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The Hounsfield scale /ˈhaʊnzˌfiːld/, named after Sir Godfrey Hounsfield, is a quantitative scale for describing radiodensity. It is frequently used in CT scans, where its value is also termed CT number.

Definition

The Hounsfield unit (HU) scale is a linear transformation of the original linear attenuation coefficient measurement into one in which the radiodensity of distilled water at standard pressure and temperature (STP) is defined as zero Hounsfield units (HU), while the radiodensity of air at STP is defined as −1000 HU. In a voxel with average linear attenuation coefficient $\mu$ , the corresponding HU value is therefore given by:

$HU=1000\times {\frac {\mu -\mu _{\textrm {water}}}{\mu _{\textrm {water}}-\mu _{\textrm {air}}}}$

where $\mu _{\textrm {water}}$ and $\mu _{\textrm {air}}$ are respectively the linear attenuation coefficients of water and air.

Thus, a change of one Hounsfield unit (HU) represents a change of 0.1% of the attenuation coefficient of water since the attenuation coefficient of air is nearly zero.

It is the definition for CT scanners that are calibrated with reference to water.

Rationale

The above standards were chosen as they are universally available references and suited to the key application for which computed axial tomography was developed: imaging the internal anatomy of living creatures based on organized water structures and mostly living in air, e.g. humans.

Value in parts of the body

The Hounsfield scale applies to medical-grade CT scans but not to cone beam computed tomography (CBCT) scans.^[1]

Substance		HU
Air		−1000
Fat		−120 to −90^[2]
Soft tissue on contrast CT		+100 to +300
Bone	Cancellous	+300 to +400^[3]
Bone	Cortical	+1800 to +1900^[3]
Subdural hematoma	First hours	+75 to +100^[4]
	After 3 days	+65 to +85^[4]
	After 10–14 days	+35 to +40^[5]
Other blood	Unclotted	+13^[6] to +50^[7]
Other blood	Clotted	+50^[8] to +75^[6]^[8]
Pleural effusion	Transudate	+2 to +15 ^[9]
Pleural effusion	Exudate	+4 to +33^[9]
Other fluids	Chyle	−30^[10]
	Water	0
	Urine	−5 to +15^[2]
	Bile	−5 to +15^[2]
	CSF	+15
	Abscess / Pus	0^[11] or +20,^[12] to +40^[12] or +45^[11]
	Mucus	0^[13] - 130^[14] ("high attenuating" at over 70 HU)^[15]^[16]
Parenchyma	Lung	−700 to −600^[17]
	Kidney	+20 to +45^[2]
	Liver	60 ± 6^[18]
	Lymph nodes	+10 to +20^[19]
	Muscle	+35 to +55^[2]
	Thymus	+20 to +40 in children^[20] +20 to +120 in adolescents^[20]
	White matter	+20 to +30
	Grey matter	+37 to +45
Gallstone	Cholesterol stone	+30 to +100^[21]
Gallstone	Bilirubin stone	+90 to +120^[21]
Foreign body^[22]	Windowpane glass	+500
	Aluminum, tarmac, car window glass, bottle glass, and other rocks	+2,100 to +2,300
	Limestone	+2,800
	Copper	+14,000
	Silver	+17,000
	Steel	+20,000
	Gold, steel, and brass	+30,000 (upper measurable limit)
Earwax		<0

A practical application of this is in evaluation of tumors, where, for example, an adrenal tumor with a radiodensity of less than 10 HU is rather fatty in composition and almost certainly a benign adrenal adenoma.^[23]

References

Feeman, Timothy G. (2010). The Mathematics of Medical Imaging: A Beginner's Guide. Springer Undergraduate Texts in Mathematics and Technology. Springer. ISBN 978-0387927114.

