Noncalcified Nodules Research Articles

Screening for early lung cancer with low-dose spiral CT: prevalence in 817 asymptomatic smokers.

To present prevalence screening data from a nonrandomized screening trial by using low-dose computed tomography (CT) and a simple algorithm based on the size and attenuation of detected nodules to guide diagnostic work-up. Eight hundred seventeen asymptomatic volunteers (age range, 40-78 years; median age, 53 years; median tobacco consumption, 45 pack-years) underwent spiral low-dose CT of the chest without contrast material enhancement. We regarded all noncalcified pulmonary nodules greater than 10 mm in diameter as potentially malignant and recommended histologic examination or follow-up after 3, 6, 12, and 24 months to exclude growth. For noncalcified pulmonary nodules of 10 mm or smaller, repeat low-dose CT was recommended to exclude growth. In 43% (350 of 817) of individuals, 858 noncalcified pulmonary nodules were found. Thirty-two nodules in 29 subjects were larger than 10 mm. Biopsy of 15 lesions revealed lung cancer in 12 lesions in 11 subjects (prevalence for all ages, 1.3% [11 of 817 subjects]; >50 years of age, 2.1% [11 of 519 subjects]; >60 years of age, 3.9% [eight of 206 subjects]), with a high proportion of early tumor stages (seven tumors, stage I; two, stage II; and three, stage III); three lesions were benign. In 17 nodules larger than 10 mm, follow-up with low-dose CT for a minimum of 24 months did not demonstrate growth. Lung cancer screening with low-dose CT demonstrated a prevalence of asymptomatic cancers in 1.3% of a smoking population, including a high proportion of early tumor stages and a 20% (three of 15) rate of invasive procedures for benign lesions.

The Diagnosis of Small Solitary Pulmonary Nodule: Comparison of Standard and Inverse Digital Images on a High-Resolution Monitor using ROC Analysis

Purpose: To study the impact of inversion of soft-copy chest radiographs on the detection of small solitary pulmonary nodules using a high-resolution monitor. Materials and Methods: The study group consisted of 80 patients who had undergone posterior chest radiography; 40 had a solitary noncalcified pulmonary nodule approximately 1 cm in diameter, and 40 were control subjects. Standard and inverse digital images using the inversion tool on a PACS system were displayed on high-resolution monitors (2048x2560x8 bit). Ten radiologists were requested to rank each image using a five-point scale (1=definitely negative, 3=equivocal or indeterminate, 5=definite nodule), and the data were interpreted using receiver operating characteristic (ROC) analysis. Results: The area under the ROC curve for pooled data of standard image sets was significantly larger than that of inverse image sets (0.8893 and 0.8095, respectively; p 0.05). Conclusion: For detecting small solitary pulmonary nodules, inverse digital images were significantly inferior to standard digital images.

