Exploring Liability Issues in Radiology -- Section 1

EXPLORING LIABILITY ISSUES IN RADIOLOGY Section 1

Numerous research studies reported over the past

50 years disclose an average “miss rate” of 30 percent in the

retrospective evaluation of general radiographic, CT, MRI, and

ultrasound examinations.1 What this means is that if 100

radiologic examinations containing abnormal findings are

shown to radiologists, an average of 30 percent of the

abnormalities will be missed. Such studies, however, do not

reflect the everyday practice of radiology, in which the

number of normal examinations far exceeds the number of

those that are abnormal. Performance improvement data

derived from radiologists’ interpretations, under ordinary

working conditions, of both

RADIOLOGIC ERRORS AND THEIR CAUSES

normal and abnormal radiologic studies disclose an average

error rate of 3 to 4 percent.2 Fortunately, most of those

errors either do not cause injury to patients or are corrected

by review of radiologic studies before they become

injurious.3

Of missed radiological diagnoses, 70 percent are perceptual

in nature—that is, the radiologist fails to “see” the

abnormality.4 The remaining 30 are cognitive errors—the

radiologist “sees” an abnormality but attaches the wrong

significance to what is seen, through either lack of

knowledge or lack of judgment.

Average “miss rate” in general radiographic, CT, MRI, and ultrasound examinations

Average error rate of both normal and abnormal radiological studies

Percentage of missed radiological diagnoses that are perceptual in nature

Numerous research studies reported over the past

50 years disclose an average “miss rate” of 30 percent in the

retrospective evaluation of general radiographic, CT, MRI, and

ultrasound examinations.1 What this means is that if 100

radiologic examinations containing abnormal findings are

shown to radiologists, an average of 30 percent of the

abnormalities will be missed. Such studies, however, do not

reflect the everyday practice of radiology, in which the

number of normal examinations far exceeds the number of

those that are abnormal. Performance improvement data

derived from radiologists’ interpretations, under ordinary

working conditions, of both

RADIOLOGIC ERRORS AND THEIR CAUSES

normal and abnormal radiologic studies disclose an average

error rate of 3 to 4 percent.2 Fortunately, most of those

errors either do not cause injury to patients or are corrected

by review of radiologic studies before they become

injurious.3

Of missed radiological diagnoses, 70 percent are perceptual

in nature—that is, the radiologist fails to “see” the

abnormality.4 The remaining 30 are cognitive errors—the

radiologist “sees” an abnormality but attaches the wrong

significance to what is seen, through either lack of

knowledge or lack of judgment.

Average “miss rate” in general radiographic, CT, MRI, and ultrasound examinations

Average error rate of both normal and abnormal radiological studies

Percentage of missed radiological diagnoses that are perceptual in nature

Some diagnostic errors are caused by “satisfaction of search.”

This is a phenomenon that occurs when an imaging study

contains several abnormalities; the radiologist notes one or

perhaps two of them, but then tends to stop looking for

additional abnormalities. In other words, his or her search

has been “satisfied” prematurely.

Another cause of errors is the alliterative error or “diagnosis

momentum,” in which the radiologist looks at a previous

study or report rendered by the same or another radiologist

before interpreting the new follow-up study, and if the

previous diagnosis was erroneous, the radiologist

interpreting the new study has a tendency to repeat the

same error.

‘Satisfaction of Search’

Diagnosis Momentum

RISK MANAGEMENT RECOMMENDATIONS

• Poor image quality increases the likelihood of missing an

abnormality. Patient positioning and radiographic exposure

must be adequate before interpretation.

• Radiologists should have as much patient information as

possible, along with previous radiologic examinations and

reports for comparison, before rendering the final

interpretation.

• When interpreting follow-up studies, radiologists should

always consider whether the findings could represent

anything different from the previously suggested diagnosis.

