The Value, Limitations, and Applications of Nuclear Dacryocystography

Mark Brown, Taher A. M. El Gammal, Malcolm N. Luxenberg, and Casimir Eubig

Nuclear dacryocystography is a simple, relatively harmless method of evaluating patients suspected of having abnormalities of the nasolacrimal drainage system. A drop of normal saline containing approxi- mately 100 #Ci of SS~Tc-pertechnetate is placed on the conjunctiva near the lateral canthus, and serial scintigrams are obtained as the pertechnetate flows along the tear strips, through the nasolacrimal drain- age system, into the nasal fossa. By using a pinhole collimator with a very small aperture (1 ram), the canaliculi, the nasolacrimal sac, and the nasolacrimal duct are readily visualized. When flow is impaired,

the site of obstruction can often be identified. Contrast dacryocystography provides similar infor- mation but requires the injection of contrast mate- rial directly into a canaliculus. Nuclear dacryocys- tograpby provides good functional assessment of nasolacrimal drainage but has serious shortcomings in defining pathologic anatomy. Contrast dacryocys- tography outlines the anatomy well but often misses minor obstructions. The two studies are comple- mentary and together provide an effective means of evaluating the nasolacrima! drainage system.

T HE PURPOSE of this article is to review our experience with over 250 nuclear

dacryocystograms and, from that experience, to draw some conclusions as to the value of the procedure, how it should be performed, and how it should be integrated with other diagnostic studies in the evaluation of obstructive disease of the lacrimal drainage system.

MATERIALS AND METHODS

Clinical Material

Nuclear dacryocystography (DCG) was developed at the Medical College of Georgia and has been used here since 1972) _3* Two-hundred sixty-three nuclear DCGs have been done during this period on patients with a broad spectrum of abnormalities of the nasolacrimal drainage system. Fifty- three of these patients had at least one contrast DCG. Approximately one-fourth of the patients who had nuclear DCGs had surgical or radiotherapeutic procedures as well.

Contrast DCG Techniques 4's Initially, the contrast DCGs were done by distention

macrodacryocystography using an oil-based contrast materi- al, ethiodol. Since 1979, we have modified the technique so that we now use biplane studies with two to one magnifica- tion and subtraction and the water-soluble contrast material, metrizamide (Amipaque).

*Trueblood JH, Rossomondo RM, Carlton WH: A method for microscintigraphic evaluation studies. U.S. Patent No. 3,863,623. February 4, 1975.

From the Departments of Radiology and Ophthalmology, Medical College of Georgia. Augusta, Ga.

Reprint requests should be addressed to Mark Brown, M.D., Department of Radiology, Medical College of Geor- gia, Augusta, Ga. 30912.

�9 1981 by Grune & Stratton, Inc. 0001 2998/81/1104-0003501.00/0

Nuclear DCG Techniques The techniques used have been previously described in

detail) 3 Briefly, a droplet of sterile normal saline containing approximately 100 uCi of 99mTc-pertechnetate is dropped onto the conjunctiva near the lateral canthus, and serial scintigrams are obtained every 30 sec for 5 rain. A pinhole collimator equipped with a very small aperture (usually 1 mm) is used because this sized aperture was found to provide the best balance between resolution and sensitivity. The contralateral asymptomatic eye is always done first. This familiarizes the patient with the procedure, provides a normal control for comparison, and costs little in terms of time, discomfort, or increased radiation. Although rarely clinically significant, unsuspected contralateral abnormali- ties are not unusual.

Modifications of this technique were made as new cameras were acquired and as we realized, with experience, the need for greater magnification, interventional maneuvers, and improved methods of immobilizing the patient. Descriptions of these modifications follow.

Micropinhole Collimators Our initial imaging system consisted of a Searle (Siemens)

HP camera and pinhole coltimator fitted with a special micropinhole aperture (diameter 1 mm at an angle of 80~ As we acquired other cameras with improved intrinsic reso- lution and different pinhole to crystal distances, we devel- oped a micropinhole collimator system that was modular so that apertures and cameras could be interchanged. An exam- ple of this is our micropinhole for the Ohio Nuclear (Techni- care) Sigma 420 gamma camera shown in Fig. 1. The camera manufacturer supplied a "blank" pinhole insert along with the standard pinhole collimator housing. A local machine shop then modified the insert to accept the micro- pinhole aperture as shown in the figure. The inserts used initially were manufac tu red by Dunn I n s t r u m e n t s ; t however, they have discontinued the manufacture of this

tD-I Model 350 Micropinhole for Searle scintillation camera. Dunn Instruments, Inc. 52 Colin P. Kelly Jr. Street, San Francisco, Calif. 94107.

