CLINICAL IMAGING 1992;16:277-278
277
EDITORIAL
RADIOLOGY OF THE PLEURAL FISSURES: AN HISTORICAL PERSPECTIVE SHEILA D. DAVIS,
MD
The interlobar fissures have long been recognized as important landmarks in identifying pulmonary lobar anatomy. As Sofranik et al. (1)point out in their review article, a clear understanding of how the fissures may be imaged on plain radiographic and computed tomographic (CT) studies is essential for correctly localizing parenchymal or pleural pathology. The normal appearance and variations of the fissures, as well as the frequency with which they may be incomplete, have been described and tabulated by various investigators over the past 40 years (z-5). Radiographic-anatomic correlation, often aided by the instillation of contrast-media saturated paper (a), wires, bags of water (5), or barium (6) into the fissures, has revealed that these structures are undulating surfaces. Proto and Speckman (7) suggested that the major fissures are “propellar-like” in their configuration, with “lateral facing” of the convex suprahilar portions and “medial facing” of the more concave infrahilar portions. Raasch et al. (5) concurred with these observations except that, for unclear reasons, they found that the infrahilar aspect of the right major fissure is usually “medial facing.” It is generally agreed that the minor fissure is upwardly convex and that the anterior aspect is usually lower than the posterior aspect (5). Understanding these relationships has proven to be of value in explaining some potentially confusing findings on chest radiographs. On the frontal projection, curving contours representing the “superolateral” (6)and “superomedial” (6,8) aspects of the
From the Department of Radiology, The New York Hospital-Cornell Medical Center, New York, New York. Address reprint requests to: Sheila D. Davis, MD, Department of Radiology, The New York Hospital-Cornell Medical Center, 525 East 68th St., New York, NY 10021. Received January 1992. 0 1992 by Elsevier Science Publishing Co., Inc. 655 Avenue of the Americas. New York,NY 10010 0899-70?1/92/$5.00
major fissures can occasionally be recognized. Undulation, as well as occasional incompleteness, readily accounts for the fact that fissures are infrequently seen along their entire length on frontal or lateral radiographs (7,9). In some cases, apparent extension of the minor fissue behind the right major fissure on the lateral view is explained by tangential visualization of the lateral aspect of the minor fissure, as it is projected over the medial edge of a “laterally facing” major fissure (7). It is also evident that a lesion in the vicinity of a fissure on the lateral projection might be falsely localized. For example, a lesion projected anterior to the major fissure may actually be in the right lower lobe or a lesion projected below the minor fissure may actually be in the right upper lobe (7). Finally, it is now recognized that tangential imaging of the major fissure may give the false impression of volume loss, with apparent posterior displacement on the lateral view or apparent inferior displacement on the frontal view (7,8). The presence of interlobar fluid, fat, or connective tissue may highlight the presence of complete or incomplete fissures (3, 5,6).In normal patients, it has been observed that intrafissural fat along the lateral insertion of the major fissures may at least in part account for the curving contour of the“superolatera1” fissure (6).Recently, it has been noted that intrafissural fat along the inferior aspect of the major fissure may account for triangular supradiaphragmatic opacity on the lateral view (10)and occasional indistinctness of the middle third of the diaphragm on the frontal view (7,10). Complexities of the three-dimensional configuration of fissural surfaces in vivo are even more clearly delineated on axial computed tomographic (CT) scans. A decade ago, studies utilizing standard lo-mm collimation scans showed that the major fissures may be appreciated as a hypovascular band, a narrow line or, least often, as a dense band (11-13). The minor fissure was described as a triangular,
278
CLINICAL IMAGING VOL. 18, NO. 4
DAVIS