Notes

^ De Vos, W.; Casselman, J.; Swennen, G.R.J. (June 2009). "Cone-beam computerized tomography (CBCT) imaging of the oral and maxillofacial region: A systematic review of the literature". International Journal of Oral and Maxillofacial Surgery. 38 (6): 609–625. doi:10.1016/j.ijom.2009.02.028. PMID 19464146.
^ ^a ^b ^c ^d ^e Page 83 in: Herbert Lepor (2000). Prostatic Diseases. W.B. Saunders Company. ISBN 9780721674162.
^ ^a ^b Birur, NPraveen; Patrick, Sanjana; Gurushanth, Keerthi; Raghavan, AShubhasini; Gurudath, Shubha (2017). "Comparison of gray values of cone-beam computed tomography with hounsfield units of multislice computed tomography: An in vitro study". Indian Journal of Dental Research. 28 (1): 66–70. doi:10.4103/ijdr.IJDR_415_16. ISSN 0970-9290. PMID 28393820.{{cite journal}}: CS1 maint: unflagged free DOI (link)
^ ^a ^b Fig 3 in: Rao, Murali Gundu (2016). "Dating of Early Subdural Haematoma: A Correlative Clinico-Radiological Study". Journal of Clinical and Diagnostic Research. 10 (4): HC01–5. doi:10.7860/JCDR/2016/17207.7644. ISSN 2249-782X. PMC 4866129. PMID 27190831.
^ Dr Rohit Sharma & A.Prof Frank Gaillard. "Subdural haemorrhage". Radiopaedia. Retrieved 2018-08-14.
^ ^a ^b Page 263 in: Robert Fosbinder; Denise Orth (2011). Essentials of Radiologic Science. Lippincott Williams & Wilkins. ISBN 9780781775540.
^ page 20.17 in: F W Wright (2001). Radiology of the Chest and Related Conditions. CRC Press. ISBN 9780415281416.
^ ^a ^b page 17 in: Dr. Avital Fast; Dorith Goldsher (2006). Navigating the Adult Spine: Bridging Clinical Practice and Neuroradiology. Demos Medical Publishing. ISBN 9781934559741.
^ ^a ^b Cullu, Nesat; Kalemci, Serdar; Karakas, Omer; Eser, Irfan; Yalcin, Funda; Boyaci, Fatma Nurefsan; Karakas, Ekrem (2013). "Efficacy of CT in diagnosis of transudates and exudates in patients with pleural effusion". Diagnostic and Interventional Radiology. 20 (2): 116–20. doi:10.5152/dir.2013.13066. ISSN 1305-3825. PMC 4463296. PMID 24100060.
^ Page 342 in: Luca Saba; Jasjit S. Suri (2013). Multi-Detector CT Imaging: Principles, Head, Neck, and Vascular Systems, Volume 1. CRC Press. ISBN 9781439893845.
^ ^a ^b P. Sanchez de Medina Alba; C. Santos Montón; N. Calvo; K. El Karzazi; T. González de la Huebra Labrador; R. Corrales; N. Alegre Borge; Salamanca/ES. (2014). "Liver abscesses: where do they come from?A review of the main types of liver abscesses and the correlation between their causes and the radiologic findings". ECR 2014. doi:10.1594/ecr2014/C-1927.
^ ^a ^b Sasaki, Toru; Miyata, Rie; Hatai, Yoshiho; Makita, Kohzoh; Tsunoda, Koichi (2014). "Hounsfield unit values of retropharyngeal abscess-like lesions seen in Kawasaki disease". Acta Oto-Laryngologica. 134 (4): 437–440. doi:10.3109/00016489.2013.878475. ISSN 0001-6489. PMID 24512428.
^ K SAGGAR, A AHLUWALIA; P SANDHU, V KALIA (2006). "Mucocoele Of The Appendix" (PDF). Ind J Radiol Imag. 16 (2).
^ Gaeta, Michele; Vinci, Sergio; Minutoli, Fabio; Mazziotti, Silvio; Ascenti, Giorgio; Salamone, Ignazio; Lamberto, Salvatore; Blandino, Alfredo (2001). "CT and MRI findings of mucin-containing tumors and pseudotumors of the thorax: pictorial review". European Radiology. 12 (1): 181–189. doi:10.1007/s003300100934. ISSN 0938-7994. PMID 11868096.
^ Subash S Phuyal; Mandeep Kumar MK Garg; Ritesh R Agarwal; Pankaj P Gupta; Arunaloke A Chakrabarti; Manavjit Singh MS Sandhu; Niranjan N Khandelwal (2015-09-02). "High-Attenuation Mucus Impaction in Patients With Allergic Bronchopulmonary Aspergillosis: Objective Criteria on High-Resolution Computed Tomography and Correlation With Serologic Parameters". Current Problems in Diagnostic Radiology.
^ Agarwal, Ritesh; Sehgal, Inderpaul Singh; Dhooria, Sahajal; Aggarwal, Ashutosh (2016). "Radiologic Criteria for the Diagnosis of High-Attenuation Mucus in Allergic Bronchopulmonary Aspergillosis". Chest. 149 (4): 1109–1110. doi:10.1016/j.chest.2015.12.043. ISSN 0012-3692. PMID 27055707.
^ Page 379 in: Ella A. Kazerooni; Barry H. Gross (2004). Cardiopulmonary Imaging. Vol. 4. Lippincott Williams & Wilkins. ISBN 9780781736558.
^ page 210 in: Erwin Kuntz; Hans-Dieter Kuntz (2006). Hepatology, Principles and Practice: History, Morphology, Biochemistry, Diagnostics, Clinic, Therapy. Springer Science & Business Media. ISBN 9783540289777.
^ Page 58 in: G. Maatman (2012). High-Resolution Computed Tomography of the Paranasal Sinuses and Pharynx and Related Regions: Impact of CT identification on diagnosis and patient management. Volume 12 of Series in Radiology. Springer Science & Business Media. ISBN 9789400942776.
^ ^a ^b Page 488 in: Jean-Claude Givel; Marco Merlini; David B. Clarke; Michael Dusmet (2012). Surgery of the Thymus: Pathology, Associated Disorders and Surgical Technique. Springer Science & Business Media. ISBN 9783642710766.
^ ^a ^b Rambow A, Staritz M, Wosiewitz U, Mildenburger P, Thelen M, Meyer zum Büschenfelde KH (1990). "Analysis of radiolucent gallstones by computed tomography for in vivo estimation of stone components". Eur J Clin Invest. 20 (4): 475–8. doi:10.1111/j.1365-2362.1990.tb01887.x. PMID 2121509.
^ Bolliger, Stephan A.; Oesterhelweg, Lars; Spendlove, Danny; Ross, Steffen; Thali, Michael J. (2009). "Is Differentiation of Frequently Encountered Foreign Bodies in Corpses Possible by Hounsfield Density Measurement?". Journal of Forensic Sciences. 54 (5): 1119–1122. doi:10.1111/j.1556-4029.2009.01100.x. ISSN 0022-1198. PMID 19627414.
^ medscape >Adrenal Adenoma Imaging. Author: Perry J Horwich. Chief Editor: Eugene C Lin. Updated: Apr 21, 2011