250 Seminars in Nuclear Medicine, Vol. XI, No. 4 (October), 1981

NUCLEAR DACRYOCYSTOGRAPHY 251

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product. 6 Our new inserts were machined locally out of a lead brick. Since lead is very soft, these apertures must be handled with care.

Immobilization of the Patient

Another modification found to be very helpful was the use of an easily adjustable and comfortable head immobilizer. It is used with the patient seated in a chair to which a 6-in wide board that is approximately 30 in long is attached. A commercially available moldable, vacuum pillow that is filled with small radiolucent polystyrene beads* is placed between the patient's head and the board. The pillow is shaped to the contour of the head in front and the board behind. When air is evacuated from the pillow, the beads press against each other, and the pillow becomes a firm mold that holds both the head and. the.board. This limits move- ment yet is quite comfortable (Fig. 2).

Although we have had limited experience with infants and small children (6 cases), we feel that adequate studies can be obtaiaed by using the polystyrene pillow along with proper sedation and supine positioning.

Noninvasive Interventional Maneuvers

We frequently use several benign interventional maneu- vers to help clarify problems that develop during the perfor- mance of nuclear DCGs. These include the following. (1) "Closeup/remote images." These scintigrams are made with skin-to-collimator distances as little as 5 mm and as great as 5 cm. The former produces greatly magnified "high resolu- tion" images that are difficult to interpret unless combined

*Mold-and-Hold lmmobilizer/Positioner. Victoreen, Inc., 100 Voice Road, Carle Place, N.Y. 11514.

Fig. 2. Polystyrene moldable vacuum pillow. Note that it holds the head firmly and comfortably in front and the supporting board behind.

with more remote, low magnification images for anatomical orientation. (2) "Ocular lavage" is used in patients with obstruction to wash away confusing collections of radioactiv- ity on the lids or in the medial canthal region. The area is thoroughly cleansed with water and a gauze sponge. We often use the laboratory's emergency eye wash apparatus in order to distinguish what can from what cannot be washed away. This helps to differentiate radioactivity within the sac from radioactivity pooled about the inner canthus or inadver- tently spilled onto the lids. (3) "Sac compression." This maneuver is carried out by gently massaging the nasolacri- mal sac with the finger tip covered by a sterile gauze sponge. It is used to help evaluate sluggish flow in the nasolacrimal

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8 11

Fig. 3. Anatomy of the nasolacrimal drainage system. TM

(1) Puncture, (2) ascending segment of the superior canali- culus (~2 mm), (3) horizontal segment of the superior canaliculus (~9 ram), (4) common canaliculus (sinus of Maier and valve of Rosenmiiller), (5) nasolacrimal sac (~12 mm), (6) nasolacrimal duct (~17 mm), (7) medial extension of superior conjunctival fornix, (8) inferior tear strip, (9) medial canthus and caruncle, (10) inter sac distance, (11) lateral canthus, (12) inferior turbinate, (13) entrance to bony canal, (14) valve of Krause, (15) valve of Hasner.

252 BROWN ET AL.

duct. (4) "Artificial tearing." This technique is used to encourage the progression of the previously administered radiopertechnetate droplet through the drainage system, Three or four drops of sterile normal saline are placed in the lateral canthal region to achieve this effect.

RADIATION DOSIMETRY

Radiation to the lens from the nuclear DCG was studied extensively by Robertson et al. 7 Assuming unobstructed flow, they estimated that the lens received between 0.014 and 0.021 rads/100-150 /aCi of 99mTc-pertechnetate ad- ministered in a drop of normal saline placed on the conjunctiva. If flow was totally obstructed, a maximum theoretical dose of 0.402-0.604 rads/ radiopertechnetate drop was calculated. Similar dose estimates have been made by others. ~'2'8 Methods of delivering the radiopertechnetate

drops so that they contain approximately 100 ~tCi of 99rnyeo 4- have been described by several authors. 3,9

Contrast DCG using biplane magnification and subtraction techniques was found to deliver approximately 2 rads to the cornea (374 mrads/ anterior exposure; 112 mrads/lateral exposure; 4 biplane exposures/examination). Since the dose delivered to the lens is approximately equal to that delivered to the cornea, we estimate that in our department the lens receives about 100 times more radiation from contrast DCGs than it does from the nuclear DCGs.

