9. Moon DH, Ryu JS, Lee MH, et al. Clinical value of DMSA planar and single-photon piglet using single-photon emission computerized dimercaptosuccinic emission eomputed tomography as an initial diagnostic tool in adult women with acid : a pathological correlation. J Ural 1993:150:759-762. recurrent acute . Nephron 1994:67:274-279. 13. Majd M. Rushton G. Chandra R, et al. Tcchnetium-99m-DMSA renal cortical 10. Rehm PK, Atkins FB, Tall JG. Ziessman HA. SPECT tcchnetium-99m-DMSA renal scintigraphy for the detection of acute pyelonephritis in piglets: comparison of planar scans: comparison of native versus reoriented axes [Abstract]. J NucíMetí1993:34: and SPECT imaging. Eur J NucíMed I994;21:343. 227P. 14. Williams ED. Renal single-photon emission computed tomography: should we do it? 11. Buscombe JR, Hilson AJW. Hall ML, et al. Looking for renal scars with technetium- Semin NucíMed 1992;22:112-121. 99m-DMSA SPECT: is it worth the effort? [Abstract]. J NucíMed 1993:34:138P. 15. Rossleigh MA. The interrenicular septum. A normal anatomical variant seen on 12. Giblin JG, O'Connor KP. Kildes RD. et al. The diagnosis of acute pyelonephritis in the DMSA SPECT. Clin NucíMed 1994:19:953-955.

Technetium-99m-DMSA Renal SPECT in Diagnosing and Monitoring Pediatrie Acute Pyelonephritis

Tzu-Chen Yen, Wei-Perng Chen, Shu-Lian Chang, Ren-Shyan Liu, Shin-Hwa Yeh and Ching-Yuang Lin Department and Division of and Department and Division of Pediatrics, Veterans General Hospital-Taipei and School of Medicine, National Yang-Ming University, Taipei, Taiwan

This study compares the sensitivity of 99mTc-dimercaptosuccinic by calyceal distortion of intravenous urography (IVU), repeated bouts of UTI, renal and even renal failure (7). It acid (DMSA) renal SPECT with planar scintigraphy, concluding the importance of 99nrTc-DMSA renal SPECT for the early diagnosis of has been reported that in children, APN will cause renal acute pyelonephritis (APN) in patients under 3 yr of age. Methods: scarring in 47% to 68% of patients through different modalities Twenty-seven children under 3 yr of age, with clinical and/or of imaging study (2) and recurrent episodes of APN will cause laboratory suspicion of APN, were investigated. All 99nTc-DMSA in one-third of patients progressive renal scarring, contracted, renal SPECT and planar images and voiding cystoureterogram distorted or small kidneys (3). In most children, diagnosing (VCUG) were obtained within 3 days of hospitalization. Results: In APN does not require complex and expensive procedures. From the first examination, renal cortical defects were detected in 23 our previous study, 99mTc-dimercaptosuccinic acid (DMSA) patients (42 kidneys) with SPECT and in 9 patients (11 kidneys) with renal SPECT scan has been found to be a useful diagnostic tool planar scintigraphy. One year after treatment, constant renal cortical in children (>3 yr old) with APN (4). However, in neonates lesions were observed in 11 patients (14 kidneys) with SPECT and 4 and infants with equivocal or negative urine cultures or with patients (4 kidneys) with planar scintigraphy. The high grades of vesicoureteral reflux (VUR) (grade >3) correlate better with APN recurrent cystitis and no evidence of pathologic vesicoureteral diagnosed by SPECT (34 kidneys) than by planar scintigraphy (8 reflux (VUR) proved by voiding cystoureterogram (VCUG), kidneys). Multiple renal cortical defects (number of lesions >4) were asserting or ruling out this diagnosis is mandatory for effective only seen in patients under 1.5 yr old and none of those with a management. In addition, following and monitoring the effect negative 99mTc-DMSA renal SPECT had a positive 99mTc-DMSA of treatment are also very important for determining the renal planar scintigraphy at any time. There is a significant difference prognosis of patients after APN. (p < 0.05) between the diagnostic ability of these two methods of Recent studies have compared the sensitivity and specificity examination. Conclusion: Our results suggest that "Tc-DMSA of various imaging modalities, including the WmTc-DMSA renal SPECT should be used, where possible, instead of planar renal scan, IVU, CT, ultrasonography (US) and MRI in detect DMSA in routine examination of children with clinical suspicion of ing renal lesions in children. SPECT renal imaging has proved APN, especially for those under 3 yr of age. to be superior to the other diagnostic modalities (4-10). Key Words: pediatrie acutepyelonephritis; SPECT; technetium- However, to the best of our knowledge, no report is known that 99m-dimercaptosuccinic acid uses the WmTc-DMSA renal SPECT technique to diagnose and J NucíMed 1996; 37:1349-1353 monitor APN in infants. In this research, we extend our previous studies using both WmTc-DMSA renal planar scintig Ur 'rinary tract infection (UTI), the admission diagnosis for raphy and SPECT to diagnose and follow up infants with a about 140 patients hospitalized per year in the Veterans General clinical suspicion of APN (4) and compare the results with the Hospital-Taipei, is most often due to Escherichia coli infection VCUG. of the renal parenchyma and collecting system. Although certain characteristics may help to differentiate acute pyelone METHODS phritis (APN) from cystitis, their clinical presentations are often similar. Sometimes it is difficult to distinguish between them. Patients The diagnosis of APN is very important for pediatrie patients, This study was performed between August I, 1992 and August especially for neonates and infants, because improper or de 30, 1994. Three hundred and nine patients were referred to by Pediatrie Ncphrologists of the Veterans General Hospital-Taipei. layed treatment of APN is often associated with the develop APN was defined as being present if they had all of the following: ment of renal scarring and/or chronic pyelonephritis, evidenced there was fever (>38.5°C), pyruia (WBC counts/HPF >10), a positive urinary culture and/or a positive blood culture. Twenty- Received June 12, 1995; revision accepted Dec. 13, 1995. For correspondence or reprints contact: Dr. Tzu-Chen Yen. Department of Nuclear seven of them were under 3 yr of age (from 1 wk old upward) and Medicine, Veterans General Hospital-Taipei, Taipei, Taiwan. clinically and/or laboratory diagnosed to have APN. The other 282