External links

"Hounsfield unit". Medcyclopaedia. GE. Archived from the original on 2012-04-04.
Hounsfield Unit - fpnotebook.com
"Introduction to CT physics" (PDF). elsevierhealth.com. Archived from the original (PDF) on 2007-09-26.
Imaging of deep brain stimulation leads using extended Hounsfield unit CT. Stereotact Funct Neurosurg. 2009;87(3):155-60. doi: 10.1159/000209296

[DEVOS-1] De Vos, W.; Casselman, J.; Swennen, G.R.J. (June 2009). "Cone-beam computerized tomography (CBCT) imaging of the oral and maxillofacial region: A systematic review of the literature". International Journal of Oral and Maxillofacial Surgery. 38 (6): 609–625. doi:10.1016/j.ijom.2009.02.028. PMID 19464146.

[Lepor2000-2] Page 83 in: Herbert Lepor (2000). Prostatic Diseases. W.B. Saunders Company. ISBN 9780721674162.

[BirurPatrick2017-3] Birur, NPraveen; Patrick, Sanjana; Gurushanth, Keerthi; Raghavan, AShubhasini; Gurudath, Shubha (2017). "Comparison of gray values of cone-beam computed tomography with hounsfield units of multislice computed tomography: An in vitro study". Indian Journal of Dental Research. 28 (1): 66–70. doi:10.4103/ijdr.IJDR_415_16. ISSN 0970-9290. PMID 28393820.{{cite journal}}: CS1 maint: unflagged free DOI (link)

[Rao2016-4] Fig 3 in: Rao, Murali Gundu (2016). "Dating of Early Subdural Haematoma: A Correlative Clinico-Radiological Study". Journal of Clinical and Diagnostic Research. 10 (4): HC01–5. doi:10.7860/JCDR/2016/17207.7644. ISSN 2249-782X. PMC 4866129. PMID 27190831.

[5] Dr Rohit Sharma & A.Prof Frank Gaillard. "Subdural haemorrhage". Radiopaedia. Retrieved 2018-08-14.

[fosbinder2011-6] Page 263 in: Robert Fosbinder; Denise Orth (2011). Essentials of Radiologic Science. Lippincott Williams & Wilkins. ISBN 9780781775540.

[7] 20.17 in: F W Wright (2001). Radiology of the Chest and Related Conditions. CRC Press. ISBN 9780415281416.

[fast2006-8] 17 in: Dr. Avital Fast; Dorith Goldsher (2006). Navigating the Adult Spine: Bridging Clinical Practice and Neuroradiology. Demos Medical Publishing. ISBN 9781934559741.

[CulluKalemci2013-9] Cullu, Nesat; Kalemci, Serdar; Karakas, Omer; Eser, Irfan; Yalcin, Funda; Boyaci, Fatma Nurefsan; Karakas, Ekrem (2013). "Efficacy of CT in diagnosis of transudates and exudates in patients with pleural effusion". Diagnostic and Interventional Radiology. 20 (2): 116–20. doi:10.5152/dir.2013.13066. ISSN 1305-3825. PMC 4463296. PMID 24100060.

[10] Page 342 in: Luca Saba; Jasjit S. Suri (2013). Multi-Detector CT Imaging: Principles, Head, Neck, and Vascular Systems, Volume 1. CRC Press. ISBN 9781439893845.

[ecr-11] P. Sanchez de Medina Alba; C. Santos Montón; N. Calvo; K. El Karzazi; T. González de la Huebra Labrador; R. Corrales; N. Alegre Borge; Salamanca/ES. (2014). "Liver abscesses: where do they come from?A review of the main types of liver abscesses and the correlation between their causes and the radiologic findings". ECR 2014. doi:10.1594/ecr2014/C-1927.

[SasakiMiyata2014-12] Sasaki, Toru; Miyata, Rie; Hatai, Yoshiho; Makita, Kohzoh; Tsunoda, Koichi (2014). "Hounsfield unit values of retropharyngeal abscess-like lesions seen in Kawasaki disease". Acta Oto-Laryngologica. 134 (4): 437–440. doi:10.3109/00016489.2013.878475. ISSN 0001-6489. PMID 24512428.