TRANSIT TIMES

The anatomy of the nasolacrimal drainage system is schematically shown in Fig. 3. Flow

Fig. 4. Nuclear and roentgenographic anatomy as demonstrated in a patient (249-361) who has a chronic infection of the nasolacrimal drainage system of the left eye, probably due to a fungal infection. (A} The normal right eye 30 sec after instil lation of a radiopertechnetate droplet. Note the superior canaliculus (~), inferior canaliculus (T), nasolacrimal sac ( ~ ) , and duct (~--<). (BI The left eye 30 sec af ter instillation of the radiopertechnetate droplet. Note the radioactivity pooled in the medial canthal region (~) and the irregularit ies along the lateral aspect of the duct (( I ). (C) Contrast dacryocystogram showing the superior canaliculus (~), inferior canaliculus (T}, the superior tear strip (t), contrast media pooling in the inner canthus (7), the valve of Hasner at the distal end of a narrowed scarred duct ( * - - -~- ) , and contrast media spilling into the inferior meatus of the nasal fossa ( ~ | . (D) Left eye 5 min af ter B,

NUCLEAR DACRYOCYSTOGRAPHY 253

through this system has been studied extensively. Carlton et al., 2 in studies involving 28 normal patients, found the median transit time from administration of the radioactive tear until it reached the lacrimal sac to be 6 sec (range 4-23 sec) and the median transit time to the bottom of the duct to be 43 sec (range 4 323 sec). Brizel et al. 3 found that in 61 "normal" patients, activity appeared in the sac within 1 min in 94% of the studies and within 2 min in 100%. They also found that activity appeared in the duct within 2 min in 88% of these patients (in 8% it took more than 4 min) and that flow into the nasal fossa was often not demonstrable. Using computer analysis, Hurwitz et al. ]~ described 6 criteria for normal drainage times and reported the effects of changes in position, blinking, and vari- ous pathologic conditions.

With our techniques, we found the appear- ance time in the sac to be the only reliable parameter (normal <1.5 min; delayed 1.5-3 min; markedly delayed >3 min). The appear- ance time in the distal duct and nasal fossa were too variable to be used except to reinforce other observations. Figure 4A shows normal nasocri- mal drainage, while Fig. 4B represents a study in a patient with chronic infection.

CANALICULAR EVALUATION

Consistent visualization of individual canali- culi remains a problem. Although frequently well visualized and easily analyzed, canalicular flow is often obscured by confusing radioactivity pooled in the inner canthal region, the tear strips, and the conjunctival fornices. We find that the noninvasive interventional maneuvers

Fig. 5. Nuclear dacryocystography demonstrat ing the use of " 'c loseup/remote v iews" in a pat ient (251-986) who has bilateral duct ectasia and a dacryol i th in the left nasolacrimal sac (--*), (A) Standard magnification. The sac is just beginning to fill at 1.5 min. The fill ing defect produced by the stone ( ~ ) is diff icult to appreciate at this t ime. Note the radioact iv i ty in the inferior canaliculus (~) and in the shorter superior canaliculus (~). the inferior tear str ip (T), the superior tear str ip (~:). as well as the radiopertechnetate pooled in the medial canthal region (7), (B) One minute later, As more radioact iv i ty f lows into the sac, the fill ing defect produced by the stone is bet ter seen (--*), (C) Closaup v iew at 6.5 min showing the defect produced by the stone ( ~ ) , As the medial canthal (5) and inferior canalicular radioact iv i ty begins to clear, the superior canaliculus is bet ter visualized. (D) The remote v iew obtained 20 min af ter the radiopertechnetate was instilled into the left eye and 10 min after it was instilled into the r ight eye. The defect produced by the stone is poorly visualized but the dilatation of the ducts and the f low into the inferior meatus of the nasal fossa are now readily appreciated.

254 BROWN ET AL.

described earlier are frequently helpful. A radioactive marker is also useful in correlating the nuclear DCG findings with surface anato- my.

Problems relating to variable magnification are avoided by including the small amount of radioactivity left from the preliminary evalua- tion of the contralateral eye on the remote image of the "closeup/remote combination images" (Fig. 5). Although the distance between the nasolacrimal sacs varies from patient to patient, it is constant in a given patient and can be used to estimate the degree of magnification. Figures 6 and 7 show other clinical examples of nuclear DCGs.

