine contrast media.     

MR imaging in the management of thoracic malignancies

CT remains the modality of choice for evaluating patients with a thoracic malignancy. In specific cases MR imaging can provide useful information that cannot be obtained with CT, and thus is useful as a problem solving tool. Advantages of MR imaging include superb demonstration of vessels and vessel/mass relationships, direct multiplanar imaging capability, and the potential for tissue characterization. MR imaging is useful in staging the patient with lung cancer when vascular or mediastinal invasion is in question. Its specific applications in surgical planning include the question of chest wall invasion, brachial plexus involvement, and transgression of the diaphragm, pericardium, or lung apex. Multiplanar imaging is useful in radiation therapy planning, displaying lesion extent in a coronal or sagittal format rather than on multiple axial images. Multiplanar capability also resolves problem areas for CT such as the aortopulmonic window, subcarinal region, and lesions at the cervicothoracic or thoracoabdominal junction. Structures such as the trachea and superior vena cava can be evaluated in their plane of anatomic orientation. Routine spin-echo and fast (GRASS) imaging of mediastinal vessels is useful in the evaluation of venous thrombosis as a result of catheters or tumors. The diagnosis and follow-up are obtained without the use of intravenous contrast material or radiation. When CT cannot evaluate vessels adequately because of surgical clip artifacts or postoperative distortion of anatomy, MR imaging is useful in the determination of vessel patency as well as identification of tumor recurrence. Cardiac masses are very well demonstrated by MR imaging. A unique feature of MR imaging is its potential for tissue characterization and ability to assess disease activity. Lymphoma evaluation is an active area of research. MR imaging can evaluate the radiated patient for tumor response and recurrence. Fibrous tissue remains of low signal intensity on T2-weighted images, whereas tumor has increased signal intensity. MR imaging may detect tumor recurrence before an increase in the size of a residual lymphoma mass and before clinical recurrence is evident. The area of increased signal can also serve as a guide to the appropriate site for biopsy to confirm recurrence. In addition, MR imaging can help characterize some adrenal and liver masses, potentially helping to avoid more invasive diagnostic procedures. At the current time MR spectroscopy does not have a clinical role in thoracic malignancies, but it may be a powerful tool in the future for diagnosis and management.     

Magnetic resonance imaging of mediastinal and hilar masses: comparison with CT

Magnetic resonance imaging (MRI) was compared to computed tomography (CT) of the mediastinum and/or hila in 37 patients with bronchogenic carcinoma (35 unresectable for cure) and 11 patients with other masses. Spin-echo pulse sequences using a short pulse repetition rate (TR) and short echo delay (TE) were most helpful for detection of abnormal soft-tissue mediastinal and hilar masses. The accuracy of MRI and CT in staging bronchogenic carcinoma for curative resectability/nonresectability was comparable. CT staged 35 of 37 cases appropriately, while MRI correctly staged 36 of 37 cases. Several pitfalls in MRI evaluation of the mediastinum were identified. By MRI the esophagus may be misinterpreted as an enlarged retrotracheal lymph node unless serial scans are studied. Scattered calcifications in enlarged mediastinal and hilar lymph nodes due to old granulomatous disease are not detectable by MRI. Small adjacent lymph nodes shown individually by CT may appear as a single enlarged lymph node by MRI due to partial-volume averaging. Small lung nodules may be undetected by MRI due to respiratory motion and partial-volume averaging. Certain patients are unsuitable for MR scanning. Because of the requirement for patient selection and the identified pitfalls of MRI, CT remains the radiologic procedure of choice in the staging of patients with bronchogenic carcinoma and the evaluation of other mediastinal and hilar masses at present. However, because of the ability to show blood vessels without an intravascular contrast agent, MRI is useful in evaluating patients with potential contrast allergy and solving diagnostic problems not solved by CT.     

Diagnosis of chest wall invasion by lung cancer: useful criteria for exclusion of the possibility of chest wall invasion with MR imaging

PURPOSE: To compare the accuracy of thin-section CT, conventional static MR imaging (conventional MRI), and breathing dynamic echo planar magnetic resonance imaging (BDEPI) in evaluating lung cancer invasion to the chest wall. MATERIALS AND METHODS: Thin-section CT, conventional MRI, and BDEPI were performed preoperatively in 20 patients suspected of having primary lung cancers adjacent to the chest wall on conventional CT. The results of imaging findings were compared with those of surgical and histopathological findings. RESULTS: All patients were confirmed to have no chest wall invasion after surgery. By thin-section CT, 10 of 20 patients were correctly diagnosed as having no chest wall invasion (50% specificity). Two of the 20 patients were incorrectly diagnosed as having chest wall invasion by conventional MRI and BDEPI (90% specificity). CONCLUSION: When chest wall invasion is suspected on CT scans, static and breathing dynamic MRI are recommended to avoid false positive interpretations.     

Anterior mediastinal tumors: diagnostic accuracy of CT and MRI

Purpose

To compare the diagnostic accuracy for anterior mediastinal tumors among CT, MRI, and both CT and MRI, and to determine the optimal CT and MRI procedures for the diagnosis of anterior mediastinal tumors.

