Headache

Variant: 1 Sudden onset severe headache that reaches maximal severity within one hour. Initial imaging.

Procedure	Appropriateness Category	Relative Radiation Level
CT head without IV contrast	Usually Appropriate	☢☢☢
CTA head with IV contrast	May Be Appropriate	☢☢☢
Arteriography cervicocerebral	Usually Not Appropriate	☢☢☢
MRA head with IV contrast	Usually Not Appropriate	O
MRA head without and with IV contrast	Usually Not Appropriate	O
MRA head without IV contrast	Usually Not Appropriate	O
MRI head with IV contrast	Usually Not Appropriate	O
MRI head without and with IV contrast	Usually Not Appropriate	O
MRI head without IV contrast	Usually Not Appropriate	O
MRV head with IV contrast	Usually Not Appropriate	O
MRV head without and with IV contrast	Usually Not Appropriate	O
MRV head without IV contrast	Usually Not Appropriate	O
CT head with IV contrast	Usually Not Appropriate	☢☢☢
CT head without and with IV contrast	Usually Not Appropriate	☢☢☢
CTV head with IV contrast	Usually Not Appropriate	☢☢☢

Variant: 2 Primary migraine or tension-type headache. Normal neurologic examination. Initial imaging.

Procedure	Appropriateness Category	Relative Radiation Level
Arteriography cervicocerebral	Usually Not Appropriate	☢☢☢
MRA head with IV contrast	Usually Not Appropriate	O
MRA head without and with IV contrast	Usually Not Appropriate	O
MRA head without IV contrast	Usually Not Appropriate	O
MRI head with IV contrast	Usually Not Appropriate	O
MRI head without and with IV contrast	Usually Not Appropriate	O
MRI head without IV contrast	Usually Not Appropriate	O
MRV head with IV contrast	Usually Not Appropriate	O
MRV head without and with IV contrast	Usually Not Appropriate	O
MRV head without IV contrast	Usually Not Appropriate	O
CT head with IV contrast	Usually Not Appropriate	☢☢☢
CT head without and with IV contrast	Usually Not Appropriate	☢☢☢
CT head without IV contrast	Usually Not Appropriate	☢☢☢
CTA head with IV contrast	Usually Not Appropriate	☢☢☢
CTV head with IV contrast	Usually Not Appropriate	☢☢☢

Variant: 3 Primary trigeminal autonomic cephalalgias (eg, cluster headache). Initial imaging.

Procedure	Appropriateness Category	Relative Radiation Level
MRI head without and with IV contrast	Usually Appropriate	O
MRI head without IV contrast	May Be Appropriate	O
Arteriography cervicocerebral	Usually Not Appropriate	☢☢☢
MRA head with IV contrast	Usually Not Appropriate	O
MRA head without and with IV contrast	Usually Not Appropriate	O
MRA head without IV contrast	Usually Not Appropriate	O
MRI head with IV contrast	Usually Not Appropriate	O
MRV head with IV contrast	Usually Not Appropriate	O
MRV head without and with IV contrast	Usually Not Appropriate	O
MRV head without IV contrast	Usually Not Appropriate	O
CT head with IV contrast	Usually Not Appropriate	☢☢☢
CT head without and with IV contrast	Usually Not Appropriate	☢☢☢
CT head without IV contrast	Usually Not Appropriate	☢☢☢
CTA head with IV contrast	Usually Not Appropriate	☢☢☢
CTV head with IV contrast	Usually Not Appropriate	☢☢☢

Variant: 4 Headache with features of intracranial hypertension (eg, papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva). Initial imaging.