European Institute of Oncology project for lung cancer screening

The opportunity of a screening for lung cancer has been debated for years, since the value of low-dose spiral CT in detecting small parenchymal lesions was demonstrated by ELCAP and other reports. I would like to present to ICIS members the first results of a preliminary study performed in Milan, even though complete data cannot be divulged prior to publication. These results could help in planning further studies or new protocols. The study started in May 2000. 1036 volunteers, over 50 years of age, were enrolled who were either heavy smokers or ex-smokers with a history of more than 1 packet/day for more than 20 years. They have all been submitted to two yearly consecutive low-dose spiral CT chest examination (140 kVp, 40 mA, 2 : 1 pitch, with a slice thickness of 10 mm. Effective dose equivalent to patient was estimated 0.7 mSv). The examined population had a mean age of 58 (range 50–70), 742 males and 297 females, smoking on average 26 cigarettes a day for a mean of 37 years. 14% of volunteers had stopped smoking for a mean of 9 years. After the first low-dose CT, 5.91% of volunteers were recalled for further investigations, as a pulmonary lesion greater than 5 mm was detected. Nodules smaller than 5 mm were not considered for diagnostic work-up: at the second year CT only 1/151 of such nodules showed increased size (from 4.8 to 7.5 mm). This was an adenocarcinoma (T1N0). Out of the 61 recalled subjects, 15 had non-nodular abnormalities and 46 a non-calcified nodular lesion. Diagnostic work-up was performed by HRCT, contrast enhancement evaluation (feasible in 65% of nodules, having positive basal density and homogeneous enhancement), PET (for lesions greater than 7 mm), 3 months’ follow-up with volumetric analysis and biopsy when necessary. With regard to non-nodular lesions, HRCT, PET scan and follow-up (required in 5/15 cases) showed to be the most useful and accurate methods to reach the diagnosis. In one case only a VAT biopsy was performed on a benign lesion (a growing partially solid lesion, positive to PET scan, that proved to be due to post-inflammatory changes due to bronchiectasis). The definitive diagnosis of non-calcified nodules was reached in 58% of cases on the basis of HRCT morphology and evaluation of nodular density (when lower than 0 H.U; considered benign): no benign case was biopsied or subjected to surgery; a false-negative diagnosis was due to a small apical nodule, diagnosed as a scar, but the lesion increased from 8 to 15 mm in diameter at the second year low-dose CT. This was a T1N0 adenocarcinoma. The results of contrast enhancement and PET agreed in 22% of cases, leading to diagnosis: we had two false-positive diagnoses (an intraparenchymal inflammatory node and a MALT lymphoma) and one false-negative (an adenocarcinoma diagnosed 3 months later on the basis of its growth, evaluated at HRCT due to its irregular morphology). Follow-up for evaluation of nodule growth was required to reach a diagnosis in 22% of recalled patients: all the diagnoses, but one, were confirmed by operation (in malignant cases) or by the 1 year follow-up. Only one case of a regular round and smooth 8 mm nodule, with indeterminate contrast enhancement and PET negative, grew from 3.42 to 5.25 mm3 in 6 months and was submitted to VAT biopsy. This was a hamartoma. Only 7% of the recalled patients with benign lesions were submitted to invasive procedures. Preliminary results confirm the ability of low-dose CT to detect small parenchymal lesions. The recall rate is low, considering that only nodules greater than 5 mm are submitted to follow-up, and this seems to be justified by our results. The use of contrast enhancement and PET scan to characterize the lesions reduces the need of follow-up and of invasive procedures.

Computed tomography screening for lung cancer in asbestos-exposed workers

We conducted a computed tomography (CT) screening for lung cancer in a high-risk population. Six hundred and two workers (38–81 years, 97% smokers) with asbestos-related occupational disease were screened using spiral CT and chest radiography. The national cancer registry was checked for possible false negative cases. The screening detected 111 patients with non-calcified nodules >0.5 cm in diameter and 66 of them were referred for further hospital examination. We found five lung cancers (106 false positive cases) with a histological spectrum similar to the national, natural occurrence of the disease (two adeno, one squamous cell, one anaplastic and one metastatic carcinoma) and one peritoneal mesothelioma. Three cases were potentially operable (stage I–II). Unfortunately there was one false negative fine-needle aspiration biopsy (FNAB) with misinterpretation of the follow-up CT scan and another patient who refused further investigations after an inadequate FNAB. In the end only one patient with adenocarcinoma underwent surgery. After 3 years of follow-up two new lung cancers were reported to the cancer registry with no evidence of tumour in the retrospective analysis of the screening CT scan. The sensitivity of CT screening was 100%. CT was capable of detecting early lung cancer in asbestos-exposed patients with a lot of confusing pulmonary and pleural pathology. Due to the high number of positive findings attention should be paid to patient compliance and the follow-up protocols and patient selection in future screening programmes.

Early lung cancer action project: initial findings on repeat screenings.