• If asked by a referring physician what was found on the

radiologic examination of the patient, radiologists should

consider answering as follows: “I interpreted the study as

normal (or as showing specific pathology), but let’s look at

it again together” (if physician is present), or “Let me look

at it again” (if physician is not present). Studies have shown

that radiologists interpreting the same images at different

times disagree with themselves as much as 20 percent of

the time, and thus a second look can reveal a finding that

was initially overlooked or misinterpreted.5

Perceptual

Figure 1

Some diagnostic errors are caused by “satisfaction of search.”

This is a phenomenon that occurs when an imaging study

contains several abnormalities; the radiologist notes one or

perhaps two of them, but then tends to stop looking for

additional abnormalities. In other words, his or her search

has been “satisfied” prematurely.

Another cause of errors is the alliterative error or “diagnosis

momentum,” in which the radiologist looks at a previous

study or report rendered by the same or another radiologist

before interpreting the new follow-up study, and if the

previous diagnosis was erroneous, the radiologist

interpreting the new study has a tendency to repeat the

same error.

‘Satisfaction of Search’

Diagnosis Momentum

RISK MANAGEMENT RECOMMENDATIONS

• Poor image quality increases the likelihood of missing an

abnormality. Patient positioning and radiographic exposure

must be adequate before interpretation.

• Radiologists should have as much patient information as

possible, along with previous radiologic examinations and

reports for comparison, before rendering the final

interpretation.

• When interpreting follow-up studies, radiologists should

always consider whether the findings could represent

anything different from the previously suggested diagnosis.

• If asked by a referring physician what was found on the

radiologic examination of the patient, radiologists should

consider answering as follows: “I interpreted the study as

normal (or as showing specific pathology), but let’s look at

it again together” (if physician is present), or “Let me look

at it again” (if physician is not present). Studies have shown

that radiologists interpreting the same images at different

times disagree with themselves as much as 20 percent of

the time, and thus a second look can reveal a finding that

was initially overlooked or misinterpreted.5

Perceptual

Figure 1

• Occasionally the patient’s physical condition or other

circumstances preclude obtaining all required views or

using optimal exposure techniques. If the clinical situation

requires the interpretation of less than optimal studies,

radiologists should state in the report that the examination

was incomplete because of the patient’s condition and that

additional or follow-up views need to be obtained when

the patient’s condition permits.

• Radiologists should not hesitate to consult with radiology

colleagues for second opinions or with referring physicians

for additional patient information before rendering final

reports.

• Additional or follow-up studies should be recommended

when indicated.

• Making instant or rapid diagnoses may be acceptable in

film-interpreting conferences at medical meetings, but

doing so in everyday practice may result in limiting

diagnostic possibilities and may increase the likelihood of

error. Taking sufficient time during radiologic interpretation

for deliberation and reflection is essential for good

judgment.

Defending the Missed Diagnosis

Defending a radiologist who missed a radiologic finding is

difficult. Two biases work against the defendant radiologist:

(a) hindsight bias (the tendency for people with knowledge of

the actual outcome of an event to believe falsely that they

would have predicted the outcome), and (b) outcome bias

(the tendency for people to attribute blame more readily

when the outcome of an event is serious than when the

outcome is comparatively minor). In other words, once a

radiologic diagnosis is established, often by follow-up

radiologic studies, it is easy to look back at an earlier study

that had been misread and believe that the abnormality was

evident.

Furthermore, if the missed diagnosis

was not clinically significant, such as a

rib fracture, later observers are more

inclined to excuse the radiologist’s

error. However, if the radiologist missed a clinically significant

condition such as a fracture or dislocation of the spine leading

to paralysis, even if the finding was extremely subtle and

occult, later observers are more likely to find the radiologist

negligent.

Although it is difficult to defend a radiologist who has failed

• Occasionally the patient’s physical condition or other

circumstances preclude obtaining all required views or

using optimal exposure techniques. If the clinical situation

requires the interpretation of less than optimal studies,

radiologists should state in the report that the examination

was incomplete because of the patient’s condition and that

additional or follow-up views need to be obtained when

the patient’s condition permits.

• Radiologists should not hesitate to consult with radiology

colleagues for second opinions or with referring physicians

for additional patient information before rendering final

reports.

• Additional or follow-up studies should be recommended

when indicated.