CONTRAST VERSUS NUCLEAR DCG

The nuclear DCG is primarily a physiologic test that yields information about the way tears flow through the nasolacrimal drainage system. The contrast DCG is used primarily as an anatomical study and provides a detailed picture of the pathologic anatomy of an obstructed system. In most instances in which obstruction is suspected, we recommend the nuclear DCG as the initial radiographic study as it is simpler to Perform, causes less discomfort, and delivers much less radiation to the lens. When adequate information is not obtained or if confirmation is needed the contrast DCG is done. The combina- tion of the two studies almost always localizes

Fig. 6. Nuclear DCG demonstrat ing the use of "ocular lavage'" in a pat ient (010-231) w i th obstruct ion of the r ight nasolacrimal s a c . (A) One and one-half minutes af ter instil- lation of the radiopertechnetate droplet. Note that a small amount of radioact iv i ty has reached the sac (~), but most remains pooled in the medial canthal region (~) and in the superior ( t) and inferior (T) tear strips. (B) Remote v iew immediately af ter thorough cleansing of both eyes (P.L. - - post lavage). There has been no progress beyond the sac (5) on the right. Flow through the left nasolacrimal duct ( 4 ) was normal. The radiopertechnetate had been instilled into the r ight eye 11 rain and in the left eye 21 min prior to obtaining this image.

Fig. 7. Nuclear dacryocystogram (253-045) showing an unusually prominent sinus of Ar l t (~_).11 This normal variant is caused by bulging of the lateral wall of the tear sac just above the constr ict ion produced by the crossing split facia of the orbicularis muscle, the so-called valve of Krause (>--*). (A) One and one-half minutes after radioper- technetate instil lation. Note the radioact iv i ty pooled in the medial canthal region (~) and in the sac ( 4 ) . (B) Eleven and one-half minutes later. A small amount of radioact iv i ty is seen to have reached the distal duct and spilled into the inferior meatus of the nasal fossa (*--<).

NUCLEAR DACRYOCYSTOGRAPHY 255

Fig. 8. Unsuspected dacryol i th (207-351) associated w i th a nonobstruct ing stenosis of the proximal nasolacrimal duct. These studies of the asymptomat ic left eye where done as part of an evaluation for persistent epiphora on the right. (A and B) Closeup v iews obtained 30 sec and 10.5 min af ter the insti l lation of the radiopertechnetate droplet. Note the fill ing defect caused by the dacryoli th ( ~ ) , the radioact iv i ty pooled in the inner canthus (1), the stenot ic proximal duct ( ~ ) , and the normal distal duct (~-- ' ) . The lat ter filled 0nly af ter a delay of 10 min. (C) Remote v iew at 20 min. Note that almost all of the radiopertechnetate is in the distal duct (>~* ) leaving only a small amount in the inner canthal region (1) and sac. The filling defect caused by the stone is still discernible ( ~ ) . (D) Contrast dacryocystogram showing the dacryol i th ( ~ ) , the stenotic proximal duct ( 4 ) , the normal caliber of the distal duct (>-~) , and the contrast media that has spilled into the inferior meatus of the nasal fossa (~).

the obstruction. In no instance has a contrast DCG uncovered a significant abnormality when the nuclear DCG was normal. Neither test is particularly useful when the primary disease process involves the puncta or lids except to rule out a more distal or an unsuspected contralateral abnormality. Unsuspected abnormalities of the contralateral nasolacrimal system are not

uncommon but have rarely proven to be clini- cally significant. The contrast DCGs often missed minor obstructions that were apparent on the nuclear study, probably because the pressure used to inject the contrast media was sufficient to overcome the resistance of the obstruction.

The following lists summarize our opinions relative to the indications for these two studies.

256 BROWN ET AL.

Indications for Nuclear DCG

(1) To evaluate patients with complaints of epiphora in whom the etiology and site of obstruction cannot be determined from routine clinical tests.

(2) To document the presence or absence of nasolacrimal abnormalities at a given point in time.

(3) To evaluate postoperative patients with persistent tearing.

(4) To determine the status of the nasolacri- real system in patients with mass lesions of nearby structures before and after therapy.

(5) To perform physiologic or pharmacologic investigationsJ ~

Indications for Contrast DCG

(1) To define the pathologic anatomy of obstructive lesions of the nasolacrimal system.

(2) To evaluate known lesions, such as sinus tracts or fistulae, arising from the nasolacrimal system.

(3) To study those patients in whom a mass lesion (i.e., stone or tumor) of the nasolacrimal system is suspected.

(4) To evaluate patients with epiphora in whom fluid passes into the nose during irrigation but in whom no flow can be demonstrated by nuclear DCG.