Procedure	Appropriateness Category	Relative Radiation Level
MRI head without and with IV contrast	Usually Appropriate	O
MRI head without IV contrast	Usually Appropriate	O
CT head without IV contrast	Usually Appropriate	☢☢☢
MRV head with IV contrast	May Be Appropriate	O
MRV head without and with IV contrast	May Be Appropriate	O
MRV head without IV contrast	May Be Appropriate	O
CTV head with IV contrast	May Be Appropriate	☢☢☢
Arteriography cervicocerebral	Usually Not Appropriate	☢☢☢
MRA head with IV contrast	Usually Not Appropriate	O
MRA head without and with IV contrast	Usually Not Appropriate	O
MRA head without IV contrast	Usually Not Appropriate	O
MRI head with IV contrast	Usually Not Appropriate	O
CT head with IV contrast	Usually Not Appropriate	☢☢☢
CT head without and with IV contrast	Usually Not Appropriate	☢☢☢
CTA head with IV contrast	Usually Not Appropriate	☢☢☢

Variant: 5 Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.

Procedure	Appropriateness Category	Relative Radiation Level
MRI head without and with IV contrast	Usually Appropriate	O
MRI thoracic spine with IV contrast	May Be Appropriate (Disagreement)	O
MRI thoracic spine without and with IV contrast	May Be Appropriate	O
MRI thoracic spine without IV contrast	May Be Appropriate	O
Arteriography cervicocerebral	Usually Not Appropriate	☢☢☢
MRA head with IV contrast	Usually Not Appropriate	O
MRA head without and with IV contrast	Usually Not Appropriate	O
MRA head without IV contrast	Usually Not Appropriate	O
MRI head with IV contrast	Usually Not Appropriate	O
MRI head without IV contrast	Usually Not Appropriate	O
MRV head with IV contrast	Usually Not Appropriate	O
MRV head without and with IV contrast	Usually Not Appropriate	O
MRV head without IV contrast	Usually Not Appropriate	O
CT head with IV contrast	Usually Not Appropriate	☢☢☢
CT head without and with IV contrast	Usually Not Appropriate	☢☢☢
CT head without IV contrast	Usually Not Appropriate	☢☢☢
CTA head with IV contrast	Usually Not Appropriate	☢☢☢
CTV head with IV contrast	Usually Not Appropriate	☢☢☢

Variant: 6 Headache with new onset or pattern during pregnancy or peripartum period. Initial imaging.

Procedure	Appropriateness Category	Relative Radiation Level
MRI head without IV contrast	Usually Appropriate	O
CT head without IV contrast	Usually Appropriate	☢☢☢
MRV head without IV contrast	May Be Appropriate	O
CTV head with IV contrast	May Be Appropriate	☢☢☢
Arteriography cervicocerebral	Usually Not Appropriate	☢☢☢
MRA head with IV contrast	Usually Not Appropriate	O
MRA head without and with IV contrast	Usually Not Appropriate	O
MRA head without IV contrast	Usually Not Appropriate	O
MRI head with IV contrast	Usually Not Appropriate	O
MRI head without and with IV contrast	Usually Not Appropriate	O
MRV head with IV contrast	Usually Not Appropriate	O
MRV head without and with IV contrast	Usually Not Appropriate	O
CT head with IV contrast	Usually Not Appropriate	☢☢☢
CT head without and with IV contrast	Usually Not Appropriate	☢☢☢
CTA head with IV contrast	Usually Not Appropriate	☢☢☢

Variant: 7 Headache with one or more of the following “red flags”: increasing frequency or severity, fever or neurologic deficit, history of cancer or immunocompromise, older age (>50 years) of onset, or posttraumatic onset. Initial imaging.

Procedure	Appropriateness Category	Relative Radiation Level
MRI head without and with IV contrast	Usually Appropriate	O
MRI head without IV contrast	Usually Appropriate	O
CT head without IV contrast	Usually Appropriate	☢☢☢
Arteriography cervicocerebral	Usually Not Appropriate	☢☢☢
MRA head with IV contrast	Usually Not Appropriate	O
MRA head without and with IV contrast	Usually Not Appropriate	O
MRA head without IV contrast	Usually Not Appropriate	O
MRI head with IV contrast	Usually Not Appropriate	O
MRV head with IV contrast	Usually Not Appropriate	O
MRV head without and with IV contrast	Usually Not Appropriate	O
MRV head without IV contrast	Usually Not Appropriate	O
CT head with IV contrast	Usually Not Appropriate	☢☢☢
CT head without and with IV contrast	Usually Not Appropriate	☢☢☢
CTA head with IV contrast	Usually Not Appropriate	☢☢☢
CTV head with IV contrast	Usually Not Appropriate	☢☢☢