• Making instant or rapid diagnoses may be acceptable in

film-interpreting conferences at medical meetings, but

doing so in everyday practice may result in limiting

diagnostic possibilities and may increase the likelihood of

error. Taking sufficient time during radiologic interpretation

for deliberation and reflection is essential for good

judgment.

Defending the Missed Diagnosis

Defending a radiologist who missed a radiologic finding is

difficult. Two biases work against the defendant radiologist:

(a) hindsight bias (the tendency for people with knowledge of

the actual outcome of an event to believe falsely that they

would have predicted the outcome), and (b) outcome bias

(the tendency for people to attribute blame more readily

when the outcome of an event is serious than when the

outcome is comparatively minor). In other words, once a

radiologic diagnosis is established, often by follow-up

radiologic studies, it is easy to look back at an earlier study

that had been misread and believe that the abnormality was

evident.

Furthermore, if the missed diagnosis

was not clinically significant, such as a

rib fracture, later observers are more

inclined to excuse the radiologist’s

error. However, if the radiologist missed a clinically significant

condition such as a fracture or dislocation of the spine leading

to paralysis, even if the finding was extremely subtle and

occult, later observers are more likely to find the radiologist

negligent.

Although it is difficult to defend a radiologist who has failed

to find a radiologic abnormality that, in retrospect, can be

readily perceived, solid supporting data are available that can

assist in the radiologist’s defense. These data include

statistics on the frequency of errors committed by radiologists

and other physicians during the course of an ordinary

practice, the factors that cause varying conspicuity of

radiographic densities, limitations of normal human visual

perception, and evidence that the process by which the

radiologist originally rendered the interpretation was free of

carelessness.

* * * *

RADIATION ONCOLOGY

With recent advances in diagnostic imaging and

radiotherapy treatment and delivery, imaging is integral in

the-day-to-day practice of radiation oncology. Radiation

oncologists often must make targeting decisions that will

have profound effects on the efficacy of the therapy. If an

area at risk is not covered by radiotherapy, underdosing may

result, which can lead to disease recurrence and avoidable

death. On the other hand, increasing the radiotherapy target

is associated with increased normal tissue effects, which can

lead to avoidable toxicity. Diagnostic radiologists are often

consulted by radiation oncologists to assist in this critical

process. The process of target delineation is often tedious

and involves correlating multiple imaging sets and diagnostic

and clinical information. It is imperative that when a

to find a radiologic abnormality that, in retrospect, can be

readily perceived, solid supporting data are available that can

assist in the radiologist’s defense. These data include

statistics on the frequency of errors committed by radiologists

and other physicians during the course of an ordinary

practice, the factors that cause varying conspicuity of

radiographic densities, limitations of normal human visual

perception, and evidence that the process by which the

radiologist originally rendered the interpretation was free of

carelessness.

* * * *

RADIATION ONCOLOGY

With recent advances in diagnostic imaging and

radiotherapy treatment and delivery, imaging is integral in

the-day-to-day practice of radiation oncology. Radiation

oncologists often must make targeting decisions that will

have profound effects on the efficacy of the therapy. If an

area at risk is not covered by radiotherapy, underdosing may

result, which can lead to disease recurrence and avoidable

death. On the other hand, increasing the radiotherapy target

is associated with increased normal tissue effects, which can

lead to avoidable toxicity. Diagnostic radiologists are often

consulted by radiation oncologists to assist in this critical

process. The process of target delineation is often tedious

and involves correlating multiple imaging sets and diagnostic

and clinical information. It is imperative that when a

treatment planning image is reviewed, a diagnostic

radiologist should be consulted to ensure appropriate

targeting.

Radiation therapy is associated with toxicity. Unfortunately,

the interpretation of images by diagnostic radiologists can

inappropriately characterize changes due to radiation as

“radiation enteritis” or “radiation pneumonitis.” These

diagnoses should not be made on the basis of imaging. For

example, radiation pneumonitisis a distinct clinical entity

encompassing radiographic changes, shortness of breath, dry

cough and fever in patients who receive thoracic

radiotherapy. Any person who receives thoracic radiotherapy

will have significant imaging changes that may have limited or

no clinical implications. Proper wording of a diagnostic

imaging report is critical from both medical and legal

standpoints.