TECHNETIUM-99M-DMSARENALSPECT ANDAPN •Yen et al. 1349 patients, aged above 3 yr (from 3 to 12 yr), were diagnosed as TABLE 1 suffering from cystitis, acute or chronic pyelonephritis, high-grade Comparison of APN Detection Reliabilitybetween Planar VUR and small kidney(s). Technetium-99m-DMSA renal SPECT, Scintigraphy and SPECTin 27 Patientswith APN planar scintigraphy and VCUG were performed, with informed consent of the patients' parents, within 3 days after hospitalization Number of patients Number of patients with positive scan with negative scan for those with clinical impression of UTI including APN. After Method initial treatment for APN, all patients received prophylactic anti biotics until their second investigation 3 mo later. DMSA scans Planar scintigraphy 9(33) 18(67) were performed again 3 mo and 1 yr later. None had a recurrent SPECT 23 (85) 4(14) infection during that time. Only 3 of the 27 patients needed sedation by oral chlorohydrate (8.3 mg/kg), as the technicians were RESULTS experienced in handling and imaging pediatrie patients. The 27 infants (^3 yr old) ranged in age from 1 wk to 2.8 yr old (median, 0.7 yr) and the ratio of boys to girls was 12:15. A Technetium-99m-DMSA Renal Scan Method total of 23 patients (42 kidneys) with clinical impression of The 99rnTc-DMSA was prepared from a commercial kit and the APN were shown to have renal cortical lesions by WmTc- 99mTc-DMSA dose was based on the adult dose of 100 MBq and DMSA renal SPECT. Seventeen of the 23 positive children had corrected for the patient's age in years by the following formula: bilateral multiple (5:4) small lesions and all these 17 patients were under 1.5 yr of age. From the planar scintigraphic studies, (Age+ 1) X Adult dose only 9 children (11 kidneys) were changes of APN (Table 1). Of Dose = (Age + 7) ' the 27 children (54 kidneys), 38 kidneys had high-grade VUR. Thirty-four of the 38 high-grade VUR kidneys were shown to have cortical lesions by DMSA renal SPECT and in only 5 The minimum dose was 18 MBq (//). patients (8 kidneys) were cortical lesions detected by DMSA Imaging was done 3 hr after injection of the """Tc-DMSA. All renal planar scintigraphy (Table 2). During two follow-up studies were performed on digital with an inter examinations, 3 mo and 1 yr later, changes were recognized in faced computer. Planar images were acquired first, in the posterior the DMSA renal SPECT studies. Twelve children (20 kidneys) projection with a total of 300,000 counts per image using a became normal and 11 patients (22 kidneys) had persistent renal low-energy, high-resolution collimator. SPECT images were ob cortical defects (Fig. 1, 2). Nine patients (11 kidneys) revealed tained immediately after planar imaging and using 60 projections at positive results by planar scintigraphy initially. On follow-up 360°with 20 sec per stop. Following the application of a Matz studies, 5 patients (7 kidneys) showed normal by planar prefilter, transverse images were reconstructed with backprojection scintigraphy, but 2 of them (2 kidneys) were detected to have and a ramp filter. Coronal and sagittal views with respect to the scar formation by SPECT. The other 4 children (4 kidneys) patient were reconstructed from transverse slices without any showed new scar formation by both planar scintigraphy and additional filtering. Any photopenic area seen in the DMSA scan SPECT. If we took the positive scan identified by DMSA renal was evaluated to exclude the possibility of a cystic lesion or dilated SPECT as a standard, the occurrence of renal scarring after tubules by US and this was reconfirmed in the follow-up exami treatment for APN was 48% as detected by SPECT, which is nations. These studies were reviewed by three nuclear physicians in higher than the 17% detected with planar scintigraphy (p < random order without knowledge of the diagnosis or lesion 0.05) (Table 3). location. The resulting diagnosis and degree of cortical dysfunction In children more than 3 yr of age, the follow-up examinations were confirmed by at least two of the three interpreters. In the were also performed 3 mo and 1 yr later for those with UTI. planar images, the criteria used were according to those of Majd et Changes were found in 11 patients (14 kidneys) with UTI by al. and Patel et al. (12,13), including kidney contour, localization DMSA renal SPECT. Changes in only 2 patients (2 kidneys) of parenchymal defects, degree of photopenia and shape of defects. were seen with DMSA renal planar images. Except for small or In the SPECT images, the criteria used were according to those of distorted kidneys, none of them had multiple lesions (5:4) Monsour et al. (14), which included the presence of cortical detected by both DMSA renal SPECT and planar images (Table flattening, localized defect (one or multiple) in one or both kidneys 4). The results of these studies were reviewed after 10 days by and shrunken kidney(s). The interobserver and intraobserver reli the same nuclear physicians and after US, to exclude the ability was 85.7% and 95.2%, respectively. possibility of lesions being dilated renal tubules or cysts.

