ROUTINE FULL-LUNG TOMOGRAPHY IN THE INITIAL STAGING AND TREATMENT PLANNING OF PATIENTS

WITH HODGKIN’S DISEASE AND NON-HODGKIN’S LYMPHOMA

ROXALD A. CASTELLINO, MD, ROY FILLY, MD* AND NORMAN BLANK, MD

The yield of additional information from anteroposterior full-lung tomograms that changed stage or treatment, in comparison to that obtained from routine chest radiographs, was prospectively evaluated in 243 previously untreated patients with Hodgkin’s disease and non-Hodgkin’s lymphoma. Although new information was found in 21.4% of all patients, in only 1.2% did these addi- tional data change patient staging. In 3.3% of the other patients the tomograms provided information that affected radiotherapy treatment planning as prac- ticed in our institution.

Cancer 38:1130-1136. 1976.

OUTINE FRONTAI FULL-LUNG TOhfOGKAPHY IS R advocated as a diagnostic procedure for staging patients with lymphoma, since the diag- nostic benefits derived from this radiographic examination in patients with Hodgkin’s disease are generally understood to be great. Indeed, full-lung tomography has been routinely em- ployed in the initial diagnostic evaluation of pre- viously untreated patients with Hodgkin’s dis- ease and non-Hodgkin’s lymphoma seen at the Stanford Medical Center for the past 15 years. However, we were unable to find a carefully controlled prospective study indicating the mag- nitude of useful information gained from tomog- raphy in comparison with that available from the routine chest films. We, therefore, decided to test the value of full-lung tomography prospec- tively in terms of diagnostic yield in comparison with that achieved from using stereoscopic pos- terior-anterior (P-A) and left lateral tele- roentgenograms of the chest.

If full-lung tomography is to be used rou- tinely, then one should rxpect that this exam-

From the Ilivision of Iliagnostic Radiology, Department of Radiology. Stanford trniversity School of kfedicine, Stan- ford. California.

Supported by grant CA-05838, National Cancer Institute, National Institutes of Health, and GM-1707. National In- stitute of General Medical Sciences.

* .Academic Trainee in Diagnostic Radiology, National Institute of General hledical Sciences.

Address for reprints: Ronald A. Castellino, MD, Depart- ment of Radiology, Stanford University School of hfedicine, Stanford. (:A 0430.5.

Received for publication November 6, 197.5.

ination will affect clinical management by pro- viding information not derived from the plain films Such information includes findings that change the staging of the disease (often resulting in different treatment options), or that signifi- cantly alter the therapeutic approach. At Stan- ford hledical Center, radiotherapy treatment planning is, in part, dependent on the radio- graphically visualized distribution of disease in the chest. Analysis of the mode of spread of Hodgkin’s disease suggests the advisability of treating the ipsilateral lung in those patients who manifest hilar adenopathy, even when there is no detectable pulmonary parenchymal le- sion lo Therefore, the absence or presence of hi- lar (bronchopulmonary) lymphadenopathy will altrr radiotherapy treatment planning with re- gard to use of thick versus thin lung shielding blocks, respectively. 7 9 9 T o decrease the incidence of radiation-induced heart disease, precordial blocks are placed approximately two-thirds of the way through the mantle radiation. However, the presence of low posterior mediastinal, para- cardiac, or large subcarinal components of adenopathy will alter the timing of the place- ment of the precordial blocks.”’

MATERIALS A N D METHODS

€rom January, 1971, to August, 1973, 300 consecutive, previously untreated patients with histologically confirmed Hodgkin’s disease (1 64 patients) and non-Hodgkin’s lymphoma (136 patients) were entered into various treatment protocol studies; these patients form the basis of

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No. 3 FULL-LUNG TOMOGRAPHY Castellino et al. 1131

this report. The details of the protocols are not important to the present analysis, but are avail- able to the interested reader. 6 3 7 All patients were prospectively studied with stereoscopic P-A and left lateral chest radiographs as part of their initial diagnostic evaluation. In addition 243 (81%) of these patients had full lung anterior- posterior tomograms performed on the same day as the plain chest examination [148 patients with Hodgkin’s disease (90%) and 95 patients with non-Hodgkin’s lymphoma (70%)] . Forty patients, all of whom had full-lung tomograms, had lateral tomograms as well.