rounded, or oval avascular zone, usually imaged over one or two CT sections (11-14). Subsequently, with increasing use of thin-section scans, it became evident that the CT appearance of the fissures is largely determined by the collimation employed and the level at which the fissures are imaged (15). Relatively vertical portions of the fissures are expected to appear as a thin line; relatively oblique portions of the fissures should appear as a line or dense band more frequently on narrow collimation than on routine scans, due to a lesser degree of volume averaging on the thin sections. With use of narrow collimation, there is a greater degree of precision in localizing pulmonary lesions with respect to the fissures. The extent of fissural completeness is also more clearly assessed on thin-section scans. Berkmen et al. (16), reviewing thin-section scans in 40 patients, described two major configurations for the minor fissure, depending on whether the highest portion of the middle lobe upper surface is medially (Type I) or laterally (Type II) situated. Incompleteness or absence of the minor fissure was seen in 31 (78%)patients and incompleteness was generally present along the medial aspect of the fissure. These results were in accord with previous anatomic studies. Frija et al. (17) have observed two other possible appearances for the minor fissure. A sagittal orientation has also been described (18). A recent article by Glazer et al. (19) reported analysis of the major fissures on thin-section (&mm collimation) scans in 50 patients. These fissures were better evaluated on thin-section than on routine (lo-mm collimation) scans. Incompleteness was observed in 32 (64%) cases for the right major fissure and in 26 (52%)cases for the left major fissure. As for the minor fissure, incompleteness was usually found along the medial aspect of the major fissures, again in accord with previous anatomic studies. Accurate depiction of fissural anatomy on standard and thin-section CT scans is clearly of clinical importance. Ambiguities on the chest radiograph, arising from normal variations of the fissures, may be readily clarified at CT. Familiarity with the usual CT appearance for displaced fissures or “neofissures” following pulmonary resection is essential for optimal postoperative evaluation of patients (20). Precise localization of lesions is often important in determining the optimal approach for diagnosis (e.g., fiberoptic bronchoscopy, transthoracic needle biopsy) or surgical resection (19). By revealing possible transfissural extension of neoplasm, CT may also help
determine whether pneumonectomy or lobectomy is required (21). Further studies are needed in order to better define the clinical applications of CT, particularly thin-section CT, in demonstrating how the fissures may be affected by parenchymal or pleural pathology.
REFERENCES 1. Sofranik RM, Gross BH, Spizarny DL. Radiology of the pleural fissures. Clin Imaging 1992;16:281-229. 2. Kent EM, Blades B. The surgical anatomy of the pulmonary lobes. J Thorac
Surg 1942;12:18-30.
3. Medlar EM. Variations 57:723-725. 4. Yamashita Igaku-Shoin,
in interlobar
fissures.
H. Roentgenologic Anatomy 1978, pp. 46-54.
AJR
1947;
of the Lung. Tokyo:
5. Raasch BN, Carsky EW, Lane EJ, O’Callaghan JP, Heitzman ER. Radiographic anatomy of the interlobar specimens. AJR 1982;138:1043-1049.
fissures: a study of 100
8. Proto AV, Ball JB Jr. The superolateral
major fissures.
AJR
i983;140:431-437.
7. Proto AV, Speckman
JM. The left lateral chest. Med Radiogr Photog 1979;55:30-74.
radiograph
of the
8. Fisher MS. Significance
of a visible major fissure on the frontal AJR 1981;137:577-580.
chest radiograph.
9. Heitzman ER. Diseases of the pleura. In: The Lung RadiologicPathologic Correlations. St. Louis: Mosby, 1984,pp. 516-518. 10. Gale ME, Grett WL. Intrafissural fat: CT correlation with chest radiography.
Radiology
1986;160:333-336.
11. Marks BW, Kuhns LR. Identification with computed
tomography.
Radiology
of the pleural fissures 1982;143:139-141.
12. Frija J, Schmit P, Katz M, Vadrot D, Laval-Jean&t
M. Computed normal anatomy.
tomography of the pulmonary fissures: J Comput Assist Tomogr 1982;6:1069-1074.
13. Proto AV, Ball JB. Computed tomography of the major and minor fissures. AJR 1983;140:439-448. 14. Goodman LR, Golkow RS, Steiner RM, et al. The right midlung window: a potential source of error in computed tomography of the lung. Radiology 1982;143:135-138.
15. Chasen MH, McCarthy MJ, Gilliland JD, Floyd JL. Concepts in computed tomography 1986;6:793-832.
of
the
thorax.
Radiographics
16. Berkmen YM, Auh YH, Davis SD, Kazam E. Anatomy of the minor fissure: evaluation 1989;170:647-651.
with
thin-section
CT. Radiology
17. Frija J, Yana C, Laval-Jeantet evaluation 571-572.
with
18. Gross BH, Spizarny the anterior minor 1988;166:717-719.
M. Anatomy of the minor fissure: thin-section CT. Radiology 1989;173: DL, Granke DS. Sagittal orientation of fissure: radiography and CT. Radiology
19. Glazer HS, Anderson
DJ, DiCroce JJ, et al. Anatomy of the major fissure: evaluation with standard and thin-section CT. Radiology 1991;180:839-844.
20. Mahoney MC, Shipley RT. Neofissure after right upper lobectomy: radiographic
evaluation.
Radiology
1988;166:721-723.
21. Quint LE, Glazer GM, Orringer MB. Central lung masses: prediction with CT of need of pneumonectomy Radiology 1987;165:735-738.
versus lobectomy.