[13] K SAGGAR, A AHLUWALIA; P SANDHU, V KALIA (2006). "Mucocoele Of The Appendix" (PDF). Ind J Radiol Imag. 16 (2).

[GaetaVinci2001-14] Gaeta, Michele; Vinci, Sergio; Minutoli, Fabio; Mazziotti, Silvio; Ascenti, Giorgio; Salamone, Ignazio; Lamberto, Salvatore; Blandino, Alfredo (2001). "CT and MRI findings of mucin-containing tumors and pseudotumors of the thorax: pictorial review". European Radiology. 12 (1): 181–189. doi:10.1007/s003300100934. ISSN 0938-7994. PMID 11868096.

[15] Subash S Phuyal; Mandeep Kumar MK Garg; Ritesh R Agarwal; Pankaj P Gupta; Arunaloke A Chakrabarti; Manavjit Singh MS Sandhu; Niranjan N Khandelwal (2015-09-02). "High-Attenuation Mucus Impaction in Patients With Allergic Bronchopulmonary Aspergillosis: Objective Criteria on High-Resolution Computed Tomography and Correlation With Serologic Parameters". Current Problems in Diagnostic Radiology.

[AgarwalSehgal2016-16] Agarwal, Ritesh; Sehgal, Inderpaul Singh; Dhooria, Sahajal; Aggarwal, Ashutosh (2016). "Radiologic Criteria for the Diagnosis of High-Attenuation Mucus in Allergic Bronchopulmonary Aspergillosis". Chest. 149 (4): 1109–1110. doi:10.1016/j.chest.2015.12.043. ISSN 0012-3692. PMID 27055707.

[17] Page 379 in: Ella A. Kazerooni; Barry H. Gross (2004). Cardiopulmonary Imaging. Vol. 4. Lippincott Williams & Wilkins. ISBN 9780781736558.

[18] 210 in: Erwin Kuntz; Hans-Dieter Kuntz (2006). Hepatology, Principles and Practice: History, Morphology, Biochemistry, Diagnostics, Clinic, Therapy. Springer Science & Business Media. ISBN 9783540289777.

[19] Page 58 in: G. Maatman (2012). High-Resolution Computed Tomography of the Paranasal Sinuses and Pharynx and Related Regions: Impact of CT identification on diagnosis and patient management. Volume 12 of Series in Radiology. Springer Science & Business Media. ISBN 9789400942776.

[givel2012-20] Page 488 in: Jean-Claude Givel; Marco Merlini; David B. Clarke; Michael Dusmet (2012). Surgery of the Thymus: Pathology, Associated Disorders and Surgical Technique. Springer Science & Business Media. ISBN 9783642710766.

[pmid2121509-21] Rambow A, Staritz M, Wosiewitz U, Mildenburger P, Thelen M, Meyer zum Büschenfelde KH (1990). "Analysis of radiolucent gallstones by computed tomography for in vivo estimation of stone components". Eur J Clin Invest. 20 (4): 475–8. doi:10.1111/j.1365-2362.1990.tb01887.x. PMID 2121509.

[BolligerOesterhelweg2009-22] Bolliger, Stephan A.; Oesterhelweg, Lars; Spendlove, Danny; Ross, Steffen; Thali, Michael J. (2009). "Is Differentiation of Frequently Encountered Foreign Bodies in Corpses Possible by Hounsfield Density Measurement?". Journal of Forensic Sciences. 54 (5): 1119–1122. doi:10.1111/j.1556-4029.2009.01100.x. ISSN 0022-1198. PMID 19627414.

[23] scape >Adrenal Adenoma Imaging. Author: Perry J Horwich. Chief Editor: Eugene C Lin. Updated: Apr 21, 2011