The discrepancy between the number of patients undergoing tomography compared with those having stereoscopic chest films (243 vs. 300) resulted from two major factors. First, patients with established stage IV disease often did not have tomograms, since little additional useful information regarding treatment could be gained. Second, there were 35 patients with non- Hodgkin’s lymphoma who did not have tomo- grams because their preliminary chest films were considered unequivocally normal and tomography was not a routine part of their pro- tocol work-up.

Lung tomography* was performed with the patient supine. Tomographic cuts were obtained at 1.0-cm intervals from a posterior level at which the posterior ribs were in sharp focus (usually 3-4 cm from table top) to an anterior level just beyond that on which anterior ends of the 5th or 6th ribs were in sharp focus (usually 16-20 cm from the table top). All films were reviewed before the patient left the department, and when indicated, 0.5-cm cuts were made about those levels where questionable shadows were seen. In addition, lateral and upright cuts were made when indicated.

At the time of film interpretation, the stereo- scopic P-A and left lateral films of the chest were analyzed first as to the presence or absence of mediastinal (including anterior mediastinal, paratracheal, tracheobronchial, subcarinal, pos- terior mediastinal, internal mammary, and par- acardiac groups) and hilar (bronchopulmonary) lymphadenopathy, as well as to the presence or absence of pulmonary parenchymal, pleural, and bony abnormalities. The tomograms were

* T h e tomograms were performed on a Siemens’ linear tomographic unit. T h e target-film distance was 140 cm and the focal spot sizes were 0.6 mm (small) and 2 mm (large). Nineteen degrees of the tube travel gave a 2.5 mm layer in sharp focus and a less sharp but usable image for 2 mm on both sides of this plane. Tube settings varied from 80 to 100 kVp and 20 to 30 mAs, depending on body habitus. A con- toured “trough” aluminum filter was used on most studies.

then analyzed for these same variablcs. Specifi- cally, we sought those instances in which the tomograms showed sites of disease that were not apparent on the plain chest films, and that po- tentially could alter staqing or radiotherapy treatment. We considered instances in which the tomograms showed additional disease that did not influence staging or treatment to be of less importance, since such information did not change patient management. We did not ana- lyze instances in which the plain chest films showed lesions that were not demonstrated on tomography, since we felt that no one would study a patient with full-lung tomograms with- out having preliminary plain films of the chest.

Significant discrepancies were defined as fol- lows:

1 . Tomograms showed evidence of in- trathoracic involvement with tumor when the plain chest radiographs showed no evi- dence of neoplastic disease.

2. Tomograms showed an additional area of mediastinal lymph node involvement, when compared with plain films, which al- tered radiotherapy treatment planning in our institution due to the nodal location (i.e., low paravertebral, large subcarinal, or paracardiac lymphadenopathy).

3 . Tomograms showed evidence of hilar adenopathy when the plain chest radio- graphs were considered negative for this node group, since this alters radiotherapy treatment planning at our institution.

4. Tomograms showed evidence of pul- monary parenchymal disease consistent with involvement by tumor when the plain films were considered negative for lung in- volvement. I t was not considered a signifi- cant discrepancy when plain films revealed pulmonary parenchymal lesions and tomo- grams simply demonstrated additional le- sions in the same lung, unless radiotherapy fields or staging were altered by this new information.

5 . Tomograms showed evidence of bone or pleural disease not seen on plain films.

Confirmation of radiographic findings was only occasionally based on histopathologic proof. Regression of a radiographic abnormality following therapy was the major criterion for the proof of malignant involvement.

1132 CANCER September 1976 Vol. 38

RESULTS (FIG. 1 )

The following results must be evaluated in terms of the type of radiotherapy treatment planning employed at our institution, which is dependent on the radiographically visualiced dis- tribution of disease in the chest as noted above. Of the 243 patients undergoing tomography, no new information was found in 191 cases (78.670). Although there were 52 (21.4%) patients with discrepancies between their plain chest radiographs and AP full-lung tomograms, in 36 (14.8%) patients the new information did not alter stage or treatment. Therefore, in 227 of 243 (93.470) patients no significant new informa- tion was gained by performing AP full-lung tomograms.

There were 16 patients in whom the tomog- rams showed additional sites of disease that changed either staging, treatment, or both. These sites were either not apparent (11 patients), or were suspected, but not definite (five patients) on the plain films. The five patients (2%) with suspected abnormalities on the plain films had these findings definitely con- firmed on tomography (four cases of hilar aden- opathy and one case of lung involvement). These patients are not considered to represent unex- pected new information on “routine” tomog-

raphy since we assume that one would ordinar- ily pursue suspected plain film abnormalities with tomography if a positive finding would al- ter stage or treatment.