VCUG TABLE 2 Correlationof APN Diagnosedby RenalScan and Grade of VUR VCUG was performed after bladder catheterization with a 4.5 FG feeding tube. Hypaque was installed into the bladder slowly Number of patients from a height of 100 cm above the tabletop. The bladder was (number of kidneys) imaged fluoroscopically intermittently during filling and the cath VUR grade [criteria of eter was removed with continuous fluoroscopic imaging during Takedaet al. (JO)] voiding. The presence of VUR was graded on a scale from 0 to 5 Renal scan 0-2 3-5 in accordance with the International Reflux Study (75). Patients with VUR grade ^3 vere recognized as a high-grade VUR, while Planar(+)Planar others were considered low-grade (grade 1 and 2) or negative. (-)SPECT (+)SPECT (-)43525(8)15(30)18(34)2(4) Statistical Analysis All statistical analyses were performed by ANOVA-square analysis for categorical variables and the test for the continuous n = 27 neonates and infants (54 kidneys). variable. The p < 0.05 level was regarded as statistically signifi (+) and (-) denote presence and absence, respectively, of APN deduced cant. from the scan.

1350 THEJOURNALOFNUCLEARMEDICINE•Vol. 37 •No. 8 •August 1996 TABLE 3 Subsequent Occurrence of Renal Scarring Detected by Planar Scintigraphy and SPECT in 27 Cured APN Infants Renal cortical defects'

Method Positive scan Negative scan

Planar scintigraphy 4 23 SPECT 11 16

'Detection time: 3 mo after treatment and free of APN symptoms.