The Early Lung Cancer Action Project (ELCAP) was designed to evaluate the usefulness of annual computed tomography (CT) screening for lung carcinoma. With the baseline results having been reported previously, the focus of the current study was on the early results of the repeat screenings. A cohort of 1000 high-risk individuals was recruited for baseline and annual repeat CT screening. At last follow-up, a total of 1184 annual repeat screenings had been performed. A positive result from the screening test was defined as newly detected, one to six noncalcified pulmonary nodules with interim growth. The diagnostic workup of the individuals was guided by recommendations supplied by the ELCAP investigators to the collaborating clinicians. Of the 1184 repeat CT screenings, the test result was positive in 30 (2.5%). In 2 of these 30 cases, the individual died (of an unrelated cause) before diagnostic workup and the nodule(s) resolved in another 12 individuals. In the remaining 16 individuals, the absence of further growth was documented by repeat CT in 8 individuals and further growth was documented in the remaining 8 individuals. All eight individuals with further nodular growth underwent biopsy and malignancy was diagnosed in seven. Six of these seven malignancies were nonsmall cell carcinomas (five of which were Stage IA and one of which was Stage IIIA) and the one small cell carcinoma was found to be of limited stage. The median size dimension of these malignancies was 8 mm. In another two subjects, symptoms prompted the interim diagnosis of lung carcinoma. Neither of these malignancies was nodule-associated but rather were endobronchial; one was a Stage IIB nonsmall cell carcinoma and the other was a small cell carcinoma of limited stage. False-positive screening test results are uncommon and usually manageable without biopsy; compared with no screening, such screenings permit diagnosis at substantially earlier and thus more curable stages. Annual repetition of CT screening is sufficient to minimize symptom-prompted interim diagnoses of nodule-associated malignancies.

Should screening for lung cancer be revisited?

J Thorac Cardiovasc Surg 2001;121:1031-2

Pulmonary metastases at diagnosis of neuroblastoma in pediatric patients: CT findings and prognosis.

We undertook this study to determine the frequency, CT appearance, and clinical implications of the rare occurrence of pulmonary metastases among children presenting with neuroblastoma. A search of the Children's Cancer Group database revealed 21 of 567 children with reported lung metastases at original diagnosis of neuroblastoma. CT examinations available for 17 of these patients were analyzed retrospectively to determine if lung metastases were present, and if so, to characterize their radiographic features. Seventeen (3%) of 567 patients presenting with Evans stage IV neuroblastoma had confirmed pulmonary metastases at diagnosis. All had metastases to at least one site other than the lungs. The most common CT appearance of pulmonary lesions was of up to five, small, bilateral, noncalcified nodules. In nine patients (53%), the pulmonary nodules initially resolved with treatment. In this cohort, six children developed progressive disease and died, and three are still alive. All eight children whose lung lesion did not completely respond to treatment died. Overall, children with pulmonary metastases had unfavorable Shimada histology, a higher association with amplification of the MYCN oncogene (p = 0.0002), and a decreased event-free survival (p < 0.001) when compared with all children with stage IV neuroblastoma without pulmonary metastases. The search for neuroblastoma lung metastases, which occur more frequently than previously reported, is clinically important because their presence portends a poor prognosis.

The solitary pulmonary nodule on chest radiography: can we really tell if the nodule is calcified?

This study was designed to assess the ability of radiologists to accurately detect calcification within a solitary pulmonary nodule with chest radiography. Thirty-five solitary pulmonary nodules that were examined by both posteroanterior and lateral chest radiography and on thin-section CT were retrospectively identified. Fourteen radiologists blinded to the results of CT assessed the nodules for the presence or absence of calcification using chest radiographs alone. The radiologists then assigned one of six values on the basis of their confidence in that assessment. The accuracy and confidence values for each nodule were analyzed on the basis of the presence or absence of calcification as seen on CT. Receiver operating characteristic (ROC) curves were generated. The positive predictive value of a "definitely calcified" assessment was 0.93. Combining all levels of radiologists' confidence, the sensitivity of the chest radiograph in the detection of calcium was 0.50 and the specificity was 0.87. There was no difference in the confidence levels reported between the calcified and noncalcified nodules, and there was no correlation of nodule size with accuracy or confidence level. The ability of radiologists to detect calcium in a solitary pulmonary nodule by chest radiography was low, as defined by the ROC data. Of the "definitely calcified" nodules, up to 7% may not be calcified and may be potentially malignant. Without documentation of long-term stability, a low threshold for recommending CT may be appropriate.