Variant: 8 Headache without any of the following “red flags”: sudden onset ("thunderclap"), features of intracranial hypertension or hypotension, new onset or pattern during pregnancy or peripartum period, increasing frequency or severity, fever or neurologic deficit, history of cancer or immunocompromise, older age (greater than 50 years of age) of onset, or post-traumatic onset. Initial imaging.

Procedure	Appropriateness Category	Relative Radiation Level
Arteriography cervicocerebral	Usually Not Appropriate	☢☢☢
MRA head with IV contrast	Usually Not Appropriate	O
MRA head without and with IV contrast	Usually Not Appropriate	O
MRA head without IV contrast	Usually Not Appropriate	O
MRI head with IV contrast	Usually Not Appropriate	O
MRI head without and with IV contrast	Usually Not Appropriate	O
MRI head without IV contrast	Usually Not Appropriate	O
MRV head with IV contrast	Usually Not Appropriate	O
MRV head without and with IV contrast	Usually Not Appropriate	O
MRV head without IV contrast	Usually Not Appropriate	O
CT head with IV contrast	Usually Not Appropriate	☢☢☢
CT head without and with IV contrast	Usually Not Appropriate	☢☢☢
CT head without IV contrast	Usually Not Appropriate	☢☢☢
CTA head with IV contrast	Usually Not Appropriate	☢☢☢
CTV head with IV contrast	Usually Not Appropriate	☢☢☢

Panel Members

Pallavi S. Utukuri, MD^a; Robert Y. Shih, MD^b; Amna A. Ajam, MD, MBBS^c; Kathryn E. Callahan, MD, MS^d; Doris Chen, MD^e; Jeffrey W. Dunkle, MD^f; Christopher H. Hunt, MD^g; Jana Ivanidze, MD^h; Luke N. Ledbetter, MDⁱ; Ryan K. Lee, ^j; Omojo Malu, MD^k; Jeffrey S. Pannell, MD^l; Jeffrey M. Pollock, MD^m; Sonja X. Potrebic, MDⁿ; Michael Setzen, MD^o; Richard D. Shih, MD^p; Bruno P. Soares, MD^q; Michael D. Staudt, MD, MSc^r; Lily L. Wang, MBBS, MPH^s; Judah Burns, MD^t.

Summary of Literature Review

Introduction/Background

Initial Imaging Definition

Initial imaging is defined as imaging at the beginning of the care episode for the medical condition defined by the variant. More than one procedure can be considered usually appropriate in the initial imaging evaluation when:

There are procedures that are equivalent alternatives (i.e., only one procedure will be ordered to provide the clinical information to effectively manage the patient’s care)

There are complementary procedures (i.e., more than one procedure is ordered as a set or simultaneously wherein each procedure provides unique clinical information to effectively manage the patient’s care).

Discussion of Procedures by Variant

Variant 1: Sudden onset severe headache that reaches maximal severity within one hour. Initial imaging.