Materials and methods

Both CT and MRI were performed in 127 patients with pathologically diagnosed anterior mediastinal tumors. The patients included 48 cases of thymoma, 12 cases of thymic carcinoma, 12 cases of thymic cyst, 20 cases of mature teratoma, 13 cases of malignant germ cell tumor, and 22 cases of malignant lymphoma. The CT and MRI scans were assessed by two chest radiologists without knowledge of their clinical and pathologic data. The observers recorded various CT and MRI findings and their first choice of diagnosis.

Results

The two observers made a correct first-choice diagnosis in an average of 78 (61%) of 127 cases on CT, 71 (56%) of 127 cases on MRI, and 85.5 (67%) of 127 cases on both CT and MRI. These included 83% cases of thymoma on CT, 84% on MRI, and 85% on both CT and MRI; 38% cases of thymic carcinoma on CT and 13% on MRI, and 33% on both CT and MRI; 46% cases of thymic cyst on CT and 71% on MRI, and 63% on both CT and MRI; 58% cases of mature teratoma and 38% on MRI, and 78% on both CT and MRI; 35% cases of malignant germ cell tumor on CT and 27% on MRI, and 31% on both CT and MRI; and 55% cases of malignant lymphoma on CT and 43% on MRI, and 61% on both CT and MRI. There were significant differences between the diagnostic accuracy by CT and MRI in the cases with both thymic cysts and thymic carcinoma (p < 0.05).

Conclusion

CT is equal or superior to MRI in the diagnosis of anterior mediastinal tumors except for thymic cyst. CT should be considered the modality of choice following chest radiography, however, in certain circumstances, such as thymic cyst with hemorrhage or inflammation which mimic solid tumor despite low enhancement, MRI may be better in distinguishing anterior mediastinal tumors. For more helpful information in the diagnosis of mature teratoma after CT, MRI may follow.     

Computed tomography and magnetic resonance imaging in cystic fibrosis lung disease

Computed tomography (CT) is the current "gold standard" for assessment of lung morphology and is so far the most reliable imaging modality for monitoring cystic fibrosis (CF) lung disease. CT has a much higher radiation exposure than chest x-ray. The cumulative radiation dose for life-long repeated CT scans has limited its use for CF patients as their life expectancy increases. Clearly, no dose would be preferable over low dose when the same or more relevant information can be obtained. Magnetic resonance imaging (MRI) is comparable to CT with regard to the detection of most morphological changes in the CF lung. It is thought to be less sensitive to detect small airway disease. At the same time, MRI is superior to CT when it comes to the assessment of functional changes such as altered pulmonary perfusion. The recommendation is to further reduce radiation dose related to the use of CT and to use MRI in the follow-up of morphological changes where possible.     

Magnetic resonance imaging in the study of pulmonary hilar involvement

A retrospective analysis of results of magnetic resonance imaging (MRI) was conducted in 28 patients with uni- or bilateral pulmonary hilum lesions and findings compared with those of computed tomography (CT). All abnormal hilar masses examined were between 1 and 5 cm in diameter and were easily detected by transverse axial imaging. Contrast of their images was very high in relation to hilar bronchovascular elements in the two types of spin echo sequence with a short TR (0.5-0.7 s) and a long TR (1.5-2 s). Differentiation between tumoral or adenopathies and vessels was simpler than with CT with intravenous contrast. For screening of possible extension of hilar tumors. MRI appears to be superior to CT for providing data on vascular relations of lesions but inferior to CT for determining bronchial relations. Mediastinal extension of hilar tumors is easily defined by the short TR sequence but MRI supplies data of greater value than CT only in a low proportion of cases and then partly as a result of complementary coronal and sagittal imaging.     

胸部脂肪瘤的影像学诊断(附14例报告)

目的探讨胸部脂肪瘤的影像学表现及检查方法优选. 资料与方法搜集胸部脂肪瘤14例资料,包括肺脂肪瘤2例,胸壁脂肪瘤4例,纵隔脂肪瘤3例,胸腺脂肪瘤3例,横膈脂肪瘤1例,右心房脂肪瘤1例,全部病例均有胸部正侧位片,12例进行了CT检查,1例进行了MRI检查,对全部患者的影像学表现进行分析. 结果胸部正侧位片病灶发现率78.6%,漏诊原因与肿瘤密度过低,肿瘤沿胸壁深部肌间隙浸润生长或肿瘤位于平片上较隐蔽的部位有关.CT检查不仅可进行精确的定位诊断和分类诊断,而且能作出定性诊断,但应常规摄脂肪窗片.MRI对这类肿瘤最敏感,它对病变的发现、定位、分类诊断及定性诊断有决定性意义. 结论胸部正侧位片是胸部脂肪瘤的首选检查方法,但病变的分类诊断与定性诊断需依赖胸部CT与MRI,其中MRI是该类疾病的最佳检查方法.     

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.