Eleven patients showed lesions on tomo- graphy that were not suspected on the plain films and that altered either stage (three patients) or treatment planning (eight patients). It is worth noting that 10 of these 11 patients had Hodgkin’s disease, suggesting that tomog- raphy is of more usefulness in this group. In the three patients (1.270) for whom the stage was altered, two showed unsuspected superior me- diastinal adenopathy (Fig. 2) and the third, an unsuspected lung nodule.

In the eight patients (3.3%) for whom radio- therapy port planning was altered, all had ob- vious intrathoracic involvement on plain chest examination but tomography showed additional sites of disease. One patient each showed in- volvement of mid- and low paravertebral node groups; three patients showed involvement of the subcarinal nodes; and one patient showed paracardiac adenopathy. The remaining two patients showed both subcarinal and para- cardiac adenopathy not apparent on the plain films.

The treatment planning in these eight patients was influenced by modification of the

100% (243 PTS)

1

N E W INFORPI lATlON I N 21 .4% (52 PTS)

N O N E W I N F O R M A T I O N I N - 78 6’” ( 1 9 1 PTS)

I N W H I C H S T A G E O R T R E A T M E N T

W A S A L T E R E D I N 6 6% ( 1 6 PTS)

W A S N O T A L T E R E D IN 14 EnL ( 3 6 PTSI

N O C H A N G E I N S T A G E O R

93 4% (227 PTS)

t L E S I O N S SUSPECTEO O N I N F O R M A T I O N C H A N G E 0 T H E I N F O R M A T I O N C H A N G E O T H E

S T A G E O F P O R T S I N M O O l F l E O M A N T L E P L A I N F I L M S W E R E CON

1 2% (3 PTS) OISEASE R A D I O T H E R A P Y T R E A T M E N T F I R M E D O N T O M O G R A P H Y T R E A T M E N T

3 300 (8 PTS) 2 1’4 (5 PTSI

FIG 1. Hrsults of routine full-long tomography in 243 prospertively studied patients with newly diag- nosrd Ilodgkin’s disease and non-Hodgkin’s lymphoma.

No. 3 FULL-LUNG TOMOGRAPHY Castellino et al . 1133

Fin. 2. 21-year-old man with Hodgkin’s disease. The standard chest radiograph (left) on,June 9 was interpreted as being normal. whereas the supine AP tomograms (middle) on the same day showed a mass (arrow heads) overlying the inferior aspect of the transverse portion of the aortic arch. Following mantle radiotherapy (June 30) repeat tomograms (right) showed resolution of this mass, presumed to represent adenopathy due to Hodg-kin’s disease

shaping and timing of placement of the pre- cordial block, in order to increase dosage to those areas that would ordinarily be shielded by this technique. In four patients with lymphaden- opathy predominantly extending into the sub- carinal region, the precordial blocks were smaller than usual and were placed at a later stage in the course of treatment. In the other four patients with lymphadenopathy extending to the level of the diaphragm, the precordial blocks were not placed at all.

There were two additional patients who showed evidence of intrathoracic lymph node involvement on the plain films and AP tomo- grams, but disease involving lung parenchyma became apparent only on lateral tomographic cuts (Fig. 3). There were two other instances where parenchymal disease was suspected on the plain films and confirmed on lateral tomo- grams.

One hundred patients showed no evidence of intrathoracic malignant disease on plain films. Four of these displayed evidence of superior me- diastinal adenopathy (three patients) or para- cardiac adenopathy (one patient) on tomog- raphy. Two of these patients had superior mediastinal distortions on plain films due to tortuous vessels and scoliosis, and supine tomog- raphy showed components of superior medias- tinal adenopathy. The recognition of malignant

disease in the thorax on tomography in a patient whose plain chest radiograph is interpreted as showing no evidence of malignant disease could potentially change patient staging. However. two of these four patients already had stage IV disease based on positive bone marrow aspirate. Thus, the recognition of these areas of in- volvement (paracardiac adenopathy in one case, and superior mediastinal adenopathy in the other) did not alter the staging or treatment planning in these two patients. The remaining two cases (superior mediastinal adenopathy in both), whose stage was altered by the tomogra- phic findings, have already been discussed above.

In summary, the yield from routine A-P full- lung tomograms in terms of changing patient staging was 1.2%. In our institution, which em- ploys modified mantle radiotherapy depending upon the radiographic distribution of in- trathoracic disease, the yield from full-lung tomograms affecting treatment management was an additional 3.3% of all patients.

