Xerotomography of peripheral lung lesions.

Xerotomography of peripheral lung lesions. N F Maklad, Y M Ting and K P Ravikrishnan Chest 1976;69;516-518 DOI 10.1378/chest.69.4.516 The online version of this article, along with updated information and services can be found online on the World Wide Web at: http://chestjournal.chestpubs.org/content/69/4/516

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Xerotomography of Peripheral Lung Lesions* Nabi2 F . Maklad, M . D . ; 0 4 Y . M . Ting,M.D.;? and K . P. Raoikrishnan, M.D., F.C.C.P.:

Xerotomography was compared to conventional tomography in 72 patients with peripheral lung lesions The xerotomogram was superior to the conventional tomogram in 41 patients, and yielded no additional information in 31. Details of lesions were better displayed, especially the margins: cavitations, air bronchogram and bronchiectasis, and calcification. Differentiation between

benign, Mammatory and malignant lesions was thus facilitated. The xerotomographic process improved the image detail of lesions due to the edge enhancement property and the greater recording latitude of contrast of the xeroradiographs. Xerotomography is recommended only in selected patients for a few tomographic cuts because of the high radiation dosage.

eroradiography has become an important technique for the evaluation of breast masses.l Recently, its use has extended to the examination of the and the soft tissues, bones of the extremitie~,~ larynx.3 In the chest, xerotomography has provided superior demonstration of the mediastinum, trachea and b r ~ n c h i .At ~ Wayne County General Hospital xerotomography has almost replaced bronchography for evaluation of the central tracheobronchial tree and hilar m a s s e ~ . ~ . ~ Tomography ( body section radiography ) is a widely used technique in the radiologic investigation of peripheral lung le~ions.~ However, small foci of calcification and small cavities are not seen clearly, and the relationship of the peripheral bronchi and vessels to the lesions are poorly demonstrated. For the past two years, therefore, we have used xerotomography to complement the conventional chest tomograms.

The technique for XTG consisted of repeating the chosen tomographic cuts, substituting a xeroradiographic plate cassette for the x-ray film cassette. A tomographic angle of 30° (thin cut) was used for small lesions, and !?Do(thidc cut), for larger lesions. The technical factors used for both conventional tomography and XTG are given in Table 1. Similar tomographic and xerotomographic cuts were compared by two radiologists.

Xeroradiography utilizes an electrostatic x-ray imaging system based on the photoconductive properties of selenium. For a more detailed discussion of the process, the work of Wolfe7 should be consulted. Seventy-hvo patients with peripheral lung lesions were studied by regular tomograms and xerotomograms. The age of the patients ranged from 42 to 83 years. From the conventional tomographic cuts, one to three pertinent cuts were selected for xerotomography (XTG). 'From the Departments of Radiology and Pulmonary Disease, The University of Michigan, AM Arbor, and Wayne County General Ho ital, Eloise, Michigan. "Assistant Professor z ~ a d i o l o g y . tAssociate Professor of Radiology. :Clinical Instructor in Medicine. Manuscript received September 8; revision accepted November 5. Reprint requests: Dr. Maklad, Radiolo y Department, Wayne County General Hospital, Eloise, ~ i c f i g a n

516 MAKLAD, TING, RAVIKRISHNAN

Xerotomography showed definite improvement in the image and added significant detail in 41 of 72 patients. No additional information was obtained in the other 31 patients. In the 41 patients in whom XTG was superior to the similar regular tomograms, the following results were observed: 1) better definition and delineation of the lesion. The character of the margins of the lesion, whether lobular, irregular or spiculated, was assessed with greater ease and accuracy on the XTG in 12 patients (Fig l a and l b ) . 2 ) The presence of patent air-filled bronchi within the lesion (air bronchogram) or dilated bronchi ( bronchiectasis ) was better demonstrated on XTG in 14 patients. Patent and/or dilated bronchi indicate an inflammatory etiology (Fig 2a and Table 1--Comparison o f Conventional Tomogram and Xerotomography

Tomographic Examination Angle KVp mAs Conventional tomogram XTG

20" 20"-30"

70

Radiation Exposure Distance (r) (Average)

30-60

120 80-120

Xeroradiographic Processing:

40"

0.14

40"

1.33

Contrast Density Mode -D

A or D

Neg

CHEST, 69: 4, APRIL, 1976


h u ~ l ea (left). Regular tomogram h 15 cm reveals a lobulated mass with a peripheral radiolucency suggesting cavitation. FIGURE l b (right). Xerotomogram at 15 cm.The lobulatecl borders of the mass are better defined. Note the spiculation of the margin and the peripheral cavity. Pathologic diagnosis: carcinoid tumor of the lung.

