533
TECHNICAL NOTES
Vol. 122
Technical Noles
Subtraction Sialography 1 Walter H. Forman, M.D. 2 Subtraction sialography is described and demonstrated to be a simple yet helpful technique in evaluating the salivary glands. The improved visualization of the ductal system is demonstrated. INDEX TERM: Salivary glands, radiography, 2[64].1222 Radiology 122:533. February 1977
Radiographic evaluation of the salivary glands has included plain films, angiography (1), nuclear scanning (2), and sialography. The latter has been found to be the simplest, safest, and usually the most rewarding since its description in 1973 (3). Sialography has been used for the evaluation of intra- and extraglandular tumors, inflammatory disease, congenital defects, fistulas, cysts, and even as a therapeutic tool (3-5, 7). One problem common to all methods is overlap of the salivary glands and the bones of the face and neck on radiographs. We have used subtraction sialography to alleviate this situation. Liliequist used a subtraction technique with sialography, but with rapid film changers (6). Our method enables one to use any "overhead" or spot film device to obtain subtraction films. Following lateral, postero-anterior (PA) and oblique scout films of the salivary gland of interest, the duct is cannulated with polyethylene tubing. The patient is then put in the position for filming, usually the lateral projection. The patient is then instructed to remain very still and to use a prearranged hand signal to indicate pain in the gland of injection which will indicate filling of that gland. The contrast-free film is then exposed with a kVp near 70. The contrast material is then immediately injected and a second exposure obtained. The first film is used as the subtraction mask and the second as the contrast film. If the injection is made with an overhead device such as a head unit or "tabletop," the amount of contrast needed in the parotid gland will be 1.0-1.5 ml while in the submaxillary glands it will be between 0.5 and 1.0 ml. The patient's hand signal is a good indication that enough media has been injected and that the second exposure can be made. If the filming is done under fluoroscopic control as advocated by Yune and Klatte (7), adequate filling can be judged by fluoroscopy. Figure 1 is an example of a normal subtraction sialogram of the parotid gland in the lateral projection. Following this, overhead films are obtained in the PA and oblique projections. As previously stated, we usually obtain a subtraction film in the lateral projection, feeling this to be the most valuable film and the one in which there is more overlap of the ductal system and facial bones. Subtraction of the other projections can be performed in the same manner after drainage of the ductal system, facilitated by having the patient suck on a lemon. These are rarely needed. However, we have had a case in which a repeat lateral injection with a 5° tube shift enabled
Fig. 1. Subtraction sialogram of the parotid gland in the lateral projection demonstrating the excellent visualization of the ductal system.
us to obtain stereoscopic subtraction films and allowed differentiation of an intraglandular from an extraglandular mass. We have used this technique for two years and have shown it to be simple and effective; it adds no time and only one extra exposure to the routine sialogram. REFERENCES 1. Allen WE III, Kier EL, Rothman SLG: The maxillary artery in craniofacial pathology. Am J Roentgenol 121:124-138, May 1974 2. Sorsdahl OA, Williams CM, Bruno FP: Scintillation camera scanning of the salivary glands. Radiology 92: 1477-1480, Jun 1969 3. Blair GS: Hydrostatic sialography: an analysis of a technique. Oral Surg 36: 116-130, Jul 1973 4. Whinery JG: Treatment of recurrent parotitis in children (letter). J Oral Surg 32:488, Jul 1974 5. Meine FJ, Woloshin HJ: Radiologic diagnosis of salivary gland tumors. Radiol Clin N Am 8:475-485, Dec 1970 6. Liliequist B, We lander U: Siaglography: new application of the subtraction technique. Acta Radiol [Diag] 8:228-234, May 1969 7. Yune HY, Klatte EC: Current status of sialography. Am J Roentgenol 115:420-428, Jun 1972
1 From the Department of Radiology, USAF Medical Center, Keesler Air Force Base, Miss. 39534. Accepted for publication in April
1976. The opinions or assertions contained herein are the private views of the author and are not be construed as official or as reflecting the views of the Department of the Air Force or Defense at large. 2 Present address: Department of Radiology, Good Samaritan shan Hospital, West Palm Beach, Fla. 33402.
