urothelial carcinoma of the upper urinary tract ( renal pelvis and ureter ; uut - uc ) is an infrequent genitourinary malignancy accounting for 5  % of urothelial cancers and less than 10  % of renal tumours . analysis of epidemiological and survival patterns of uut - uc over the past 30  years in a review of a large , population - based database in the usa has shown that the incidence of uut - uc has slowly risen , and that increasing patient age , male gender , afro - american race , bilateral uut - uc and regional / distant disease are all associated with poorer survival . for the primary diagnosis and staging of uut - uc , radiographic imaging by intravenous and retrograde pyelography and ct scanning , ureteroscopic visualization and biopsy of the tumour , and urine cytology are usually performed . although f - fdg is the radiopharmaceutical most frequently used in pet , fdg is not a useful tracer for the detection of primary tumours of the urinary tract because of its renal excretion . therefore , the utility of fdg pet in the detection of urinary tract tumours is limited to distant metastases [ 3 , 4 ] . it has been reported that fdg pet / ct is superior to conventional evaluations in detecting occult metastases in patients with invasive bladder cancer [ 5 , 6 ] . however , another study has shown no advantage of fdg pet / ct over ct alone for lymph node staging in invasive bladder cancer . a number of studies have demonstrated that pet / ct with c - choline ( choline pet / ct ) is useful in the detection of lymph node metastases of prostate cancer [ 815 ] and also the detection of primary prostate cancer with certain limitations [ 1620 ] . however , to the best of our knowledge , there have been no studies on the efficacy of choline pet / ct in the initial diagnosis and local staging of uut - uc . the purpose of this pilot study was to prospectively evaluate the impact of choline pet / ct in localizing the primary tumour and staging of uut - uc . in this study , the effects of the choline pet / ct findings on the clinical management of uut - uc and the outcomes in patients with uut - uc were also evaluated . all procedures followed the clinical guidelines of our hospital and were approved by the institutional review board . a complete description of the study was given to all participating patients and a consent form was signed by the patients . we enrolled 16 consecutive patients with a clinical suspicion of uut - uc ( 9 men , 7 women ; age range 51    83  years , mean    sd 69    10.8  years ) who were referred to the department of urology of our hospital between march 2008 and january 2011 . all patients were examined using choline pet / ct 3    65  days ( mean 19.2  days ) before surgery . two patients were inoperable and one patient needed no surgery ; all remaining patients underwent laparoscopic nephroureterectomy together with partial cystectomy ( lnux ) . in the patients who were diagnosed with lymph node metastases , lymphadenectomy was performed . in addition , after choline pet / ct some of the patients received neoadjuvant chemotherapy with gemcitabine and cisplatin [ 22 , 23 ] and chemotherapy with methotrexate , vinblastine , doxorubicin and cisplatin , with gemcitabine and carboplatin , and with gemcitabine . pet and ct imaging was performed using a combined pet / ct system ( biograph sensation 16 ; siemens medical solutions , forchheim , germany , and hoffman estates , il ) . the system combines a full - ring pet scanner equipped with lutetium orthosilicate crystal detectors and a 16-slice high - resolution spiral ct scanner . all patients were examined after fasting for 6  h. choline pet / ct was performed 10 and 20  min after intravenous injection of 3.7  mbq / kg of c - choline . in the pet / ct scanner , their arms were down and their hands were clasped on the abdomen throughout the scanning procedure rather than elevated above the head . first , a topogram was acquired to define the imaging range for both ct and pet . the range was typically chosen to extend from the scull base to the mid - thigh level . a single nonenhanced continuous spiral multislice ct scan was performed ( 120  kvp tube voltage , 100 mas effective tube current , 16    1.5-mm detector configuration , gantry rotation time 420  ms , 30-mm table feed per rotation ) . attenuation was measured during the first half of helical rotation , and the effective tube current was automatically modulated for the second half ( care dose ; siemens medical