Proper wording of a diagnostic imaging report is critical from both medical and legal standpoints.

From a medicolegal standpoint, probably even more

damaging and inaccurate than interpretation of imaging with

an inappropriate clinical diagnosis is the improper

assignment of imaging changes to radiotherapy.

Radiotherapy toxicity is defined as effects directly

attributable to radiotherapy or any adverse events after

radiotherapy. When evaluating patients for toxicity after

radiotherapy, clinicians often conclude that the effect is due

to the radiotherapy alone, potentially leading to a mistaken

diagnosis. For example, if a patient has had concurrent

chemotherapy or

previous surgeries, the

only term that should be

used in the diagnostic

radiologic report is

“consistent with treatment effects.” It is

incorrect, and presents liability

implications, to attribute a treatment

effect to radiation if other potentially

toxic therapies have been delivered. Patients and referring

physicians can jump to inaccurate and unfounded conclusions

from incorrectly interpreted images and incorrectly worded

diagnostic reports.

treatment planning image is reviewed, a diagnostic

radiologist should be consulted to ensure appropriate

targeting.

Radiation therapy is associated with toxicity. Unfortunately,

the interpretation of images by diagnostic radiologists can

inappropriately characterize changes due to radiation as

“radiation enteritis” or “radiation pneumonitis.” These

diagnoses should not be made on the basis of imaging. For

example, radiation pneumonitisis a distinct clinical entity

encompassing radiographic changes, shortness of breath, dry

cough and fever in patients who receive thoracic

radiotherapy. Any person who receives thoracic radiotherapy

will have significant imaging changes that may have limited or

no clinical implications. Proper wording of a diagnostic

imaging report is critical from both medical and legal

standpoints.

Proper wording of a diagnostic imaging report is critical from both medical and legal standpoints.

From a medicolegal standpoint, probably even more

damaging and inaccurate than interpretation of imaging with

an inappropriate clinical diagnosis is the improper

assignment of imaging changes to radiotherapy.

Radiotherapy toxicity is defined as effects directly

attributable to radiotherapy or any adverse events after

radiotherapy. When evaluating patients for toxicity after

radiotherapy, clinicians often conclude that the effect is due

to the radiotherapy alone, potentially leading to a mistaken

diagnosis. For example, if a patient has had concurrent

chemotherapy or

previous surgeries, the

only term that should be

used in the diagnostic

radiologic report is

“consistent with treatment effects.” It is

incorrect, and presents liability

implications, to attribute a treatment

effect to radiation if other potentially

toxic therapies have been delivered. Patients and referring

physicians can jump to inaccurate and unfounded conclusions

from incorrectly interpreted images and incorrectly worded

diagnostic reports.

• Inaccurate definition of a radiotherapy target can lead to

avoidable toxicity and/or disease recurrence.

• Regarding patients who have undergone or are undergoing

radiotherapy, using terms in the diagnostic report that

imply a clinical diagnosis should be avoided unless there is

other supporting evidence.

* * * *

RISK MANAGEMENT RECOMMENDATIONS

DIAGNOSTIC ULTRASOUND

Developed nearly 60 years ago, diagnostic ultrasound is

considered a very safe procedure, with few associated risks or

side effects if properly performed using appropriate

frequency and intensity ranges.

Although claims lodged against radiologists alleging

misdiagnosis of ultrasound examinations are relatively

infrequent, they can be costly.

An important consideration to keep in mind is the fact that

radiologic technologists must be accredited by the Illinois

Emergency Management Agency. The law applies to medical

radiographers, nuclear medicine technologists, radiation

therapy technologists, chiropractic radiographers, limited

diagnostic radiographers, and radiologist assistants.6

• Inaccurate definition of a radiotherapy target can lead to

avoidable toxicity and/or disease recurrence.