DISCUSSION

Full-lung tomograms, made using careful technique and small intervals between levels, would seem intuitively to add materially to the accuracy of detecting mediastinal, hilar, and pa-

1134 CANCER September 1976 Vol. 38

renchymal abnormalities in patients with Hod- gkin’s disease and other forms of malignant lym- phoma. In our study, this was indeed the case, since in 21.4% of our patients additional sites of disease were seen on tomograms that were not apparent on plain chest films. However, only 1.2% of the patients studied had a change in treatment planning due to a change in staging their disease, while an additional 3.3% of these patients had a change in treatment planning due to the radiotherapeutic approach employed at Stanford Medical Center.

The yield of information obtained by rou- tinely performed full-lung tomography was con- siderably greater in patients with Hodgkin’s disease (10/148 or 6.7%) than in those with non-Hodgkin’s lymphoma (1/95 or 1.1%). T h e routine use of full-lung tomography in patients with non-Hodgkin’s lymphoma appears to be of little value.

The plain chest films and tomograms were interpreted by faculty in the Diagnostic Onco- logic Radiology section,’ who are especially in- terested in studying variations in mediastinal contours that might permit early diagnosis of adenopathy from the routine films alone. ‘.‘This experience may have influenced their approach

to the plain film findings and decreased the number of times that significant additional evi- dence of mediastinal adenopathy was gained from tomograms.

In general, tomograms accentuate abnormal- ities of mediastinal and hilar contours. This is brought about in large part by the detection of the interfaces between these abnormal contours and contiguous lung free of overlying shadows in ad.jacent planes. In addition, the shorter target- film distance used in tomography, compared with conventional chest radiography, magnifies the abnormalities. One must recognize, how- ever, that striking changes may occur in medias- tinal width simply between films obtained with the patient upright and supine. This is most marked in those who are obese or of mesomor- phic habitus. Therefore, abnormalities of con- tour are more reliable signs of adenopathy than is mediastinal width alone.

T h e subcarinal (intertracheobronchial) group of lymph nodes remains for us the most difficult mediastinal group to assess, because they do not impinge on lung and pleural recesses until they are reasonably large. In addition, one must be cautious not to diagnose prominent confluences of veins adjacent to the left atrium erroneously

FIG. 3. An 18-year-old man with Hodgkin’s disease. (A) Standard chest radiographs showed a large, lobulated superior mediastinal, subcarinal and right hilar mass, confirmed on supine AP full-lung tomog- raphv. No pulmonary parenchymal lesions were seen.

No. 3 FULL-LUNG TOMOGRAPHY 9 Castellino et al. 1135

FIC 3(B) . Lateral tomograms of patient in Fig. 3A showed at least two discrete nodules (lines) in the antero-medial portions of the right upper lobe. Note the prominent right hilar adenopathv.

as abnormal lymph nodes. At times, a barium swallow may be helpful in demonstrating im- pingement from abnormal nodes, but enlarge- ment may be considerable before esophageal im- pingement is manifest.

We have found the use of lateral tomographic cuts very helpful in evaluating hilae that are equivocally abnormal, or in those cases where massive mediastinal adenopathy overlaps the hi- lar regions on the AP tomograms. In addition the lateral tomograms may be valuable in de- tecting parenchymal involvement in those cases where massive mediastinal nodes obscure the medial portions of the upper and middle lung zones.

As general guidelines for determining which patients with newly diagnosed Hodgkin’s dis- ease or non-Hodgkin’s lymphoma may benefit most from lung tomography in terms of in- fluencing treatment planning we suggest that:

1. Patients with equivocal abnormalities on plain films require further investigation with tomography.

2. Those patients with bulky mediastinal adenopathy obscuring hilar regions and lung parenchyma can have the extent of their disease more precisely defined with tomograms, including lateral tomograms.

3 . Tortuous superior mediastinal vessels or thoracic cage deformities, such as scoliosis, may obscure malignant disease due to the altered anatomy, and plain films alone may he misleading.

4. Routine full-lung tomograms have an extremely low yield of pertinent additional information in patients with unequivocally normal stereo PA and lateral chest films.

Finally. we acknowledge that our study has compared the information offered by stereo- scopic PA and lateral chest films with that of full-lung tomography, and we have not tested, in this comparison, the potential contributions that

1136 CANCER September 1976 Vol. 38

might be made by routine fluoroscopy (with gus), oblique films of the chest, or other special study of the course of the barium-filled esopha- views.

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