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@@ Line 2: / Line 2: @@
 ==Definition==
-The Hounsfield unit (HU) scale is a linear transformation of the original linear attenuation coefficient measurement into one in which the [[radiodensity]] of [[distilled water]] at standard [[pressure]] and [[temperature]] ([[Standard conditions for temperature and pressure|STP]]) is defined as zero Hounsfield units (HU), while the  radiodensity of [[air]] at STP is defined as −1000 HU. In a [[voxel]] with average [[linear attenuation coefficient]] <math>\mu</math>, the corresponding HU value is therefore given by:
+The Hounsfield unit (HU) scale is a linear transformation of the original linear attenuation coefficient measurement into one in which the [[radiodensity]] of [[distilled water]] at standard [[pressure]] and [[temperature]] ([[Standard conditions for temperature and pressure|STP]]) is defined as zero Hounsfield units (HU), while the radiodensity of [[air]] at STP is defined as −1000 HU. In a [[voxel]] with average [[linear attenuation coefficient]] <math>\mu</math>, the corresponding HU value is therefore given by:
 <math>HU = 1000\times\frac{\mu - \mu_{\textrm{water}}}{\mu_{\textrm{water}} - \mu_{\textrm{air}}}</math>
@@ Line 35: / Line 35: @@
 | Cortical || +1800 to +1900<ref name="BirurPatrick2017"/>
 |-
-|rowspan=3| [[Subdural hematoma]] || First hours || +75 to +100<ref name="Rao2016">Fig 3 in: {{cite journal|last1=Rao|first1=Murali Gundu|title=Dating of Early Subdural Haematoma: A Correlative Clinico-Radiological Study|journal=Journal of Clinical and Diagnostic Research|volume=10|issue=4|pages=HC01–5|year=2016|issn=2249782X|doi=10.7860/JCDR/2016/17207.7644|pmid=27190831|pmc=4866129}}</ref>
+|rowspan=3| [[Subdural hematoma]] || First hours || +75 to +100<ref name="Rao2016">Fig 3 in: {{cite journal|last1=Rao|first1=Murali Gundu|title=Dating of Early Subdural Haematoma: A Correlative Clinico-Radiological Study|journal=Journal of Clinical and Diagnostic Research|volume=10|issue=4|pages=HC01–5|year=2016|issn=2249-782X|doi=10.7860/JCDR/2016/17207.7644|pmid=27190831|pmc=4866129}}</ref>
 |-
 | After 3 days || +65 to +85<ref name="Rao2016"/>
 |-
-| After 10-14 days || +35 to +40<ref>{{cite web|url=https://radiopaedia.org/articles/subdural-haemorrhage|author=Dr Rohit Sharma and A.Prof Frank Gaillard|accessdate=2018-08-14|website=[[Radiopaedia]]|title=Subdural haemorrhage}}</ref>
+| After 10–14 days || +35 to +40<ref>{{cite web|url=https://radiopaedia.org/articles/subdural-haemorrhage|author=Dr Rohit Sharma|author2=A.Prof Frank Gaillard|name-list-style=amp|accessdate=2018-08-14|website=[[Radiopaedia]]|title=Subdural haemorrhage}}</ref>
 |-
-|rowspan=2| Other [[blood]] || Unclotted || +13<ref name=fosbinder2011>[https://books.google.com/books?id=jRVg5ilM1UEC&pg=PA263 Page 263] in: {{cite book|title=Essentials of Radiologic Science|author=Robert Fosbinder, Denise Orth|publisher=Lippincott Williams & Wilkins|year=2011|isbn=9780781775540}}</ref> to +50<ref>[https://books.google.com/books?id=Bif0zpmEWtAC&pg=SA20-PA17 page 20.17] in: {{cite book|title=Radiology of the Chest and Related Conditions|author=F W Wright|publisher=CRC Press|year=2001|isbn=9780415281416}}</ref>
+|rowspan=2| Other [[blood]] || Unclotted || +13<ref name=fosbinder2011>[https://books.google.com/books?id=jRVg5ilM1UEC&pg=PA263 Page 263] in: {{cite book|title=Essentials of Radiologic Science|author=Robert Fosbinder|author2=Denise Orth|publisher=Lippincott Williams & Wilkins|year=2011|isbn=9780781775540}}</ref> to +50<ref>[https://books.google.com/books?id=Bif0zpmEWtAC&pg=SA20-PA17 page 20.17] in: {{cite book|title=Radiology of the Chest and Related Conditions|author=F W Wright|publisher=CRC Press|year=2001|isbn=9780415281416}}</ref>
 |-
-| [[Coagulation|Clotted]] || +50<ref name=fast2006>[https://books.google.com/books?id=4HaPJYaXXSAC&pg=PA17 page 17] in: {{cite book|title=Navigating the Adult Spine: Bridging Clinical Practice and Neuroradiology|author=Dr. Avital Fast, Dorith Goldsher|publisher=Demos Medical Publishing|year=2006|isbn=9781934559741}}</ref> to +75<ref name=fosbinder2011/><ref name=fast2006/>