• Regarding patients who have undergone or are undergoing

radiotherapy, using terms in the diagnostic report that

imply a clinical diagnosis should be avoided unless there is

other supporting evidence.

* * * *

RISK MANAGEMENT RECOMMENDATIONS

DIAGNOSTIC ULTRASOUND

Developed nearly 60 years ago, diagnostic ultrasound is

considered a very safe procedure, with few associated risks or

side effects if properly performed using appropriate

frequency and intensity ranges.

Although claims lodged against radiologists alleging

misdiagnosis of ultrasound examinations are relatively

infrequent, they can be costly.

An important consideration to keep in mind is the fact that

radiologic technologists must be accredited by the Illinois

Emergency Management Agency. The law applies to medical

radiographers, nuclear medicine technologists, radiation

therapy technologists, chiropractic radiographers, limited

diagnostic radiographers, and radiologist assistants.6

(According to this law, a radiographer is a person other than a

licensed practitioner who applies x-radiation to the human

body while under the general supervision of a licensed

practitioner.) Civil penalties are assessed against

technologists who perform medical radiation procedures

without proper accreditation, and the penalties can be

severe.

RISK MANAGEMENT RECOMMENDATIONS

• The imaging facility and its equipment should be

accredited by the ACR.

• Technologists should be certified by the American Registry

for Diagnostic Medical Sonography.

• Established protocols created by one’s own facility as well

as those published by the ACR should always be followed.

• Only those studies the radiologist is trained and competent

to perform should be undertaken.

• Significant unexpected abnormalities should be reported

to referring physicians in a manner that gives reasonable

assurance of receipt. Such communications should be

documented.

• If the ultrasound exam is recommended by or based on a

follow-up of another imaging study, the original study

should also be reviewed. Proper transducers should be

used. Breasts and small body parts need to be performed

with high-frequency transducers of at least 10 megahertz;

failure to do so may be considered a deviation from the

standard of care. A study performed with an inappropriate

transducer should be redone with proper equipment.

• Proper transducers should be

used. Breasts and small body

parts need to be

performed with high-

frequency transducers of

at least 10 megahertz; failure to do so may be considered a

deviation from the standard of care. A study performed with

an inappropriate transducer should be redone with proper

equipment.

• Whenever possible, radiologists should be involved in

performing sonographic examinations and should not rely

on technologists to interpret findings. The radiologist, not

the technologist or the facility, is ultimately responsible for

ensuring the quality and accuracy of the sonogram.

(According to this law, a radiographer is a person other than a

licensed practitioner who applies x-radiation to the human

body while under the general supervision of a licensed

practitioner.) Civil penalties are assessed against

technologists who perform medical radiation procedures

without proper accreditation, and the penalties can be

severe.

RISK MANAGEMENT RECOMMENDATIONS

• The imaging facility and its equipment should be

accredited by the ACR.

• Technologists should be certified by the American Registry

for Diagnostic Medical Sonography.

• Established protocols created by one’s own facility as well

as those published by the ACR should always be followed.

• Only those studies the radiologist is trained and competent

to perform should be undertaken.

• Significant unexpected abnormalities should be reported

to referring physicians in a manner that gives reasonable

assurance of receipt. Such communications should be

documented.

• If the ultrasound exam is recommended by or based on a

follow-up of another imaging study, the original study

should also be reviewed. Proper transducers should be

used. Breasts and small body parts need to be performed

with high-frequency transducers of at least 10 megahertz;

failure to do so may be considered a deviation from the

standard of care. A study performed with an inappropriate

transducer should be redone with proper equipment.

• Proper transducers should be

used. Breasts and small body

parts need to be

performed with high-

frequency transducers of

at least 10 megahertz; failure to do so may be considered a

deviation from the standard of care. A study performed with

an inappropriate transducer should be redone with proper

equipment.

• Whenever possible, radiologists should be involved in

performing sonographic examinations and should not rely

on technologists to interpret findings. The radiologist, not

the technologist or the facility, is ultimately responsible for

ensuring the quality and accuracy of the sonogram.