Variant 1: Sudden onset severe headache that reaches maximal severity within one hour. Initial imaging.
A. Arteriography cervicocerebral

Variant 1: Sudden onset severe headache that reaches maximal severity within one hour. Initial imaging.
B. CT head with IV contrast

Variant 1: Sudden onset severe headache that reaches maximal severity within one hour. Initial imaging.
C. CT head without and with IV contrast

Variant 1: Sudden onset severe headache that reaches maximal severity within one hour. Initial imaging.
D. CT head without IV contrast

Variant 1: Sudden onset severe headache that reaches maximal severity within one hour. Initial imaging.
E. CTA head with IV contrast

Variant 1: Sudden onset severe headache that reaches maximal severity within one hour. Initial imaging.
F. CTV head with IV contrast

Variant 1: Sudden onset severe headache that reaches maximal severity within one hour. Initial imaging.
G. MRA head with IV contrast

Variant 1: Sudden onset severe headache that reaches maximal severity within one hour. Initial imaging.
H. MRA head without and with IV contrast

Variant 1: Sudden onset severe headache that reaches maximal severity within one hour. Initial imaging.
I. MRA head without IV contrast

Variant 1: Sudden onset severe headache that reaches maximal severity within one hour. Initial imaging.
J. MRI head with IV contrast

Variant 1: Sudden onset severe headache that reaches maximal severity within one hour. Initial imaging.
K. MRI head without and with IV contrast

Variant 1: Sudden onset severe headache that reaches maximal severity within one hour. Initial imaging.
L. MRI head without IV contrast

Variant 1: Sudden onset severe headache that reaches maximal severity within one hour. Initial imaging.
M. MRV head with IV contrast

Variant 1: Sudden onset severe headache that reaches maximal severity within one hour. Initial imaging.
N. MRV head without and with IV contrast

Variant 1: Sudden onset severe headache that reaches maximal severity within one hour. Initial imaging.
O. MRV head without IV contrast

Variant 2: Primary migraine or tension-type headache. Normal neurologic examination. Initial imaging.

Variant 2: Primary migraine or tension-type headache. Normal neurologic examination. Initial imaging.
A. Arteriography cervicocerebral

Variant 2: Primary migraine or tension-type headache. Normal neurologic examination. Initial imaging.
B. CT head with IV contrast

Variant 2: Primary migraine or tension-type headache. Normal neurologic examination. Initial imaging.
C. CT head without and with IV contrast

Variant 2: Primary migraine or tension-type headache. Normal neurologic examination. Initial imaging.
D. CT head without IV contrast

Variant 2: Primary migraine or tension-type headache. Normal neurologic examination. Initial imaging.
E. CTA head with IV contrast

Variant 2: Primary migraine or tension-type headache. Normal neurologic examination. Initial imaging.
F. CTV head with IV contrast

Variant 2: Primary migraine or tension-type headache. Normal neurologic examination. Initial imaging.
G. MRA head with IV contrast

Variant 2: Primary migraine or tension-type headache. Normal neurologic examination. Initial imaging.
H. MRA head without and with IV contrast

Variant 2: Primary migraine or tension-type headache. Normal neurologic examination. Initial imaging.
I. MRA head without IV contrast

Variant 2: Primary migraine or tension-type headache. Normal neurologic examination. Initial imaging.
J. MRI head with IV contrast

Variant 2: Primary migraine or tension-type headache. Normal neurologic examination. Initial imaging.
K. MRI head without and with IV contrast

Variant 2: Primary migraine or tension-type headache. Normal neurologic examination. Initial imaging.
L. MRI head without IV contrast

Variant 2: Primary migraine or tension-type headache. Normal neurologic examination. Initial imaging.
M. MRV head with IV contrast

Variant 2: Primary migraine or tension-type headache. Normal neurologic examination. Initial imaging.
N. MRV head without and with IV contrast

Variant 2: Primary migraine or tension-type headache. Normal neurologic examination. Initial imaging.
O. MRV head without IV contrast

Variant 3: Primary trigeminal autonomic cephalalgias (eg, cluster headache). Initial imaging.