solutions , hoffman estates , il ) . data were acquired for 1  min per bed position following the ct scan . in all patients scanning the mean radiation doses used in this study were 1.1  msv in choline pet and 7.05  msv in ct . ct images with a matrix size of 512    512 and a slice thickness of 3  mm with a 1.5-mm increment were generated using filtered back - projection . pet images with a matrix size of 128    128 were reconstructed using a 3-d numerical reconstruction algorithm ( e.soft ; siemens medical solutions ) . ct - derived attenuation maps were used for pet attenuation correction . for visual and quantitative analysis , images were displayed on a clinical image analysis workstation that allowed interactive exploration of ct , pet and fused pet / ct image data . the loci where choline uptake was visibly higher than the activity of adjacent areas were tentatively considered uptake - positive . for each uptake - positive locus the intensity of uptake was further analysed semiquantitatively . for this purpose the coronal slice that contained the maximum uptake was selected and the maximum standardized uptake value ( suvmax ) with regard to body weight was determined . in this study , it was demonstrated that , when suvmax was lower than 2.2 , the contour and extent of the uptake area were vague . the size of tumours ( long diameter    short diameter    height ) was measured on ct images . histopathological examinations were performed in 14 of the 16 study patients . in 13 patients specimens were obtained from tissue resected during lnux and in 1 patient from tissue obtained at autopsy . kaplan - meier analysis was used to compare the survival of the patients with uut - uc in relation to the presence and location of metastases . the analyses were performed with the log - rank test using spss v. 20 ( ibm , armonk , ny ) . the suvmax at 10 and 20  min after injection were compared using the paired t - test . all procedures followed the clinical guidelines of our hospital and were approved by the institutional review board . a complete description of the study was given to all participating patients and a consent form was signed by the patients . we enrolled 16 consecutive patients with a clinical suspicion of uut - uc ( 9 men , 7 women ; age range 51    83  years , mean    sd 69    10.8  years ) who were referred to the department of urology of our hospital between march 2008 and january 2011 . all patients were examined using choline pet / ct 3    65  days ( mean 19.2  days ) before surgery . two patients were inoperable and one patient needed no surgery ; all remaining patients underwent laparoscopic nephroureterectomy together with partial cystectomy ( lnux ) . in the patients who were diagnosed with lymph node metastases , lymphadenectomy was performed . in addition , after choline pet / ct some of the patients received neoadjuvant chemotherapy with gemcitabine and cisplatin [ 22 , 23 ] and chemotherapy with methotrexate , vinblastine , doxorubicin and cisplatin , with gemcitabine and carboplatin , and with gemcitabine . pet and ct imaging was performed using a combined pet / ct system ( biograph sensation 16 ; siemens medical solutions , forchheim , germany , and hoffman estates , il ) . the system combines a full - ring pet scanner equipped with lutetium orthosilicate crystal detectors and a 16-slice high - resolution spiral ct scanner . all patients were examined after fasting for 6  h. choline pet / ct was performed 10 and 20  min after intravenous injection of 3.7  mbq / kg of c - choline . in the pet / ct scanner , their arms were down and their hands were clasped on the abdomen throughout the scanning procedure rather than elevated above the head . first , a topogram was acquired to define the imaging range for both ct and pet . the range was typically chosen to extend from the scull base to the mid - thigh level . a single nonenhanced continuous spiral multislice ct scan was performed ( 120  kvp tube voltage , 100 mas effective tube current , 16    1.5-mm detector configuration , gantry rotation time 420  ms , 30-mm table feed per rotation ) . attenuation was measured during the first half of helical rotation , and the effective tube current was automatically modulated for the second half ( care dose ; siemens medical solutions , hoffman estates , il ) . data were acquired for 1  min per bed position following the ct scan . in all patients scanning the mean radiation doses used in this study were 1.1  msv in choline