277
EDITORIAL
RADIOLOGY OF THE PLEURAL FISSURES: AN HISTORICAL PERSPECTIVE SHEILA D. DAVIS,
MD
The interlobar fissures have long been recognized as important landmarks in identifying pulmonary lobar anatomy. As Sofranik et al. (1)point out in their review article, a clear understanding of how the fissures may be imaged on plain radiographic and computed tomographic (CT) studies is essential for correctly localizing parenchymal or pleural pathology. The normal appearance and variations of the fissures, as well as the frequency with which they may be incomplete, have been described and tabulated by various investigators over the past 40 years (z-5). Radiographic-anatomic correlation, often aided by the instillation of contrast-media saturated paper (a), wires, bags of water (5), or barium (6) into the fissures, has revealed that these structures are undulating surfaces. Proto and Speckman (7) suggested that the major fissures are “propellar-like” in their configuration, with “lateral facing” of the convex suprahilar portions and “medial facing” of the more concave infrahilar portions. Raasch et al. (5) concurred with these observations except that, for unclear reasons, they found that the infrahilar aspect of the right major fissure is usually “medial facing.” It is generally agreed that the minor fissure is upwardly convex and that the anterior aspect is usually lower than the posterior aspect (5). Understanding these relationships has proven to be of value in explaining some potentially confusing findings on chest radiographs. On the frontal projection, curving contours representing the “superolateral” (6)and “superomedial” (6,8) aspects of the
From the Department of Radiology, The New York Hospital-Cornell Medical Center, New York, New York. Address reprint requests to: Sheila D. Davis, MD, Department of Radiology, The New York Hospital-Cornell Medical Center, 525 East 68th St., New York, NY 10021. Received January 1992. 0 1992 by Elsevier Science Publishing Co., Inc. 655 Avenue of the Americas. New York,NY 10010 0899-70?1/92/$5.00
major fissures can occasionally be recognized. Undulation, as well as occasional incompleteness, readily accounts for the fact that fissures are infrequently seen along their entire length on frontal or lateral radiographs (7,9). In some cases, apparent extension of the minor fissue behind the right major fissure on the lateral view is explained by tangential visualization of the lateral aspect of the minor fissure, as it is projected over the medial edge of a “laterally facing” major fissure (7). It is also evident that a lesion in the vicinity of a fissure on the lateral projection might be falsely localized. For example, a lesion projected anterior to the major fissure may actually be in the right lower lobe or a lesion projected below the minor fissure may actually be in the right upper lobe (7). Finally, it is now recognized that tangential imaging of the major fissure may give the false impression of volume loss, with apparent posterior displacement on the lateral view or apparent inferior displacement on the frontal view (7,8). The presence of interlobar fluid, fat, or connective tissue may highlight the presence of complete or incomplete fissures (3, 5,6).In normal patients, it has been observed that intrafissural fat along the lateral insertion of the major fissures may at least in part account for the curving contour of the“superolatera1” fissure (6).Recently, it has been noted that intrafissural fat along the inferior aspect of the major fissure may account for triangular supradiaphragmatic opacity on the lateral view (10)and occasional indistinctness of the middle third of the diaphragm on the frontal view (7,10). Complexities of the three-dimensional configuration of fissural surfaces in vivo are even more clearly delineated on axial computed tomographic (CT) scans. A decade ago, studies utilizing standard lo-mm collimation scans showed that the major fissures may be appreciated as a hypovascular band, a narrow line or, least often, as a dense band (11-13). The minor fissure was described as a triangular,
278
CLINICAL IMAGING VOL. 18, NO. 4
DAVIS
rounded, or oval avascular zone, usually imaged over one or two CT sections (11-14). Subsequently, with increasing use of thin-section scans, it became evident that the CT appearance of the fissures is largely determined by the collimation employed and the level at which the fissures are imaged (15). Relatively vertical portions of the fissures are expected to appear as a thin line; relatively oblique portions of the fissures should appear as a line or dense band more frequently on narrow collimation than on routine scans, due to a lesser degree of volume averaging on the thin sections. With use of narrow collimation, there is a greater degree of precision in localizing pulmonary lesions with respect to the fissures. The extent of fissural completeness is also more clearly assessed on thin-section scans. Berkmen et al. (16), reviewing thin-section scans in 40 patients, described two major configurations for the minor fissure, depending on whether the highest portion of the middle lobe upper surface is medially (Type I) or laterally (Type II) situated. Incompleteness or absence of the minor fissure was seen in 31 (78%)patients and incompleteness was generally present along the medial aspect of the fissure. These results were in accord with previous anatomic studies. Frija et al. (17) have observed two other possible appearances for the minor fissure. A sagittal orientation has also been described (18). A recent article by Glazer et al. (19) reported analysis of the major fissures on thin-section (&mm collimation) scans in 50 patients. These fissures were better evaluated on thin-section than on routine (lo-mm collimation) scans. Incompleteness was observed in 32 (64%) cases for the right major fissure and in 26 (52%)cases for the left major fissure. As for the minor fissure, incompleteness was usually found along the medial aspect of the major fissures, again in accord with previous anatomic studies. Accurate depiction of fissural anatomy on standard and thin-section CT scans is clearly of clinical importance. Ambiguities on the chest radiograph, arising from normal variations of the fissures, may be readily clarified at CT. Familiarity with the usual CT appearance for displaced fissures or “neofissures” following pulmonary resection is essential for optimal postoperative evaluation of patients (20). Precise localization of lesions is often important in determining the optimal approach for diagnosis (e.g., fiberoptic bronchoscopy, transthoracic needle biopsy) or surgical resection (19). By revealing possible transfissural extension of neoplasm, CT may also help
determine whether pneumonectomy or lobectomy is required (21). Further studies are needed in order to better define the clinical applications of CT, particularly thin-section CT, in demonstrating how the fissures may be affected by parenchymal or pleural pathology.