Early lung cancer action project

BACKGROUND The Early Lung Cancer Action Project (ELCAP) was designed to evaluate the usefulness of annual computed tomography (CT) screening for lung carcinoma. With the baseline results having been reported previously, the focus of the current study was on the early results of the repeat screenings. METHODS A cohort of 1000 high-risk individuals was recruited for baseline and annual repeat CT screening. At last follow-up, a total of 1184 annual repeat screenings had been performed. A positive result from the screening test was defined as newly detected, one to six noncalcified pulmonary nodules with interim growth. The diagnostic workup of the individuals was guided by recommendations supplied by the ELCAP investigators to the collaborating clinicians. RESULTS Of the 1184 repeat CT screenings, the test result was positive in 30 (2.5%). In 2 of these 30 cases, the individual died (of an unrelated cause) before diagnostic workup and the nodule(s) resolved in another 12 individuals. In the remaining 16 individuals, the absence of further growth was documented by repeat CT in 8 individuals and further growth was documented in the remaining 8 individuals. All eight individuals with further nodular growth underwent biopsy and malignancy was diagnosed in seven. Six of these seven malignancies were nonsmall cell carcinomas (five of which were Stage IA and one of which was Stage IIIA) and the one small cell carcinoma was found to be of limited stage. The median size dimension of these malignancies was 8 mm. In another two subjects, symptoms prompted the interim diagnosis of lung carcinoma. Neither of these malignancies was nodule-associated but rather were endobronchial; one was a Stage IIB nonsmall cell carcinoma and the other was a small cell carcinoma of limited stage. CONCLUSIONS False-positive screening test results are uncommon and usually manageable without biopsy; compared with no screening, such screenings permit diagnosis at substantially earlier and thus more curable stages. Annual repetition of CT screening is sufficient to minimize symptom-prompted interim diagnoses of nodule-associated malignancies. Cancer 2001;92:153–9. © 2001 American Cancer Society.

Relative risk of cancer in sonographically detected thyroid nodules with calcifications

Purpose The aim of this prospective study was to evaluate the significance of sonographically detected thyroid calcifications in the diagnosis of thyroid cancer. Methods One hundred eighty-eight patients with thyroid disease, including 37 with thyroid cancer, were included in the study. Each patient underwent preoperative, high-resolution sonography to evaluate the thyroid gland for the presence of calcifications. Results The highest incidence of calcification was found in thyroid cancer (54%), followed by multinodular goiter (40%), solitary nodular goiter (14%), and follicular adenomas (12%). The incidence of cancer was significantly higher in calcified nodules (29%) than in noncalcified nodules in the entire group (14%) (p = 0.019), with a relative risk of 2.5. In the group of solitary thyroid nodules, the incidence of cancer in the calcified nodules (55%) was higher than in the nodules without calcification (23%) (p = 0.016). Multiple noncalcified thyroid nodules harbored cancer in only 5% of cases. Compared with multiple noncalcified thyroid nodules, the solitary calcified nodules demonstrated a relative risk of 22.8. In both the solitary and multiple nodules, the relative risk in the presence of calcification was about the same, around 4. Patients younger than 40 years with calcified nodules constituted a high-risk group, with a relative risk of 3.8 versus 2.5 in patients older than 40 years with calcified nodules. Conclusions The detection of thyroid calcifications by sonography is diagnostically valuable, especially in cases involving a solitary nodule or a young person. The presence of calcifications in these cases should raise the suspicion of malignancy. The low incidence of cancer in patients with multiple noncalcified thyroid nodules suggests that a more conservative approach may be appropriate in such cases. © 2000 John Wiley & Sons, Inc. J Clin Ultrasound 28:347–352, 2000.

Small Nodules Detected on Chest Radiography: Does Size Predict Calcification?