its high incidence in these groups (23). The prevention of ESRD, after APN during infancy, depends on early diagnosis and rapid, effective treatment to eradicate bacteria and prevent destructive reperfusion damage and that associated with inflam matory response. In the absence of preventive therapy, early diagnosis and early effective antibacterial therapy for APN are vital for the prevention of renal scarring or chronic pyelone phritis (24). In the past, CT was thought to be the first study of choice for a hospitalized patient in whom renal infection was suspected (4). CT demonstrates renal enlargement, poor corticomedullary definition and patchy areas of decreased density. However, CT is not as sensitive as 99mTc-DMSA (25). In addition, there may be some important drawbacks in the use of the technique in very young patients since sedation is required, respiratory move ments are out of control and fat is usually less in infants than in adults (6). IVU is normal in 75% patients with confirmed APN FIGURE 1. Two days after initial diagnosis of APN, SPECT studies clearly demonstrate (A, arrowheads) multiple photopenic areas. (B) Three months (7). Higher radiation exposure is another drawback of CT and after adequate treatment, follow-up studies show almost complete resolution IVU for infants because of the proximity of the gonads and their of the lesions. increased radiosensitivity before puberty. US is the more convenient and the least invasive imaging technique for use in infants. However, US has demonstrated abnormalities in only DISCUSSION 50% of patients with proven APN in one recent report (5). MRI Definite diagnosis of APN, although not easy, is very was used to detect renal lesions in children by Takeda et al. important, especially for neonates and infants who, with renal (70). The results showed that the smallest defects detected by infections, are often severely ill and may have a life-threatening MRI and renal SPECT were 8 mm and 10 mm, respectively. yet curable disease. Kidneys of children appear to be more Both had similar positive rates (MRI 83% versus renal SPECT vulnerable to the damaging effects of infection occurring during 85%). However, MRI has the disadvantage of high cost, and the first 3 yr (76). In the same studies, they showed that all adult artifacts caused by respiration and other motion (10). For these subjects who had their first infection during infancy had reasons, DMSA is frequently more indicative of APN than the decreased renal function. One-third would finally have hyper clinical or laboratory examination, and also has been considered tension, and 10% would progress to end-stage renal disease as the gold standard investigation in evaluating renal cortical damage in infants and young children (26). Technetium-99m- (ESRD) (16,17). Improper or delayed treatment for APN may cause renal scarring and subsequent discovery of shrunken DMSA exhibits superior image characteristics, compared with kidney(s) or at least of cortical scars (18-21), which has been other radiopharmaceuticals, for the clinical assessment of kid associated with the later development of hypertension and ney morphology and also has been used to evaluate renal ESRD. Besides, during the acute phase of APN, sepsis is the most common complication of improperly treated or untreated TABLE 4 APN (22). Infants and the elderly who have APN should be Comparison of Lesion Numbers of APN Detected by Renal Scan hospitalized and treated as if sepsis is already presented due to in Infants and Children

(number of (number of patients/ number patients/number of kidneys)lesionof kidneys)lesion

numbers numbers MethodPlanar >47/7==3 s42/2<3

2/4 0 SPECTInfants 6/8 17/34Children 11/14 0

FIGURE 2. In planar studies, most negative findings are shown both (A) 2 "Infants aged 0-3 yr; children aged 3-14 yr. days after initial diagnosis of APN and (B) 3 mo after adequate treatment.