REFERENCES 1. Sofranik RM, Gross BH, Spizarny DL. Radiology of the pleural fissures. Clin Imaging 1992;16:281-229. 2. Kent EM, Blades B. The surgical anatomy of the pulmonary lobes. J Thorac
Surg 1942;12:18-30.
3. Medlar EM. Variations 57:723-725. 4. Yamashita Igaku-Shoin,
in interlobar
fissures.
H. Roentgenologic Anatomy 1978, pp. 46-54.
AJR
1947;
of the Lung. Tokyo:
5. Raasch BN, Carsky EW, Lane EJ, O’Callaghan JP, Heitzman ER. Radiographic anatomy of the interlobar specimens. AJR 1982;138:1043-1049.
fissures: a study of 100
8. Proto AV, Ball JB Jr. The superolateral
major fissures.
AJR
i983;140:431-437.
7. Proto AV, Speckman
JM. The left lateral chest. Med Radiogr Photog 1979;55:30-74.
radiograph
of the
8. Fisher MS. Significance
of a visible major fissure on the frontal AJR 1981;137:577-580.
chest radiograph.
9. Heitzman ER. Diseases of the pleura. In: The Lung RadiologicPathologic Correlations. St. Louis: Mosby, 1984,pp. 516-518. 10. Gale ME, Grett WL. Intrafissural fat: CT correlation with chest radiography.
Radiology
1986;160:333-336.
11. Marks BW, Kuhns LR. Identification with computed
tomography.
Radiology
of the pleural fissures 1982;143:139-141.
12. Frija J, Schmit P, Katz M, Vadrot D, Laval-Jean&t
M. Computed normal anatomy.
tomography of the pulmonary fissures: J Comput Assist Tomogr 1982;6:1069-1074.
13. Proto AV, Ball JB. Computed tomography of the major and minor fissures. AJR 1983;140:439-448. 14. Goodman LR, Golkow RS, Steiner RM, et al. The right midlung window: a potential source of error in computed tomography of the lung. Radiology 1982;143:135-138.
15. Chasen MH, McCarthy MJ, Gilliland JD, Floyd JL. Concepts in computed tomography 1986;6:793-832.
of
the
thorax.
Radiographics
16. Berkmen YM, Auh YH, Davis SD, Kazam E. Anatomy of the minor fissure: evaluation 1989;170:647-651.
with
thin-section
CT. Radiology
17. Frija J, Yana C, Laval-Jeantet evaluation 571-572.
with
18. Gross BH, Spizarny the anterior minor 1988;166:717-719.
M. Anatomy of the minor fissure: thin-section CT. Radiology 1989;173: DL, Granke DS. Sagittal orientation of fissure: radiography and CT. Radiology
19. Glazer HS, Anderson
DJ, DiCroce JJ, et al. Anatomy of the major fissure: evaluation with standard and thin-section CT. Radiology 1991;180:839-844.
20. Mahoney MC, Shipley RT. Neofissure after right upper lobectomy: radiographic
evaluation.
Radiology
1988;166:721-723.
21. Quint LE, Glazer GM, Orringer MB. Central lung masses: prediction with CT of need of pneumonectomy Radiology 1987;165:735-738.
versus lobectomy.