+| [[Coagulation|Clotted]] || +50<ref name=fast2006>[https://books.google.com/books?id=4HaPJYaXXSAC&pg=PA17 page 17] in: {{cite book|title=Navigating the Adult Spine: Bridging Clinical Practice and Neuroradiology|author=Dr. Avital Fast|author2=Dorith Goldsher|publisher=Demos Medical Publishing|year=2006|isbn=9781934559741}}</ref> to +75<ref name=fosbinder2011/><ref name=fast2006/>
 |-
-|rowspan=2| [[Pleural effusion]] || [[Transudate]] || +2 to +15 <ref name="CulluKalemci2013">{{cite journal|last1=Cullu|first1=Nesat|last2=Kalemci|first2=Serdar|last3=Karakas|first3=Omer|last4=Eser|first4=Irfan|last5=Yalcin|first5=Funda|last6=Boyaci|first6=Fatma Nurefsan|last7=Karakas|first7=Ekrem|title=Efficacy of CT in diagnosis of transudates and exudates in patients with pleural effusion|journal=Diagnostic and Interventional Radiology|volume=20|issue=2|pages=116–20|year=2013|issn=13053825|doi=10.5152/dir.2013.13066|pmid=24100060|pmc=4463296}}</ref>
+|rowspan=2| [[Pleural effusion]] || [[Transudate]] || +2 to +15 <ref name="CulluKalemci2013">{{cite journal|last1=Cullu|first1=Nesat|last2=Kalemci|first2=Serdar|last3=Karakas|first3=Omer|last4=Eser|first4=Irfan|last5=Yalcin|first5=Funda|last6=Boyaci|first6=Fatma Nurefsan|last7=Karakas|first7=Ekrem|title=Efficacy of CT in diagnosis of transudates and exudates in patients with pleural effusion|journal=Diagnostic and Interventional Radiology|volume=20|issue=2|pages=116–20|year=2013|issn=1305-3825|doi=10.5152/dir.2013.13066|pmid=24100060|pmc=4463296}}</ref>
 |-
 | [[Exudate]] || +4 to +33<ref name="CulluKalemci2013"/>
 |-
 |rowspan=7| Other fluids || [[Chyle]]
-| −30<ref>[https://books.google.com/books?id=QmLNBQAAQBAJ&pg=PA342 Page 342] in: {{cite book|title=Multi-Detector CT Imaging: Principles, Head, Neck, and Vascular Systems, Volume 1|author=Luca Saba, Jasjit S. Suri|publisher=CRC Press|year=2013|isbn=9781439893845}}</ref>
+| −30<ref>[https://books.google.com/books?id=QmLNBQAAQBAJ&pg=PA342 Page 342] in: {{cite book|title=Multi-Detector CT Imaging: Principles, Head, Neck, and Vascular Systems, Volume 1|author=Luca Saba|author2=Jasjit S. Suri|publisher=CRC Press|year=2013|isbn=9781439893845}}</ref>
 |-
 |[[Water]]
@@ Line 65: / Line 65: @@
 |-
 | [[Abscess]] / [[Pus]]
-| 0<ref name=ecr>{{cite journal|url=http://pdf.posterng.netkey.at/download/index.php?module=get_pdf_by_id&poster_id=119826|title=Liver abscesses: where do they come from?A review of the main types of liver abscesses and the correlation between their causes and the radiologic findings|author=P. Sanchez de Medina Alba, C. Santos Montón, N. Calvo, K. El Karzazi, T. González de la Huebra Labrador, R. Corrales, N. Alegre Borge; Salamanca/ES|doi=10.1594/ecr2014/C-1927|website=ECR 2014|year=2014}}</ref> or +20<ref name="SasakiMiyata2014">{{cite journal|last1=Sasaki|first1=Toru|last2=Miyata|first2=Rie|last3=Hatai|first3=Yoshiho|last4=Makita|first4=Kohzoh|last5=Tsunoda|first5=Koichi|title=Hounsfield unit values of retropharyngeal abscess-like lesions seen in Kawasaki disease|journal=Acta Oto-Laryngologica|volume=134|issue=4|year=2014|pages=437–440|issn=0001-6489|doi=10.3109/00016489.2013.878475|pmid=24512428}}</ref>, to +40<ref name="SasakiMiyata2014"/> or +45<ref name=ecr/>
+| 0<ref name=ecr>{{cite journal|url=http://pdf.posterng.netkey.at/download/index.php?module=get_pdf_by_id&poster_id=119826|title=Liver abscesses: where do they come from?A review of the main types of liver abscesses and the correlation between their causes and the radiologic findings|author=P. Sanchez de Medina Alba|author2=C. Santos Montón|author3=N. Calvo|author4=K. El Karzazi|author5=T. González de la Huebra Labrador|author6=R. Corrales|author7=N. Alegre Borge|author8=Salamanca/ES.|doi=10.1594/ecr2014/C-1927|website=ECR 2014|year=2014}}</ref> or +20,<ref name="SasakiMiyata2014">{{cite journal|last1=Sasaki|first1=Toru|last2=Miyata|first2=Rie|last3=Hatai|first3=Yoshiho|last4=Makita|first4=Kohzoh|last5=Tsunoda|first5=Koichi|title=Hounsfield unit values of retropharyngeal abscess-like lesions seen in Kawasaki disease|journal=Acta Oto-Laryngologica|volume=134|issue=4|year=2014|pages=437–440|issn=0001-6489|doi=10.3109/00016489.2013.878475|pmid=24512428}}</ref> to +40<ref name="SasakiMiyata2014"/> or +45<ref name=ecr/>