TECHNETIUM-99M-DMSARI;NALSPECT ANDAPN •Yen et al. 1351 function (27). Although several factors such as the chemical We therefore recommend the use of 99mTc-DMSA renal SPECT formulation (28), binding to plasma macromolecules (29), instead of planar scintigraphy as the preferable study to help biochemical and physiological alterations and the presence of pediatrie urologists and nephrologists with early diagnosis, unlabeled DMSA (30) can alter the uptake, biodistribution and follow-up and monitoring of the effects of treatment in infants excretion of DMSA. Most of these flaws can be overcome by with APN. strictly following the manufacture's instructions during prepa ration of the kit. DMSA can reflect differential perfusion and function and acutely show changes in these functions, whereas ACKNOWLEDGMENT This work was supported by grant NSC 83-0412-B-075-076 CT, IVU and US can demonstrate the anatomical damage which is the end result of functional disturbance and may be shown on from the National Science Council, Taiwan. follow-up not in acute studies. SPECT is more readily available now. In the past, the REFERENCES diagnostic criteria of renal cortical dysfunction for planar 1. Jakobsson B, Nolstedl L, Svensson L. et al. Technetium-99m-DMSA scan in the scintigraphy included abnormal contours, localized parenchy diagnosis of acute pyelonephritis: relation to clinical and radiological finding. Pet/ialr Nephrol 1992;6:328-334. ma! defect(s), degree of photopenia and shape of defect(s) (#). 2. Berg UB. Long-term follow-up of renal morphology and function in children with Although planar scintigraphy has a spatial resolution higher recurrent pyelonephritis. 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Medical versus surgical treatment of primary vesicoureteric reflux: a prospective international reflux study in children. SPECT in neonates and infants is higher than that (24%) in the J Urol 1981:125:277-283. study in children from Jakobsson et al. (33 ). The reason may be 16. Berg UB. Johansson SB. Age as a main determinant of renal functional damage in due in part, to the different method (planar or pinhole versus urinary tract infection. Arch Dis Child 1982:58:963-969. 17. Jacobsson SH. Eklof O. Eriksson CG, et al. Development of hypertension and uremia SPECT) and study subjects (children versus neonates and after pyelonephritis in childhood: 27-year follow up. Br Med J 1989:299:703-706. infants). If using high-grade VUR (>3) detected by VCUG (38 18. Winberg J, Anderson HJ. Bergstrom T. et al. Epidemiology of symptomatic urinary kidneys) as the standard, the correlations between high-grade tract infection in childhood. Acta Pathol Scand Suppl 1974:252:1-20. 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Urol Clin North found by others for children (34-36) implying reflux itself is a Am 1986:13:637-645. 24. Miller T, Phillips S. Pyelonephritis: the relationship between infection, renal scarring more important risk factor for APN in neonates and infants than and antimicrobial therapy. Kidney Int 1981:19:654-662. in older children. The low percentage may simply be due to the 25. Majd M, Shalaby-Rana E, Rushton HG, Chandra R. Diagnosis of experimental acute decreased detection rate of renal cortical defects found by using pyelonephritis in piglets: comparison of CT and ""'"Tc-DMSA scintigraphy. Radiologi 1994:193:136. planar scintigraphy rather than SPECT. 26. Rushton HG, Majd M. Dimercaptosuccinic acid renal scintigraphy for the evaluation of pyelonephritis and scarring: a review of experimental and clinical studies. J Urol 1992:148:1726-1732. 27. Maneval DC. D'Argenio DX. Wolf W. A kinetic model for """Tc-DMSA in the rat. CONCLUSION Eur J NucíMed 1990:16:29-34. 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1352 THEJOURNALOFNUCLEARMEDICINE•Vol. 37 •No. 8 •August 1996 31. Obling H. Claesson l, Ebel KD, et al. Renal scars and parenchymal thinning in children (DMSA) scan in the diagnosis of acute pyelonephritis in children: relation to clinical with vesicoureteral reflux: a 5-year report of the International Reflux Study in Children and radiological findings. Pediatr Nephrol 1992;6:328-334. (European branch). J Urol I992;148:1653-1666. 35. Rushton 11G, Majd M. Dimercaptosuccinic acid and renal scarring: a review of 32. Chao SM, Saw AH, Tan CL. Vesicoureteric reflux and renal scarring in children—a experimental and clinical studies. J Urol 1992;I48:I726-1732. local perspective. Annal Acad Med. Singapore 1991;20:335-339. 36. Verber IG, Stnidley MR, Meiler ST. Technetium-99m-dimercaptosuccinic acid 33. Jakobsson B, Berg U, Svensson L. Renal scarring after acute pyelonephritis. Arch Dis Child 1994;70:I11-I15. (DMSA) scan as first investigation of urinary tract infection. Arch Dis Child 34. Jakobsson B, Nolstedt L, Svensson L, et al. Technetium-99m-dimercaptosuccinic acid 1988;63:1320-1325.