To determine whether the likelihood of lung nodule calcification can be predicted from nodule size as measured on a chest radiograph (CXR). Retrospective review of CXRs of patients with lung nodules < or =1 cm in size detected on CT scanning. CT images were used to identify calcifications and to provide spatial localization for readers to visualize nodules on a CXR and to measure their size. A subset of these nodules then was reexamined by different readers who did not view the CT scans Two university hospitals (Albuquerque, NM; Dallas, TX) and a US Air Force/Veterans Administration medical center (Albuquerque, NM). Two hundred thirty-six nodules in 185 patients One half of the nodules (118) seen on CT scans could not be located on CXR, of which 8 (7%) were calcified. The prevalence of calcifications in the other 118 nodules visualized on CXRs was much higher (71 of 118 nodules [60%]; p<0.005). Among the nodules visualized on CXRs, those < 7 mm in diameter (44 of 57 nodules [77%]) were more likely to be calcified than those > or = 7 mm in diameter (27 of 61 nodules [44%]; p<0.005). Radiographs of 42 of the smallest nodules visualized on CXRs by the initial readers later were examined prospectively by different readers who did not have access to the CT images. Thirty of 33 of the calcified nodules (91%) but only 3 of 9 of the noncalcified nodules (33%) were detected (p<0.005). These readers also recorded 40 additional small nodules that were not seen on CT scans, which were considered to be false-positives. Nodules detected on CXRs that measure <7 mm in size are likely to be calcified or to represent a false-positive finding.

Detection of early lung cancer.

Background. The Early Lung Cancer Action Project (ELCAP) is designed to evaluate baseline and annual repeat screening by low-radiation-dose computed tomography (low-dose CT) in people at high risk of lung cancer. We report the baseline experience. Methods. ELCAP has enrolled 1000 symptom-free volunteers, aged 60 years or older, with at least 10 pack-years of cigarette smoking and no previous cancer, who were medically fit to undergo thoracic surgery. After a structured interview and informed consent, chest radiographs and low-dose CT were done for each participant. The diagnostic investigation of screen-detected non-calcified pulmonary nodules was guided by ELCAP recommendations, which included short-term high-resolution CT follow-up for the smallest non-calcified nodules. Findings. Noncalcified nodules were detected in 233 (23% [95% CI 21–26]) participants by low-dose CT at baseline, compared with 68 (7% [5–9]) by chest radiography. Malignant disease was detected in 27 (2.7% [1.8–3.8]) by CT and seven (0.7% [0.3–1.3]) by chest radiography, and stage I malignant disease in 23 (2.3% [1.5–3.3]) and four (0.4% [0.1–0.9]), respectively. Of the 27 CT-detected cancers, 26 were resectable. Biopsies were done on 28 of the 233 participants with non-calcified nodules; 27 had malignant noncalcified nodules and one had a benign nodule. Another three individuals underwent biopsy against the ELCAP recommendations; all had benign non-calcified nodules. No participant had thoracotomy for a benign nodule. Interpretation. Low-dose CT can greatly improve the likelihood of detection of small non-calcified nodules, and thus of lung cancer at an earlier and potentially more curable stage. Although false-positive CT results are common, they can be managed with little use of invasive diagnostic procedures. (Lancet 1999;354:99–105)

Calcified Left Ventricular Mass: Unusual Clinical, Echocardiographic, and Computed Tomographic Findings of Primary Cardiac Osteosarcoma

Calcified Left Ventricular Mass: Unusual Clinical, Echocardiographic, and Computed Tomographic Findings of Primary Cardiac Osteosarcoma

Relative risk of cancer in sonographically detected thyroid nodules with calcifications.