TECHNICAL NOTES
Vol. 122
Technical Noles
Subtraction Sialography 1 Walter H. Forman, M.D. 2 Subtraction sialography is described and demonstrated to be a simple yet helpful technique in evaluating the salivary glands. The improved visualization of the ductal system is demonstrated. INDEX TERM: Salivary glands, radiography, 2[64].1222 Radiology 122:533. February 1977
Radiographic evaluation of the salivary glands has included plain films, angiography (1), nuclear scanning (2), and sialography. The latter has been found to be the simplest, safest, and usually the most rewarding since its description in 1973 (3). Sialography has been used for the evaluation of intra- and extraglandular tumors, inflammatory disease, congenital defects, fistulas, cysts, and even as a therapeutic tool (3-5, 7). One problem common to all methods is overlap of the salivary glands and the bones of the face and neck on radiographs. We have used subtraction sialography to alleviate this situation. Liliequist used a subtraction technique with sialography, but with rapid film changers (6). Our method enables one to use any "overhead" or spot film device to obtain subtraction films. Following lateral, postero-anterior (PA) and oblique scout films of the salivary gland of interest, the duct is cannulated with polyethylene tubing. The patient is then put in the position for filming, usually the lateral projection. The patient is then instructed to remain very still and to use a prearranged hand signal to indicate pain in the gland of injection which will indicate filling of that gland. The contrast-free film is then exposed with a kVp near 70. The contrast material is then immediately injected and a second exposure obtained. The first film is used as the subtraction mask and the second as the contrast film. If the injection is made with an overhead device such as a head unit or "tabletop," the amount of contrast needed in the parotid gland will be 1.0-1.5 ml while in the submaxillary glands it will be between 0.5 and 1.0 ml. The patient's hand signal is a good indication that enough media has been injected and that the second exposure can be made. If the filming is done under fluoroscopic control as advocated by Yune and Klatte (7), adequate filling can be judged by fluoroscopy. Figure 1 is an example of a normal subtraction sialogram of the parotid gland in the lateral projection. Following this, overhead films are obtained in the PA and oblique projections. As previously stated, we usually obtain a subtraction film in the lateral projection, feeling this to be the most valuable film and the one in which there is more overlap of the ductal system and facial bones. Subtraction of the other projections can be performed in the same manner after drainage of the ductal system, facilitated by having the patient suck on a lemon. These are rarely needed. However, we have had a case in which a repeat lateral injection with a 5° tube shift enabled
Fig. 1. Subtraction sialogram of the parotid gland in the lateral projection demonstrating the excellent visualization of the ductal system.
us to obtain stereoscopic subtraction films and allowed differentiation of an intraglandular from an extraglandular mass. We have used this technique for two years and have shown it to be simple and effective; it adds no time and only one extra exposure to the routine sialogram. REFERENCES 1. Allen WE III, Kier EL, Rothman SLG: The maxillary artery in craniofacial pathology. Am J Roentgenol 121:124-138, May 1974 2. Sorsdahl OA, Williams CM, Bruno FP: Scintillation camera scanning of the salivary glands. Radiology 92: 1477-1480, Jun 1969 3. Blair GS: Hydrostatic sialography: an analysis of a technique. Oral Surg 36: 116-130, Jul 1973 4. Whinery JG: Treatment of recurrent parotitis in children (letter). J Oral Surg 32:488, Jul 1974 5. Meine FJ, Woloshin HJ: Radiologic diagnosis of salivary gland tumors. Radiol Clin N Am 8:475-485, Dec 1970 6. Liliequist B, We lander U: Siaglography: new application of the subtraction technique. Acta Radiol [Diag] 8:228-234, May 1969 7. Yune HY, Klatte EC: Current status of sialography. Am J Roentgenol 115:420-428, Jun 1972
1 From the Department of Radiology, USAF Medical Center, Keesler Air Force Base, Miss. 39534. Accepted for publication in April
1976. The opinions or assertions contained herein are the private views of the author and are not be construed as official or as reflecting the views of the Department of the Air Force or Defense at large. 2 Present address: Department of Radiology, Good Samaritan shan Hospital, West Palm Beach, Fla. 33402.