pet and 7.05  msv in ct . ct images with a matrix size of 512    512 and a slice thickness of 3  mm with a 1.5-mm increment were generated using filtered back - projection . pet images with a matrix size of 128    128 were reconstructed using a 3-d numerical reconstruction algorithm ( e.soft ; siemens medical solutions ) . for visual and quantitative analysis , images were displayed on a clinical image analysis workstation that allowed interactive exploration of ct , pet and fused pet / ct image data . the loci where choline uptake was visibly higher than the activity of adjacent areas were tentatively considered uptake - positive . for each uptake - positive locus the intensity of uptake was further analysed semiquantitatively . for this purpose the coronal slice that contained the maximum uptake was selected and the maximum standardized uptake value ( suvmax ) with regard to body weight was determined . in this study , it was demonstrated that , when suvmax was lower than 2.2 , the contour and extent of the uptake area were vague . the size of tumours ( long diameter    short diameter    height ) was measured on ct images . histopathological examinations were performed in 14 of the 16 study patients . in 13 patients specimens were obtained from tissue resected during lnux and in 1 patient from tissue obtained at autopsy . kaplan - meier analysis was used to compare the survival of the patients with uut - uc in relation to the presence and location of metastases . the analyses were performed with the log - rank test using spss v. 20 ( ibm , armonk , ny ) . the suvmax at 10 and 20  min after injection were compared using the paired t - test . the profiles of the 16 study patients , and the choline uptake determined as suvmax and the sizes estimated on ct images of the primary tumours are shown in table  1 . the clinical findings , treatment , and outcomes in the patients , and histopathological findings of the primary tumours are shown in table  2.table 1patient profiles and c - choline uptake and sizes of primary tumours estimated on pet / ct imagespatient no.age ( years)sexprimary tumoursidelocation 
 c - choline uptake ( suvmax)size ( mm ) 
 10  min20  min161mrightrenal pelvis2.483.7929    25    20267frightrenal pelvis5.524.3637    26    20350fleftureter2.802.9410    9    12473frightureter  < 2.2  < 2.2indeterminable 
 556mrightureter  < 2.2  < 2.215    15    15 
 681mrightrenal pelvis3.833.4319    25    12783mrightrenal pelvis2.742.8310    9    12881mleftrenal pelvis2.313.228    8    15969fleftrenal pelvis4.063.9723    20    121075mrightureter2.492.1810    9    81164frightureter6.096.2811    10    81253mrightrenal pelvis7.858.0846    45    401356frightureter3.252.6412    11    121481mleftureter3.973.7910    10    101567frightureter  < 2.2  < 2.214    14    501681mrightureter6.593.8025    17    25 
 long diameter    short diameter    height 
 nonmalignancytable 2clinical findings , treatment , and outcomes in patients and histopathological findings of tumourspatient no.tnm classification 
 treatmentinterval from pet / ct to lnux ( days)histopathological findingsoutcomedays after lnux 
 1iii ( t3n0m0)lnux33uc , g2  >  g3 pt3 , ly0 , v0 , n0ned1,5302iv ( t4n2m1)inoperable  uc , g3 , pt4died from cancer25 ( after pet / ct ) 3i ( t1n0m0)lnux45malignant lymphomaned1,5604lnux10no malignancyned6995ned60a ( t1an0m0)lnux14uc , g1 , pta , ly0 , n0 , v0died from cancer7257i ( t1n0m0)lnux7uc , g2 , pt1 , ly0 , n0 , v0ned1,4518i ( t1n0m0)lnux13uc , g2 , pt1 , ly0 , n0 , v0ned1,4269ii ( t2n0m0)lnux42uc , g2  =  g3 , pt2 , ly0 , v0 , n0ned1,40210i ( t1n0m0)lnux45uc , g2  >  g3 , pt1 , ly0 , v0 , n0ned1,39911iv ( t2n1m0)nac  +  lnux  +  mvac4uc , g2 - 3 , pt2 , ly+ , v+ , n+ned1,41412iv ( t4n0m1)lnux  +  mvac65uc  >  scc , g3 , pt4died from cancer18013lnux3igg4-related diseasened74314iv ( t3n1m0)lnux  +  ( g  +  cbdca)3uc , g3 , pt3 , inf , ew0 , ly0 , n0died from cancer60015 
 iv ( t4n0m0)lnux  +  nac61uc , g3 , pt4 , inf , ly2 , v1,n0alive with cancer59216iv ( t3n2m1)inoperable , galive with cancer510 ( after pet / ct ) 
 lnux laparoscopic nephroureterectomy and partial cystectomy ; nac neoadjuvant chemotherapy with gemcitabine and cisplatin ( two  cycles ) before or after lnux ; ned no evidence of disease chemotherapy : mvac methotrexate , vinblastine , doxorubicin , and cisplatin ( three  cycles ) after lnux ; g  +  cboca gemcitabine and carboplatin ( three  cycles ) after lnux ; g gemcitabine ( three  cycles ) 
 according to sobin et al . 