2b). Obstructed and encased bronchi suggest malignancy (Fig 3). 3 ) Cavitation within a peripheral lung lesion and the character of the wall of the cavity were better seen on XTG in 17 patients (Fig l b ) . Nodularity and irregularity of the wall of the cavity were well demonstrated (Fig 3). In addition, patent bronchi leading to a cavity, seen on XTG,were not always evident on the regular tomograms (Fig 2a and 2b). 4 ) Central or peripheral calcifications

in a nodule stand out clearly on XTG.In four cases, xerotomography revealed calcification within a nodule not seen on plain films or conventional tomograms. In the 72 patients studied, xerotomography was more definite in providing clues for the correct diagnosis in 29 (40 percent): tumor in eight, inflammatory lesion in 17 and granuloma in four patients, whereas the conventional tomograms in these pa-

FIGURE 2a ( l e f t ) . Tomogram of the left upper lobe reveals an irregular lesion with central radiolucency suggesting cavitation. FIG^ 2b (right). XTG at the same level as Figure 2a. Thickwalled cavity is clearly seen. The inner wall of the cavity is smooth. Note the patent, moderately dilated bronchus leading to the cavity ( a r m ) not clearly seen on the conventional tomogram. Pathologic dtagnosis: chronic lung abscess.

CHEST, 69: 4, APRIL, 1976

XEROTOMOGRAPHY OF PERIPHERAL LUNG LESIONS 517


lung le~ions.~ It is important, therefore, that every effort be made to distinguish malignant from benign and inflammatory lesions. Parameters which aid in differentiation of neoplastic from benign lesions are: lung mass interface, presence and characteristics of calcification, cavitation and the appearance of the cavity wall, and patency of bronchi. Xerotomography is superior to conventional tomograms for evaluating these parameters in many instances (41 of 72 patients) because of the edge enhancement quality of xeroradiographic process. Interpretation of the tomographic study is also made easier because of the greater contrast latitude of XTG. Bronchi, vessels, aerated lung and bone are well seen on the same cuts. Xerotomography is a useful adjunctive technique to conventional tomograms in the radiologic investigation of peripheral lung lesions. Because of the higher radiation dosages in XTG, only selective cuts should be performed.

RE-CES FIGURE 3. Xerotomogram. Irregularity and nodulation of a thick-walled cavity are clearly seen. In addition, the right upper lobe bronchus (arrow) shows rattail-like obstruction. The bronchus intermedius is irregularly narrowed (arrows) due to encasement by tumor tissue. These were not well seen on the regular tomogram. Pathologic diagnosis: cavitating squamous cell carcinoma.

tients were equivocal. In the remaining 43 patients, there was no difference in diagnostic accuracy between the two modalities.

About 40 percent of pulmonary neoplasms are peripheral and in one-third of the cases, the peripheral mass is the sole radiologic abnormality. Pulmonary metastases also cause problems in differential diagnosis, since they may appear first as peripheral

1 Wolfe JN: Xeroradiography of the Breast. Sprinsfield, Ill, Charles C Thomas, 1972 2 Wolfe JN: Xeroradiography of the bones, joints and soft tissues. Radiology 93:583-587, 1969 3 Doust BD, Ting YM: Xeroradiography of the larynx. Radiology 110:727-730, 1974 4 Chuang VP, Doust BD, Ting YM: Xerotomography of the mediastinum and tracheobronchial tree. Radiology 111:475477,1974 5 Ting YM, Doust BD, Chuang VP: Xerotomographic diagnosis of central bronchogenic carcinoma. Chest 67: 172-175, 1975 6 Rigler LG, Heikman ER: Planigraphy in the differential diagnosis of the pulmonary nodule. Radiology 65692-702, 1955 7 Wolfe JN: Xeroradiography: Image content and comparison with film roentgenograms. Am J Roentgen 117:690695,1973 8 Heikman ER: The Lung: Radiologic-Pathologic Correlations. St. Louis, C.V. Mosby, 1973

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Xerotomography of peripheral lung lesions. N F Maklad, Y M Ting and K P Ravikrishnan Chest 1976;69; 516-518 DOI 10.1378/chest.69.4.516 This information is current as of April 17, 2012 Updated Information & Services Updated Information and services can be found at: http://chestjournal.chestpubs.org/content/69/4/516 Permissions & Licensing Information about reproducing this article in parts (figures, tables) or in its entirety can be found online at: http://www.chestpubs.org/site/misc/reprints.xhtml Reprints Information about ordering reprints can be found online: http://www.chestpubs.org/site/misc/reprints.xhtml Citation Alerts Receive free e-mail alerts when new articles cite this article. To sign up, select the "Services" link to the right of the online article. Images in PowerPoint format Figures that appear in CHEST articles can be downloaded for teaching purposes in PowerPoint slide format. See any online figure for directions.