The aim of this prospective study was to evaluate the significance of sonographically detected thyroid calcifications in the diagnosis of thyroid cancer. One hundred eighty-eight patients with thyroid disease, including 37 with thyroid cancer, were included in the study. Each patient underwent preoperative, high-resolution sonography to evaluate the thyroid gland for the presence of calcifications. The highest incidence of calcification was found in thyroid cancer (54%), followed by multinodular goiter (40%), solitary nodular goiter (14%), and follicular adenomas (12%). The incidence of cancer was significantly higher in calcified nodules (29%) than in noncalcified nodules in the entire group (14%) (p = 0.019), with a relative risk of 2.5. In the group of solitary thyroid nodules, the incidence of cancer in the calcified nodules (55%) was higher than in the nodules without calcification (23%) (p = 0.016). Multiple noncalcified thyroid nodules harbored cancer in only 5% of cases. Compared with multiple noncalcified thyroid nodules, the solitary calcified nodules demonstrated a relative risk of 22.8. In both the solitary and multiple nodules, the relative risk in the presence of calcification was about the same, around 4. Patients younger than 40 years with calcified nodules constituted a high-risk group, with a relative risk of 3.8 versus 2.5 in patients older than 40 years with calcified nodules. The detection of thyroid calcifications by sonography is diagnostically valuable, especially in cases involving a solitary nodule or a young person. The presence of calcifications in these cases should raise the suspicion of malignancy. The low incidence of cancer in patients with multiple noncalcified thyroid nodules suggests that a more conservative approach may be appropriate in such cases.

Early Lung Cancer Action Project: overall design and findings from baseline screening

The Early Lung Cancer Action Project (ELCAP) is designed to evaluate baseline and annual repeat screening by low-radiation-dose computed tomography (low-dose CT) in people at high risk of lung cancer. We report the baseline experience. ELCAP has enrolled 1000 symptom-free volunteers, aged 60 years or older, with at least 10 pack-years of cigarette smoking and no previous cancer, who were medically fit to undergo thoracic surgery. After a structured interview and informed consent, chest radiographs and low-dose CT were done for each participant. The diagnostic investigation of screen-detected non-calcified pulmonary nodules was guided by ELCAP recommendations, which included short-term high-resolution CT follow-up for the smallest non-calcified nodules. Non-calcified nodules were detected in 233 (23% [95% CI 21-26]) participants by low-dose CT at baseline, compared with 68 (7% [5-9]) by chest radiography. Malignant disease was detected in 27 (2.7% [1.8-3.8]) by CT and seven (0.7% [0.3-1.3]) by chest radiography, and stage I malignant disease in 23 (2.3% [1.5-3.3]) and four (0.4% [0.1-0.9]), respectively. Of the 27 CT-detected cancers, 26 were resectable. Biopsies were done on 28 of the 233 participants with non-calcified nodules; 27 had malignant non-calcified nodules and one had a benign nodule. Another three individuals underwent biopsy against the ELCAP recommendations; all had benign non-calcified nodules. No participant had thoracotomy for a benign nodule. Low-dose CT can greatly improve the likelihood of detection of small non-calcified nodules, and thus of lung cancer at an earlier and potentially more curable stage. Although false-positive CT results are common, they can be managed with little use of invasive diagnostic procedures.

Detection failures in spiral CT screening for lung cancer: analysis of CT findings.

To clarify the computed tomographic (CT) findings and the progression of minute lung cancers that were missed at initial spiral CT screening but were later detected. The findings from seven patients with lung cancer that was missed at the initial spiral CT screening were reviewed. Retrospective CT findings, time to detection, cell type, and pathologic stage were evaluated. Minute lung cancers missed at early spiral CT included a nodule among the shadows of old tuberculosis (n = 2), a faint nodule with high attenuation in the center of the nodule (n = 1), an increase in attenuation just adjacent to an axial peripheral pulmonary vessel (n = 1) and adjacent to a craniocaudal peripheral pulmonary vessel (n = 1), and a minute faint nodule (n = 2). The time to detection ranged from 6 to 18 months. At pathologic examination, six cancers were stage I, and one was stage II. Minute nodules of lung cancer that are near the threshold of detectability may be missed at spiral CT screening. It is important to examine noncalcified nodules with thin-section CT even when lesions from prior disease, such as those from old tuberculosis, exist and to evaluate the shadows of pulmonary vessels carefully. A follow-up examination is highly recommended.

