When a solitary pulmonary nodule of .3 cm is
detected, a benign diagnosis can be made only if edge
characteristics include a smooth, well-demarcated
contour. Once lesions become spiculated or irregular,
they are far more likely to be lung cancer. Lesions
with a lobular contour or an irregular shape likely
represent bronchogenic carcinoma.
A lesion that has a certain pattern of calcification
can ensure a benign diagnosis. Centrally calcified
lesions are typically granulomas, as are homogeneously
diffuse lesions. The stippled pattern and the
eccentric pattern of calcification frequently seen in
bronchogenic carcinoma may be the result of production
of calcium by the tumor, or (as seen in mucin-
producing adenocarcinomas) infarction due to
vascular overgrowth, or engulfment of a preexisting
granuloma.
Lesions known to be stable over 2 years can be assumed
to be benign, although documenting stability
with historic radiographs and scans may pose considerable
logistic challenges. In general, only welldefined
lesions that measure <3 cm in diameter
should be evaluated for benign characteristics by CT.
The prevalence of malignancy in larger or spiculated
lesions is above 85%. Computed tomography is also
capable of detecting pathologic calcification in lung
cancer (10 to 15% of all lesions). To achieve the best
results, thin section scanning (1 to 5 mm) of the area
294S Multimodality Therapy of Chest Malignancies: Update '94
1995 by the American College of Chest Physicians
Downloaded from chestjournal.chestpubs.org by guest on October 19, 2010
of radiographic abnormality should be used."12
Hamartomas can be diagnosed with confidence if
fat or calcium is demonstrated on CT. In our experience,
they are rarely calcified and rarely contain
fat. Visual inspection of the abnormality with or
without determination of density is usually adequate.
Although some groups have shown success with
lung imaging using metabolically active agents such
as radiolabeled F-18 fluorodeoxyglucose, the procedure
is expensive, requires positron emission scanning
capabilities, and has been performed only
recently in sufficiently large numbers of patients to
warrant further clinical study.3
Contrast-enhanced CT scans that evaluate changing
patterns of enhancement to differentiate benign
from malignant nodules offer another useful imaging
technology.4 Regardless of the imaging mpdality,
however, the end point-a specific diagnosis-is still
the exception. Most solitary pulmonary nodules are
indeterminant; they require further procedures to
reach a definitive diagnosis, usually with fine-needle
aspiration biopsy or resection via thoracoscopy/thoracotomy.
5
MEDIASTINAL IMAGING
Whenever looking at the mediastinum, one must
determine how the information will assist the responsible
specialist in staging the condition of his
patient. Mediastinal CT has many uses, including
demonstrating enlarged nodes and helping to stage
central malignant disease.
The presence or absence of mediastinal lymph
node involvement is of important prognostic significance.
Ideally, any diagnostic method short of tissue
sampling would be welcome, but present techniques
do not allow this. Noninvasive clinical tests for evaluating
the local spread of bronchogenic carcinoma
are lacking. Radiologic imaging offers a wide range
of examination techniques. The chest radiograph
remains very specific but highly insensitive for mediastinal
metastases.
Computed tomography remains the preferred
imaging modality for examining the mediastinum in
patients with NSCLC. The information provided by
the CT scan must then be correlated with results of
various lymph node sampling procedures.
Early studies indicated fairly sensitive and specific
data from CT/pathologic correlation,6 but more accurate
studies clearly show that enlarged lymph
nodes on CT (with a short-axis diameter >1 cm) must
be sampled.7 Knowing the anatomic sites of such
nodes may alter the surgical approach and help
ascertain N2/N3 status as well.
The Radiologic Diagnostic Oncology Group study
comparing CT and MRI showed a slight advantage
for MRI, but not enough to recommend its use in
patients with lung cancer who initially present for
evaluation of mediastinal dissemination.8 Our group
uses MRI in select cases: eg, for anatomic problem
solving, and when the surgeon believes that such information
will be of use. Additionally, MRI is recommended
in all surgical candidates with superior
sulcus tumors.
In assessing mediastinal adenopathy in patients
with lung cancer, a normal CT scan does not preclude
disease, because intranodal or microscopic involvement
is imperceptible on CT. Magnetic resonance
imaging cannot yet characterize the actual contents
(benign vs malignant) of a lymph node.
Although CT is the preferred imaging modality for
mediastinal evaluation, mediastinoscopy or some
other technique should uniformly be used to evaluate
for N2/N3 disease.
EXTRATHORACIC IMAGING
Some clinicians believe that extrathoracic staging
has no valid role in evaluating asymptomatic patients
with NSCLC at initial presentation, and studies have
demonstrated that routine bone, brain, and liver/
spleen scans are unnecessary and potentially misleading
in evaluating lung cancer.9'10 The best method
for determining the presence of metastases remains
a thorough history and physical examination, with
appropriate laboratory studies. Can imaging justifiably
replace this approach?
Autopsy studies of patients who died of lung cancer
have shown frequent extrathoracic metastases.11
The clinical significance of metastases of any cell type
is catastrophic. These metastases primarily involve
the central nervous system (CNS), skeleton, liver,
mediastinal lymph nodes, and adrenal glands and less
commonly the skin, soft tissue, bowel, pancreas, and
kidneys.
By examining issues related to the known frequency
of metastases (often dependent on knowledge
of the cell type of the primary neoplasm) and the
extent of thoracic disease, we can begin to assess the
effectiveness of extrathoracic imaging in evaluating
patients with lung cancer. Because small cell carcinoma
is considered largely a separate entity, only
NSCLC will be considered.
If the patient is a surgical candidate and the chest
CT scan shows no absolute criteria for inoperability,
what is the role of extrathoracic imaging? How is it
supported in the literature? Should all patients with
NSCLC undergo a head CT scan, MRI, bone scan,
and radiographic study of the upper abdomen (ie, the
liver and adrenal glands)? As before, the radiologist's
actions are ultimately guided by the surgeon's choice
and objectives.
Extent of thoracic disease is not a reliable indica-
CHEST / 107 / 6 / JUNE, 1995 / Supplement 295S
1995 by

http://chestjournal.chestpubs.org/content/107/6_Supplement/2...
from this article it seems it describes an irregualr shapt or contour and often indicates carcinoma.
I wonder whether this might help:"unregelmässige Kontur" vielleicht?



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Note added at 2 hrs (2010-10-20 02:28:23 GMT)
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sorry it's lateand I I am just rying to get the ball rolling. All the best

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Note added at 2 hrs (2010-10-20 02:28:38 GMT)
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trying, of course

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Note added at 12 hrs (2010-10-20 12:35:49 GMT)
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sorry, my entry went out twice, first it didn't at all, I think the irregular shape is meant here