 |-
 | [[Mucus]]
-| 0<ref>{{Cite journal|url=http://medind.nic.in/ibn/t06/i2/ibnt06i2p191.pdf|title=Mucocoele Of The Appendix|author=K SAGGAR, A AHLUWALIA, P SANDHU, V KALIA|journal=Ind J Radiol Imag|year=2006|volume=16|issue=2}}</ref> - 130<ref name="GaetaVinci2001">{{cite journal|last1=Gaeta|first1=Michele|last2=Vinci|first2=Sergio|last3=Minutoli|first3=Fabio|last4=Mazziotti|first4=Silvio|last5=Ascenti|first5=Giorgio|last6=Salamone|first6=Ignazio|last7=Lamberto|first7=Salvatore|last8=Blandino|first8=Alfredo|title=CT and MRI findings of mucin-containing tumors and pseudotumors of the thorax: pictorial review|journal=European Radiology|volume=12|issue=1|year=2001|pages=181–189|issn=0938-7994|doi=10.1007/s003300100934|pmid=11868096}}</ref> ("high attenuating" at over 70 HU)<ref>{{cite journal|title=High-Attenuation Mucus Impaction in Patients With Allergic Bronchopulmonary Aspergillosis: Objective Criteria on High-Resolution Computed Tomography and Correlation With Serologic Parameters|author=Subash S Phuyal, Mandeep Kumar MK Garg, Ritesh R Agarwal, Pankaj P Gupta, Arunaloke A Chakrabarti, Manavjit Singh MS Sandhu, Niranjan N Khandelwal|date=2015-09-02|journal=Current Problems in Diagnostic Radiology}}</ref><ref name="AgarwalSehgal2016">{{cite journal|last1=Agarwal|first1=Ritesh|last2=Sehgal|first2=Inderpaul Singh|last3=Dhooria|first3=Sahajal|last4=Aggarwal|first4=Ashutosh|title=Radiologic Criteria for the Diagnosis of High-Attenuation Mucus in Allergic Bronchopulmonary Aspergillosis|journal=Chest|volume=149|issue=4|year=2016|pages=1109–1110|issn=00123692|doi=10.1016/j.chest.2015.12.043|pmid=27055707}}</ref>
+| 0<ref>{{Cite journal|url=http://medind.nic.in/ibn/t06/i2/ibnt06i2p191.pdf|title=Mucocoele Of The Appendix|author=K SAGGAR, A AHLUWALIA|author2=P SANDHU, V KALIA|journal=Ind J Radiol Imag|year=2006|volume=16|issue=2}}</ref> - 130<ref name="GaetaVinci2001">{{cite journal|last1=Gaeta|first1=Michele|last2=Vinci|first2=Sergio|last3=Minutoli|first3=Fabio|last4=Mazziotti|first4=Silvio|last5=Ascenti|first5=Giorgio|last6=Salamone|first6=Ignazio|last7=Lamberto|first7=Salvatore|last8=Blandino|first8=Alfredo|title=CT and MRI findings of mucin-containing tumors and pseudotumors of the thorax: pictorial review|journal=European Radiology|volume=12|issue=1|year=2001|pages=181–189|issn=0938-7994|doi=10.1007/s003300100934|pmid=11868096}}</ref> ("high attenuating" at over 70 HU)<ref>{{cite journal|title=High-Attenuation Mucus Impaction in Patients With Allergic Bronchopulmonary Aspergillosis: Objective Criteria on High-Resolution Computed Tomography and Correlation With Serologic Parameters|author=Subash S Phuyal|author2=Mandeep Kumar MK Garg|author3=Ritesh R Agarwal|author4=Pankaj P Gupta|author5=Arunaloke A Chakrabarti|author6=Manavjit Singh MS Sandhu|author7=Niranjan N Khandelwal|date=2015-09-02|journal=Current Problems in Diagnostic Radiology}}</ref><ref name="AgarwalSehgal2016">{{cite journal|last1=Agarwal|first1=Ritesh|last2=Sehgal|first2=Inderpaul Singh|last3=Dhooria|first3=Sahajal|last4=Aggarwal|first4=Ashutosh|title=Radiologic Criteria for the Diagnosis of High-Attenuation Mucus in Allergic Bronchopulmonary Aspergillosis|journal=Chest|volume=149|issue=4|year=2016|pages=1109–1110|issn=0012-3692|doi=10.1016/j.chest.2015.12.043|pmid=27055707}}</ref>
 |-
 |rowspan=8| [[Parenchyma]] || [[Lung]]
-| −700 to −600<ref>[https://books.google.com/books?id=IJwZHPrDQYUC&pg=PA379 Page 379] in: {{cite book|title=Cardiopulmonary Imaging|volume=4|author=Ella A. Kazerooni, Barry H. Gross|publisher=Lippincott Williams & Wilkins|year=2004|isbn=9780781736558}}</ref>
+| −700 to −600<ref>[https://books.google.com/books?id=IJwZHPrDQYUC&pg=PA379 Page 379] in: {{cite book|title=Cardiopulmonary Imaging|volume=4|author=Ella A. Kazerooni|author2=Barry H. Gross|publisher=Lippincott Williams & Wilkins|year=2004|isbn=9780781736558}}</ref>
 |-