Variant 3: Primary trigeminal autonomic cephalalgias (eg, cluster headache). Initial imaging.
A. Arteriography cervicocerebral

Variant 3: Primary trigeminal autonomic cephalalgias (eg, cluster headache). Initial imaging.
B. CT head with IV contrast

Variant 3: Primary trigeminal autonomic cephalalgias (eg, cluster headache). Initial imaging.
C. CT head without and with IV contrast

Variant 3: Primary trigeminal autonomic cephalalgias (eg, cluster headache). Initial imaging.
D. CT head without IV contrast

Variant 3: Primary trigeminal autonomic cephalalgias (eg, cluster headache). Initial imaging.
E. CTA head with IV contrast

Variant 3: Primary trigeminal autonomic cephalalgias (eg, cluster headache). Initial imaging.
F. CTV head with IV contrast

Variant 3: Primary trigeminal autonomic cephalalgias (eg, cluster headache). Initial imaging.
G. MRA head with IV contrast

Variant 3: Primary trigeminal autonomic cephalalgias (eg, cluster headache). Initial imaging.
H. MRA head without and with IV contrast

Variant 3: Primary trigeminal autonomic cephalalgias (eg, cluster headache). Initial imaging.
I. MRA head without IV contrast

Variant 3: Primary trigeminal autonomic cephalalgias (eg, cluster headache). Initial imaging.
J. MRI head with IV contrast

Variant 3: Primary trigeminal autonomic cephalalgias (eg, cluster headache). Initial imaging.
K. MRI head without and with IV contrast

Variant 3: Primary trigeminal autonomic cephalalgias (eg, cluster headache). Initial imaging.
L. MRI head without IV contrast

Variant 3: Primary trigeminal autonomic cephalalgias (eg, cluster headache). Initial imaging.
M. MRV head with IV contrast

Variant 3: Primary trigeminal autonomic cephalalgias (eg, cluster headache). Initial imaging.
N. MRV head without and with IV contrast

Variant 3: Primary trigeminal autonomic cephalalgias (eg, cluster headache). Initial imaging.
O. MRV head without IV contrast

Variant 4: Headache with features of intracranial hypertension (eg, papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva). Initial imaging.

Variant 4: Headache with features of intracranial hypertension (eg, papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva). Initial imaging.
A. Arteriography cervicocerebral

Variant 4: Headache with features of intracranial hypertension (eg, papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva). Initial imaging.
B. CT head with IV contrast

Variant 4: Headache with features of intracranial hypertension (eg, papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva). Initial imaging.
C. CT head without and with IV contrast

Variant 4: Headache with features of intracranial hypertension (eg, papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva). Initial imaging.
D. CT head without IV contrast

Variant 4: Headache with features of intracranial hypertension (eg, papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva). Initial imaging.
E. CTA head with IV contrast

Variant 4: Headache with features of intracranial hypertension (eg, papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva). Initial imaging.
F. CTV head with IV contrast

Variant 4: Headache with features of intracranial hypertension (eg, papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva). Initial imaging.
G. MRA head with IV contrast

Variant 4: Headache with features of intracranial hypertension (eg, papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva). Initial imaging.
H. MRA head without and with IV contrast

Variant 4: Headache with features of intracranial hypertension (eg, papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva). Initial imaging.
I. MRA head without IV contrast

Variant 4: Headache with features of intracranial hypertension (eg, papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva). Initial imaging.
J. MRI head with IV contrast

Variant 4: Headache with features of intracranial hypertension (eg, papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva). Initial imaging.
K. MRI head without and with IV contrast

Variant 4: Headache with features of intracranial hypertension (eg, papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva). Initial imaging.
L. MRI head without IV contrast

Variant 4: Headache with features of intracranial hypertension (eg, papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva). Initial imaging.
M. MRV head with IV contrast

Variant 4: Headache with features of intracranial hypertension (eg, papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva). Initial imaging.
N. MRV head without and with IV contrast

Variant 4: Headache with features of intracranial hypertension (eg, papilledema, pulsatile tinnitus, visual symptoms worse on Valsalva). Initial imaging.
O. MRV head without IV contrast

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
A. Arteriography cervicocerebral

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
B. CT head with IV contrast

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
C. CT head without and with IV contrast

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
D. CT head without IV contrast