SPECT of Anterior Cruciate Ligament Injury

Gary J.R. Cook, Paul J. Ryan, Susan E.M. Clarke and Ignac Fogelman Department of Nuclear Medicine, Guys Hospital, London; and Department of Nuclear Medicine, Medway Hospital, Kent, United Kingdom

offers an alternative or complimentary imaging modality which This retrospective analysis of SPECT bone scans of the knee was is easily accessible for the investigation of knee pain. undertaken to define typical bone scan appearances and to assess We present a retrospective analysis of SPECT bone scintig the sensitivity of this method. We looked at 14 patients, mostly with chronic knee pain, who had anterior cruciate ligament (ACL) tears raphy of the knee in 14 patients who had ACL tears diagnosed detected by MRI. Method: Of the 14 patients, 10 were referred for with MRI, together with arthroscopic correlation available in 10 bone scanning following injury and 4 complained of chronic knee cases, in an attempt to define the typical bone scan appearances pain without injury. Planar scans were performed 4 hr after the and the sensitivity of the method in this type of injury. injection of 750 MBq of 99nTc-MDP. Tomographie images were obtained by a 64 x 20-sec acquisition over 360°using a high- METHOD resolution collimator. MRI imaging included axial and sagittal, T1 Subjects weighted and coronal fast field echo (FFE) sequences. Ten patients Fourteen consecutive patients (9 men, 5 women; aged 25-54 yr; also had arthroscopy performed. Results: MRI scans showed 6 mean age 34 yr) who had ACL tears diagnosed by MRI were lone ACL tears and 8 combined with other ligamentous injuries. included with MRI being used as the standard of reference for ACL SPECT scans showed abnormalities in 10 patients in the region of ACL insertions but only 4 planar studies were abnormal. SPECT tears. All had bone scintigraphy of the knee with SPECT. Ten identified focal activity at the upper (n = 8) or lower (n = 2) insertion patients were referred following injury, usually from sports, be of the ACL. Six of 10 arthroscopies confirmed ACL tears, 2 com tween 3 wk and 18 mo after the injury. Four patients complained plete and 4 partial. Overall, agreement was found with MRI in 10 of of chronic unilateral knee pain for more than 1 yr without a specific 14 cases and in 8 of 10 with arthroscopy. Abnormalities were injury being recalled. Ten patients also had diagnostic arthroscopy identified in 10 of 11 regions of other ligament or bone injury performed. identified by MRI. Conclusion: SPECT bone scanning of the knee is In the 10 patients with knee injury, MRI was performed within superior to planar imaging in detecting ACL injury and is a sensitive a median of 2.5 mo (range 0 to 18 mo) of the bone scan. In the 2 technique. Focal activity may be seen at either end of ACL attach patients in whom the interval between bone scan and MRI was ment but more commonly at the upper femoral insertion. Knee greater than 4 mo, one had arthroscopy within 3 mo of the bone SPECT may be a valuable examination in suspected ACL injury, particularly if MRI is not available, is equivocal or where clinical signs scan and the other had MRI within 1 mo of arthroscopy. Both had are absent. continued but stable pain throughout this period with no new Key Words: anterior cruciate ligament; knee SPECT; technetium- injuries. 99m-MDP Of the four patients with chronic knee pain without injury, two had an interval of less than 4 mo between bone scan and MRI and J NucíMed 1996; 37:1353-1356 the remaining two had a gap of 16 and 18 mo with the MRI predating the bone scan in each case. One is still awaiting Ihere is considerable experience with SPECT bone scintigra- arthroscopy and the other had arthroscopy within 2 mo of the MRI. phy of the lumbar spine with improved sensitivity for the Two patients had arthroscopic meniscectomy performed after detection of pathology when compared to a planar study (1,2). the bone and MRI scans. Two patients have subsequently had ACL Imaging of the knee with this technique also appears promising prostheses inserted and the remainder have been treated conserva but previous studies have been largely confined to the diagnosis tively. of meniscal tears (3-5). Scan Interpretation Soft-tissue injuries to the knee are generally well demon Bone scans were interpreted by a nuclear medicine specialist strated by MRI. Results for anterior cruciate ligament (ACL) (I.F.) with extensive experience in knee bone SPECT. MRI scans injury vary widely, however, and both false-negatives and false-positives have been described (6-8). In addition, MRI is had been interpreted by an MRI specialist radiologist. Neither were aware of the others scan results or of clinical or arthroscopic not universally available. Therefore, SPECT bone scintigraphy findings. Imaging Protocols Received June 5, 1995; revision accepted Dec. 13, 1995. Bone Scintigraphy. Blood-pool images were taken in the poste For correspondence or reprints contact: Dr. G.J.R. Cook, Department of Nuclear rior projection 5 min after the injection of 750 MBq 99nTc-MDP. Medicine, Guys Hospital, London SE1 9RT UK.

SPECT OFTHEKNEE•Cook et al. 1353