 | [[Kidney]]
@@ Line 77: / Line 77: @@
 |-
 | [[Liver]]
-| 60 ± 6<ref>[https://books.google.com/books?id=62jMOh67D8UC&pg=PA210 page 210] in: {{cite book|title=Hepatology, Principles and Practice: History, Morphology, Biochemistry, Diagnostics, Clinic, Therapy|author=Erwin Kuntz, Hans-Dieter Kuntz|publisher=Springer Science & Business Media|year=2006|isbn=9783540289777}}</ref>
+| 60 ± 6<ref>[https://books.google.com/books?id=62jMOh67D8UC&pg=PA210 page 210] in: {{cite book|title=Hepatology, Principles and Practice: History, Morphology, Biochemistry, Diagnostics, Clinic, Therapy|author=Erwin Kuntz|author2=Hans-Dieter Kuntz|publisher=Springer Science & Business Media|year=2006|isbn=9783540289777}}</ref>
 |-
 | [[Lymph node]]s
@@ Line 87: / Line 87: @@
 | [[Thymus]]
 |
-*+20 to +40 in children<ref name=givel2012>[https://books.google.se/books?id=AsTcBQAAQBAJ&pg=PT488 Page 488] in: {{cite book|title=Surgery of the Thymus: Pathology, Associated Disorders and Surgical Technique|author=Jean-Claude Givel, Marco Merlini, David B. Clarke, Michael Dusmet|publisher=Springer Science & Business Media|year=2012|isbn=9783642710766}}</ref>
+*+20 to +40 in children<ref name=givel2012>[https://books.google.se/books?id=AsTcBQAAQBAJ&pg=PT488 Page 488] in: {{cite book|title=Surgery of the Thymus: Pathology, Associated Disorders and Surgical Technique|author=Jean-Claude Givel|author2=Marco Merlini|author3=David B. Clarke|author4=Michael Dusmet|publisher=Springer Science & Business Media|year=2012|isbn=9783642710766}}</ref>
 *+20 to +120 in adolescents<ref name=givel2012/>
 |-
@@ Line 96: / Line 96: @@
 | +37 to +45
 |-
-|rowspan=2| [[Gallstone]] || Cholesterol stone || +30 to +100<ref name="pmid2121509">{{cite journal|vauthors=Rambow A, Staritz M, Wosiewitz U, Mildenburger P, Thelen M, Meyer zum Büschenfelde KH| title=Analysis of radiolucent gallstones by computed tomography for in vivo estimation of stone components | journal=Eur J Clin Invest | year= 1990 | volume= 20 | issue= 4 | pages= 475–8 | pmid=2121509 | doi= 10.1111/j.1365-2362.1990.tb01887.x| pmc= }} </ref>
+|rowspan=2| [[Gallstone]] || Cholesterol stone || +30 to +100<ref name="pmid2121509">{{cite journal|vauthors=Rambow A, Staritz M, Wosiewitz U, Mildenburger P, Thelen M, Meyer zum Büschenfelde KH| title=Analysis of radiolucent gallstones by computed tomography for in vivo estimation of stone components | journal=Eur J Clin Invest | year= 1990 | volume= 20 | issue= 4 | pages= 475–8 | pmid=2121509 | doi= 10.1111/j.1365-2362.1990.tb01887.x| pmc= }}</ref>
 |-
 | Bilirubin stone || +90 to +120<ref name="pmid2121509"/>
 |-
-|rowspan=7| [[Foreign body]]<ref name="BolligerOesterhelweg2009">{{cite journal|last1=Bolliger|first1=Stephan A.|last2=Oesterhelweg|first2=Lars|last3=Spendlove|first3=Danny|last4=Ross|first4=Steffen|last5=Thali|first5=Michael J.|title=Is Differentiation of Frequently Encountered Foreign Bodies in Corpses Possible by Hounsfield Density Measurement?|journal=Journal of Forensic Sciences|volume=54|issue=5|year=2009|pages=1119–1122|issn=00221198|doi=10.1111/j.1556-4029.2009.01100.x|pmid=19627414}}</ref>
+|rowspan=7| [[Foreign body]]<ref name="BolligerOesterhelweg2009">{{cite journal|last1=Bolliger|first1=Stephan A.|last2=Oesterhelweg|first2=Lars|last3=Spendlove|first3=Danny|last4=Ross|first4=Steffen|last5=Thali|first5=Michael J.|title=Is Differentiation of Frequently Encountered Foreign Bodies in Corpses Possible by Hounsfield Density Measurement?|journal=Journal of Forensic Sciences|volume=54|issue=5|year=2009|pages=1119–1122|issn=0022-1198|doi=10.1111/j.1556-4029.2009.01100.x|pmid=19627414}}</ref>
 || Windowpane glass || +500
 |-
@@ Line 135: / Line 135: @@
 ==Notes==
-{{reflist}}
+{{Reflist}}
 ==External links==
@@ Line 143: / Line 143: @@
 * [https://www.researchgate.net/publication/24234798_Imaging_of_deep_brain_stimulation_leads_using_extended_Hounsfield_unit_CT Imaging of deep brain stimulation leads using extended Hounsfield unit CT. Stereotact Funct Neurosurg. 2009;87(3):155-60. doi: 10.1159/000209296]
-[[Category:Radiology]]
 __FORCETOC__
+[[Category:Radiology]]