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
E. CTA head with IV contrast

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
F. CTV head with IV contrast

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
G. MRA head with IV contrast

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
H. MRA head without and with IV contrast

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
I. MRA head without IV contrast

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
J. MRI head with IV contrast

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
K. MRI head without and with IV contrast

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
L. MRI head without IV contrast

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
M. MRI thoracic spine with IV contrast

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
N. MRI thoracic spine without and with IV contrast

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
O. MRI thoracic spine without IV contrast

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
P. MRV head with IV contrast

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
Q. MRV head without and with IV contrast

Variant 5: Headache with features of intracranial hypotension (eg, positional, worse when upright, better when lying down). Initial imaging.
R. MRV head without IV contrast

Variant 6: Headache with new onset or pattern during pregnancy or peripartum period. Initial imaging.

Variant 6: Headache with new onset or pattern during pregnancy or peripartum period. Initial imaging.
A. Arteriography cervicocerebral

Variant 6: Headache with new onset or pattern during pregnancy or peripartum period. Initial imaging.
B. CT head with IV contrast

Variant 6: Headache with new onset or pattern during pregnancy or peripartum period. Initial imaging.
C. CT head without and with IV contrast

Variant 6: Headache with new onset or pattern during pregnancy or peripartum period. Initial imaging.
D. CT head without IV contrast

Variant 6: Headache with new onset or pattern during pregnancy or peripartum period. Initial imaging.
E. CTA head with IV contrast

Variant 6: Headache with new onset or pattern during pregnancy or peripartum period. Initial imaging.
F. CTV head with IV contrast

Variant 6: Headache with new onset or pattern during pregnancy or peripartum period. Initial imaging.
G. MRA head with IV contrast

Variant 6: Headache with new onset or pattern during pregnancy or peripartum period. Initial imaging.
H. MRA head without and with IV contrast

Variant 6: Headache with new onset or pattern during pregnancy or peripartum period. Initial imaging.
I. MRA head without IV contrast

Variant 6: Headache with new onset or pattern during pregnancy or peripartum period. Initial imaging.
J. MRI head with IV contrast

Variant 6: Headache with new onset or pattern during pregnancy or peripartum period. Initial imaging.
K. MRI head without and with IV contrast

Variant 6: Headache with new onset or pattern during pregnancy or peripartum period. Initial imaging.
L. MRI head without IV contrast

Variant 6: Headache with new onset or pattern during pregnancy or peripartum period. Initial imaging.
M. MRV head with IV contrast

Variant 6: Headache with new onset or pattern during pregnancy or peripartum period. Initial imaging.
N. MRV head without and with IV contrast

Variant 6: Headache with new onset or pattern during pregnancy or peripartum period. Initial imaging.
O. MRV head without IV contrast

Variant 7: Headache with one or more of the following "red flags”: increasing frequency or severity, fever or neurologic deficit, history of cancer or immunocompromise, older age (>50 years) of onset, or posttraumatic onset. Initial imaging.

Variant 8: Headache without any of the following "red flags”: sudden onset ("thunderclap"), features of intracranial hypertension or hypotension, new onset or pattern during pregnancy or peripartum period, increasing frequency or severity, fever or neurologic deficit, history of cancer or immunocompromise, older age (greater than 50 years of age) of onset, or post-traumatic onset. Initial imaging.

Summary of Highlights

Supporting Documents

The evidence table, literature search, and appendix for this topic are available at https://acsearch.acr.org/list. The appendix includes the strength of evidence assessment and the final rating round tabulations for each recommendation.

For additional information on the Appropriateness Criteria methodology and other supporting documents, please go to the ACR website at https://www.acr.org/Clinical-Resources/Clinical-Tools-and-Reference/Appropriateness-Criteria.