• Radiologists are not required to be present at every

ultrasound exam, but if any question or doubt arises

regarding a scan performed by an ultrasound technologist,

the radiologist should participate in the scanning process.

• Any limitation to the study that compromises the

interpretation, such as bowel gas, patient motion, etc.,

should be reported.

Claims involving obstetrical ultrasound in particular can be

quite costly due to the involvement of infants with potentially

lifelong disabilities or death.

RISK MANAGEMENT RECOMMENDATIONS

• Ultrasound is very important in establishing gestational

age and expected date of delivery (EDD). When the

ultrasound technologist is performing a second or third

prenatal exam and the measurements suggest either an

earlier or later EDD, he or she should not change the dates

from the earlier studies. The fetus may be considered

large or small for the date; more important, a small fetus

should raise concern about the possibility of growth

retardation.

Obstetrical Ultrasound

• When evaluating twin pregnancy, chorionicity and

amnionicity should always be determined. The chorion is

the membrane from which the placenta is derived. With

twins there can be one placenta (monochorionic) or two

(dichorionic). Chorionicity therefore defines the number of

placentas in twins. Similarly, amnionicity defines the

number of sacs, i.e., monoamniotic or diamniotic.

Morbidity is much

higher for

monchorionic and

monoamniotic

twins, and there is

a higher rate of

complication, such

as twin-to-twin transfusion syndrome. Chorionicity and

amnionicity should be documented in the radiology report

so that close serial exams can be performed.

• If there is uncertainty about the findings, the patient

should be referred to a radiologist specializing in prenatal

ultrasound, or to a perinatologist.

* * * *

• Radiologists are not required to be present at every

ultrasound exam, but if any question or doubt arises

regarding a scan performed by an ultrasound technologist,

the radiologist should participate in the scanning process.

• Any limitation to the study that compromises the

interpretation, such as bowel gas, patient motion, etc.,

should be reported.

Claims involving obstetrical ultrasound in particular can be

quite costly due to the involvement of infants with potentially

lifelong disabilities or death.

RISK MANAGEMENT RECOMMENDATIONS

• Ultrasound is very important in establishing gestational

age and expected date of delivery (EDD). When the

ultrasound technologist is performing a second or third

prenatal exam and the measurements suggest either an

earlier or later EDD, he or she should not change the dates

from the earlier studies. The fetus may be considered

large or small for the date; more important, a small fetus

should raise concern about the possibility of growth

retardation.

Obstetrical Ultrasound

• When evaluating twin pregnancy, chorionicity and

amnionicity should always be determined. The chorion is

the membrane from which the placenta is derived. With

twins there can be one placenta (monochorionic) or two

(dichorionic). Chorionicity therefore defines the number of

placentas in twins. Similarly, amnionicity defines the

number of sacs, i.e., monoamniotic or diamniotic.

Morbidity is much

higher for

monchorionic and

monoamniotic

twins, and there is

a higher rate of

complication, such

as twin-to-twin transfusion syndrome. Chorionicity and

amnionicity should be documented in the radiology report

so that close serial exams can be performed.

• If there is uncertainty about the findings, the patient

should be referred to a radiologist specializing in prenatal

ultrasound, or to a perinatologist.

* * * *

1. Berlin, L. Accuracy of diagnostic procedures: Has it improved over the past five decades? AJR 2007; 188:1173-78.

2. Borgstede, J.P.; Lewis, R.S.; Bhargavan, M.; et al. RADPEER quality assurance program: A multifacility study of interpretive disagreement rates. JACR 2004; 1:59-65.

3. Brennan, T.A.; Sox, C.M.; Burstin, H.R. Relation between negligent adverse events and the outcomes of medical-malpractice litigation. NEJM 1996; 335:1963-67.

4. Berlin. L.; Berlin, J.W. Malpractice and radiologists in Cook County, IL: Trends in 20 years of litigation. AJR 1995; 165:781-88.

5. Garland, L.H. Studies on the accuracy of diagnostic procedures. AJR 1959; 82:25-38.

6. 32 Ill. Adm. Code 401.

FOOTNOTES