Human Pulmonary Dirofilariasis: Analysis of 24 Cases From Sao Paulo, Brazil

To present the clinical, radiologic, and pathologic aspects of 24 cases of human pulmonary dirofilariasis (HPD) from São Paulo, Brazil. Retrospective study of 24 patients with a confirmed diagnosis of HPD over a 14-year period (from February 1982 to June 1996). Thoracic Surgery and Pulmonary Division, University of São Paulo and Hospital Albert Einstein, São Paulo, Brazil. Seventeen patients were male (70.1%) and seven were female (29.9%). Their mean age was 51.4 years. Fifty-four percent of the patients were asymptomatic and 75% had a well-circumscribed noncalcified peripheral subpleural pulmonary nodule on the chest radiograph and thoracic CT scan, located preferentially in the lower lobes. The diagnosis was made after thoracotomy and wedge resections in 16 patients, by videothoracoscopy in six, after a pleural biopsy in one, and after necropsy in one. The pathologic examination of all the nodules revealed a central zone of necrosis, surrounded by a narrow granulomatous zone and peripherally by fibrous tissue. Pulmonary vessels exhibit varying degrees of endarteritis. In all cases, a dead worm, usually necrotic and fragmented, was found. A subpleural, noncalcified pulmonary nodule in the appropriate clinical and epidemiologic setting should alert the clinician, radiologist, or pathologist to the possibility of Dirofilaria. HPD should be considered in the differential diagnosis of pulmonary nodules.

Clinical outcome of doubtful mammographic findings.

We performed this study to determine whether subthreshold findings of malignancy can be detected prospectively during interpretation of routine mammographic screenings. For several years we have marked with crayon mammographic findings identified at screening that may represent precursor lesions but that we judge so likely to be benign that further workup is not indicated. The crayon marks prompt a closer look at the designated area on the next screening examination. We reviewed all screening examinations performed between August 1991 and October 1992 for which we had done prior normal screening. The prior mammograms were examined for crayon marks that indicated possible precursor lesions, and outcome was assessed on the basis of findings of subsequent screenings. Crayon marks of 543 findings (382 women) were identified on prior normal examinations in the 5514 cases reviewed. Marked findings consisted of calcifications (48%), noncalcified nodules (22%), vague densities (18%), asymmetries (7%), combination findings (2%), and possible architectural distortions (2%). On subsequent examination (mean interval, 30 months; range, 231 days to 90 months), 74% of marked findings showed no significant change, 21% were less apparent or had disappeared, 4% were slightly more apparent but still within normal limits, and six cases (1%) were interpreted as abnormal, which resulted in diagnostic workup. Three of the six latter cases were judged to be benign after further imaging evaluation; the other three patients underwent biopsy. One of these cases resulted in a diagnosis of low-grade ductal carcinoma in situ; the other two findings were benign. No unsuspected cancers were found after linkage with our tumor registry 1 year after the most recent examination with crayon marks. This study shows that almost all prospectively marked benign-appearing findings are benign and inconsequential. The medicolegal implications of this observation include the inappropriateness of malpractice claims in cases in which cancer could not reasonably be detected prospectively.

The effects of lossy compression on the detection of subtle pulmonary nodules

We examined the ability of radiologists to detect pulmonary nodules in computed radiographic (CR) chest images subjected to lossy image compression. Low-contrast 1-cm diameter targets simulating noncalcified pulmonary nodules were introduced into clinical images and presented to ten radiologists in a series of two-alternative forced-choice (2AFC) observer experiments. The percentages of correct observer responses obtained while viewing noncompressed images (1:1) were compared with those obtained for the same images compressed 7:1, 16:1, 44:1, and 127:1. The images were compressed using a standard full-frame discrete cosine transform (DCT) technique. The degree of compression was determined by quantizing Fourier components in various frequency channels and then Huffman encoding the result. The data show a measurable decline in performance for each compression ratio. Through signal-to-noise ratio (SNR) analysis, we found that the reduction in performance was due primarily to the compression algorithm that increased image noise in the frequency channels of the signals to be detected.

A patient with a resectable left-upper-lobe lung cancer has an 8 mm contralateral noncalcified lung nodule.

A patient with a resectable left-upper-lobe lung cancer has an 8 mm contralateral noncalcified lung nodule.