Safety Considerations in Pregnant Patients

Imaging of the pregnant patient can be challenging, particularly with respect to minimizing radiation exposure and risk. For further information and guidance, see the following ACR documents:

· ACR–SPR Practice Parameter for the Safe and Optimal Performance of Fetal Magnetic Resonance Imaging (MRI)

· ACR-SPR Practice Parameter for Imaging Pregnant or Potentially Pregnant Patients with Ionizing Radiation

· ACR-ACOG-AIUM-SMFM-SRU Practice Parameter for the Performance of Standard Diagnostic Obstetrical Ultrasound

· ACR Manual on Contrast Media

· ACR Manual on MR Safety

Appropriateness Category Names and Definitions

Appropriateness Category Name	Appropriateness Rating	Appropriateness Category Definition
Usually Appropriate	7, 8, or 9	The imaging procedure or treatment is indicated in the specified clinical scenarios at a favorable risk-benefit ratio for patients.
May Be Appropriate	4, 5, or 6	The imaging procedure or treatment may be indicated in the specified clinical scenarios as an alternative to imaging procedures or treatments with a more favorable risk-benefit ratio, or the risk-benefit ratio for patients is equivocal.
May Be Appropriate (Disagreement)	5	The individual ratings are too dispersed from the panel median. The different label provides transparency regarding the panel’s recommendation. “May be appropriate” is the rating category and a rating of 5 is assigned.
Usually Not Appropriate	1, 2, or 3	The imaging procedure or treatment is unlikely to be indicated in the specified clinical scenarios, or the risk-benefit ratio for patients is likely to be unfavorable.

Relative Radiation Level Information

Potential adverse health effects associated with radiation exposure are an important factor to consider when selecting the appropriate imaging procedure. Because there is a wide range of radiation exposures associated with different diagnostic procedures, a relative radiation level (RRL) indication has been included for each imaging examination. The RRLs are based on effective dose, which is a radiation dose quantity that is used to estimate population total radiation risk associated with an imaging procedure. Patients in the pediatric age group are at inherently higher risk from exposure, because of both organ sensitivity and longer life expectancy (relevant to the long latency that appears to accompany radiation exposure). For these reasons, the RRL dose estimate ranges for pediatric examinations are lower as compared with those specified for adults (see Table below). Additional information regarding radiation dose assessment for imaging examinations can be found in the ACR Appropriateness Criteria^® Radiation Dose Assessment Introduction document.

Relative Radiation Level Designations
Relative Radiation Level*	Adult Effective Dose Estimate Range	Pediatric Effective Dose Estimate Range
O	0 mSv	0 mSv
☢	<0.1 mSv	<0.03 mSv
☢☢	0.1-1 mSv	0.03-0.3 mSv
☢☢☢	1-10 mSv	0.3-3 mSv
☢☢☢☢	10-30 mSv	3-10 mSv
☢☢☢☢☢	30-100 mSv	10-30 mSv
*RRL assignments for some of the examinations cannot be made, because the actual patient doses in these procedures vary as a function of a number of factors (e.g., region of the body exposed to ionizing radiation, the imaging guidance that is used). The RRLs for these examinations are designated as “Varies.”

References

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Disclaimer

The ACR Committee on Appropriateness Criteria and its expert panels have developed criteria for determining appropriate imaging examinations for diagnosis and treatment of specified medical condition(s). These criteria are intended to guide radiologists, radiation oncologists and referring physicians in making decisions regarding radiologic imaging and treatment. Generally, the complexity and severity of a patient’s clinical condition should dictate the selection of appropriate imaging procedures or treatments. Only those examinations generally used for evaluation of the patient’s condition are ranked. Other imaging studies necessary to evaluate other co-existent diseases or other medical consequences of this condition are not considered in this document. The availability of equipment or personnel may influence the selection of appropriate imaging procedures or treatments. Imaging techniques classified as investigational by the FDA have not been considered in developing these criteria; however, study of new equipment and applications should be encouraged. The ultimate decision regarding the appropriateness of any specific radiologic examination or treatment must be made by the referring physician and radiologist in light of all the circumstances presented in an individual examination.