Figures 8 and 9 illustrate the complementary roles of nuclear and contrast DCG.

Contraindications

In our 9-yr experience we know of no compli- cation that was ascribed to either nuclear or contrast dacryocystography. However, we do not perform contrast DCG in the presence of acute inflammatory processes. Hypersensitivity to the

Fig. 9. Disparate nuclear and contrast dacryocystographic f indings in a patient (272-396) w i th chronic dacryocysti t is. The nuclear DCG shows a functional obstruct ion in the midportion of the sac, whi le the contrast DCG shows the obstruct ion to be due to multiple post inf lammatory adhesions of the distal duct. (A) One minute and 30 sec after insti l lation of the radiopertechnetate droplet. Note the radioact iv i ty in the sac (~} and the inner canthal region (~}. (B) Sixteen minutes later fo l lowing "ocular lavage'" (P.L. - -post lavage). Note that the small amount of act iv i ty in the sac (~) could not be washed away and that it would not f low beyond this point. (C) The contrast DCG shows two stenot ic areas in the distal duct ( ~ ) . Note the pooling of the contrast media in the inner canthal region (~) and the superior tear str ip (~--). (D) The normal nasolacrimal drainage system of the contralateral eye is shown for comparison.

NUCLEAR DACRYOCYSTOGRAPHY 257

metr izamide is a theoretical contra indicat ion

that has not proven to be a problem.

CONCLUSIONS

We have found nuclear DCG to be a most useful procedure. It converts subjective pat ient complaints into an objective assessment of the

functional status of nasolacrimal drainage, and at the same time, provides graphic documenta- tion at a given point in time.

Nuclear DCG is simple to perform, involves little pat ient discomfort, and is relatively harm- less. It is readily performed by an experienced

technologist with minimal medical supervision. Although it provides a good functional assess- ment of nasolacrimal drainage, it has serious shortcomings in defining pathologic anatomy.

Contrast DCG is the procedure of choice for demonst ra t ing anatomical abnormal i t ies but often misses minor obstructions. The two tech- niques clearly complement each other.

ACKNOWLEDGMENT

The authors would like to acknowledge with gratitude the technical, secretarial, and artistic assistance of the following people: Jack L. Dixon, N.M.T., Pamela H. Jenkins, Betty J. Griffin, Martha Barrett Banick, and Thomas Crow.

REFERENCES

1. Rossomondo RM, Carlton WH, Trueblood JH, et al: A new method of evaluating lacrimal drainage. Arch Ophthal- tool 88:523-525, 1972

2. Carlton WH, Trueblood JH, Rossomondo RM: Clini- cal evaluation of microscintigraphy of the lacrimal drainage apparatus. J Nucl Med 14:89-92, 1973

3. Brizel HE, Sheils WC, Brown M: The effects of radio- therapy on the nasolacrimal system as evaluated by dacryo- scintigraphy. Radiology 116:373-381, 1975

4. E1 Gammal T, Brooks BS: Biplane magnification and subtraction Amipaque dacryocystography: A technical note. Radiology (in press)

5. Gullotta U, Denffer HV: Dacryocystography. An Atlas and Textbook. Stuttgart, Thieme-Stratton, 1980

6. Trueblood JH, Dunn JW: Personal communication, March 1981

7. Robertson JS, Brown ML, Colvard DM: Radiation absorbed dose to the lens in dacryoscintigraphy with 99mTcO4. Radiology 113:747-750, 1979

8. Denffer H, Dressier J: Radionukliddakryographie in Klinik und Forschung. Klin Mbl Augenheilk 169:66-72, 1976

9. Chaudhuri TK: A versatile way of instilling 99mTc- pertechnetate for nuclear dacryocystography. J Nucl Biol Med 20:84, 1976

10. Hurwitz J J, Maisey MN, Welham RAN: Quantita- tive lacrimal scintillography. I. Method and physiological application. Br J Ophthalmol 59:308-312, 1975

11. Hurwitz J J, Maisey MN, Welham RAN: Quantita- tive lacrimal scintillography. II. Lacrimal pathology. Br J Ophthalmol 59: 313-322, 1975

12. Trueblood JH, Rossomondo RM, Carlton WH, et al: Corneal contact times of ophthalmic vehicles. Evaluation by microscintigraphy. Arch Ophthalmol 93:127-130, 1975

13. Schaeffer JP: The Nose, Paranasal Sinuses, Nasola- crimal Passageways, and Olfactory Organ in Man. Philadel- phia, P. Blakiston's Son & Co, 1920