 interval ( days ) between lnux and 14 july or 10 september 2012 . if patient died , interval between lnux and death . in patients who underwent no lnux , interval between pet / ct and 14 july or 10 september 2012 or deathmetastases in the sacral lymph nodes and 4th lumber spine were found 380 days after lnux 
 metastases in the sacral lymph nodes and 4th lumber spine were found 380 days after lnux patient profiles and c - choline uptake and sizes of primary tumours estimated on pet / ct images 
 long diameter    short diameter    height clinical findings , treatment , and outcomes in patients and histopathological findings of tumours 
 lnux laparoscopic nephroureterectomy and partial cystectomy ; nac neoadjuvant chemotherapy with gemcitabine and cisplatin ( two  cycles ) before or after lnux ; ned no evidence of disease   chemotherapy : mvac methotrexate , vinblastine , doxorubicin , and cisplatin ( three  cycles ) after lnux ; g  +  cboca gemcitabine and carboplatin ( three  cycles ) after lnux ; g gemcitabine ( three  cycles ) 
 according to sobin et al .  
 interval ( days ) between lnux and 14 july or 10 september 2012 . if patient died , interval between lnux and death . in patients who underwent no lnux , interval between pet / ct and 14 july or 10 september 2012 or deathmetastases in the sacral lymph nodes and 4th lumber spine were found 380 days after lnux 
 metastases in the sacral lymph nodes and 4th lumber spine were found 380 days after lnux of the 16 study patients , 13 were choline uptake - positive and the other 3 were uptake - negative in the urothelial lesions ( table  1 ) . in the three choline uptake - negative patients , the suvmax values were < 2.2 at both 10 and 20  min . except for two inoperable patients and one patient who needed no surgery , all patients underwent lnux . the specimens obtained by lnux or autopsy ( patient 2 ) were examined histopathologically , which confirmed that of the 13 choline uptake - positive patients , 11 patients ( patients 1 , 2 , 6    12 , 14 , and 16 ) had uut - uc , 1 ( patient 3 ) had malignant lymphoma , and 1 ( patient 13 ) had igg4-related disease ( table  2 ) . of the three uptake - negative patients , two ( patients 4 and 5 ) had no malignancies and 1 ( patient 15 ) had uut - uc ( table  2 ) . of the 2 patients with no malignancies , one ( patient 4 ) underwent lnux , and the lesion . the other patient ( patient 5 ) did not undergo lnux , but no malignancy was diagnosed based on his local and clinical findings . the uptake - negative patient with uut - uc ( patient 15 ) underwent lnux and the lesion was confirmed histopathologically to be uut - uc . of the 12 patients with uut - uc , 7 had renal pelvis carcinoma and 5 had ureteral carcinoma ( table  1 ) . in 6 of the 11 choline uptake - positive patients with uut - uc , the suvmax at 10  min was higher than at 20  min , and in 5 of these patients the suvmax at 20  min was higher than at 10  min . there was no statistically significant difference between the suvmax values of the urothelial lesions at 10  min and those at 20  min . the other 12 patients with uut - uc showed choline suvmax ranging from 2.48 to 7.85 ( mean    sd 4.15    1.73 ) at 10  min and from 2.83 to 8.08 ( 3.95    1.54 ) at 20  min , and a patient with malignant lymphoma in the left ureter ( patient 3 ) also showed choline uptake ( suvmax 2.80 at 10  min and 2.94 at 20  min ; tables  1 and 2 ) . there was incidentally a patient with igg4-related disease [ 25 , 26 ] who had a tumorous lesion in the right ureter ( patient 13 ) , and the lesion showed weak but definite choline uptake ( suvmax 3.25 at 10  min and 2.64 at 20  min ; tables  1 and 2 ) . the sensitivity of choline pet / ct in the detection of uut - uc was 92  % ( 11 of 12 patients ) . the nonmalignant tumorous ureteral lesion associated with igg4-related disease with positive uptake was considered false - positive as judged only on the basis of malignancy or nonmalignancy , whereas the other two nonmalignant ureteral lesions in patients 4 and 5 were uptake - negative . in 5 of the 12 patients with uut - uc ( patients 2 , 11 , 12 , 14 and 16 ) choline pet / ct also showed definite choline uptake in the sites corresponding to metastases , patients 11 and 14 had metastases only in the regional lymph nodes , and patients 2 , 12 and 16 also had distant metastases ( table  3 ) . these metastatic lesions were detected first by choline pet / ct performed in this study . choline uptake in the metastatic lesions was determined as suvmax and the size of the lesions was estimated on ct images ( table  3 ) . the suvmax values in the metastatic lesions were as high as in the primary tumours , ranging from 2.55 to 10.39 ( 5.75    1.85 ) at 10  min and from 2.28 to 11.80 ( 5.45    2.10 ) at 20  min .   in 10 of 15 choline uptake - positive metastatic lesions , the suvmax values at 10  min were higher than those at 20  min , in 4 the suvmax values at 20  min were higher than those at 10  min , and in 1 the suvmax values at 10 and 20  min were equal . the suvmax values at 10  min were significantly higher than those at 20  min ( p  <  0.05 ) . the size of the largest metastatic tumours ( 41    33    40  mm , left aortic lymph nodes in patient 16 ) approximated that of the primary tumour ( 46    45    40  mm , right renal pelvis in patient 12 ) . in one inoperable patient ( patient 2 ) , metastases were found in the skull , sixth thoracic spine , pelvis , left lung , and the right lower paratracheal and subaortic lymph nodes ; in another inoperable patient ( patient 16 ) , metastases were found in the left supraclavicular lymph nodes and the left anterior mediastinal lymph nodes as well as in the regional lymph nodes including the left aortic and common iliac lymph nodes ( table  3 ) . the metastatic tumours in the regional and distant lymph nodes were surgically resected ( patients 11 , 12 and 14 ) except in two inoperable patients ( patients 2 and 16 ) . table 3properties of metastatic lesionspatient no.locationsuvmaxsize ( mm ) 
 10  min20  min2right lower paratracheal ln5.094.5728    21    14subaortic ln5.394.4117    12    10thoracic spine ( vi)5.104.7117    15    12right iliac bone9.297.6035    33    20left lung2.552.2821    17    16skull5.074.4016    13    1611right internal iliac ln4.925.2211    10    912right renal hilar ln4.683.5721    10    12thoracic spine ( vi)6.456.0119    16    14thoracic spine ( xii)7.367.5536    30    26 right iliac bone10.3911.8028    25    1614left sacral ln4.735.1510    10    1016left aortic ln5.075.4641    33    40left common iliac ln5.855.8530    17    35left supraclavicular ln5.914.7320    10    10left anterior mediastinal ln4.163.8210    10    10 
 ln lymph node 
 long diameter    short diameter    height   properties of metastatic lesions 
 long diameter    short diameter    height   the outcome in all 16 study patients was checked on 14 july or 10 september 2012 ( 592 the outcomes in patients with distant metastases , with metastases only in the regional lymph nodes , and without metastases are compared in table  4 and fig . 1 . an inoperable patient ( patient 2 ) died from cancer 25  days after choline pet / ct and another inoperable patient ( patient 16 ) was alive with cancer 510  days after choline pet / ct . of the other two patients with metastases only in the regional lymph nodes , one ( patient 14 ) died from cancer 600  days after lnux , and one ( patient 11 ) had no evidence of disease 1,414  days after lnux . of seven patients with uut - uc without metastases , five ( patients 1 , 7 , 8 , 9 and 10 ) had no evidence of disease 1,399 1,530  days after lnux , one ( patient 6 ) died from another cause 725  days after lnux , and one ( patient 15 ) was alive with cancer 592  days after lnux , although in this patient metastases in the sacral lymph nodes and fourth lumbar spine were found 380  days after surgery ( the footnote relating to patient 15 in table 2 ) . patients with malignant lymphoma ( patient 3 ) or with igg4-related disease ( patient 13 ) had no evidence of disease 1,560 and 743  days after lnux.table 4outcomes in patients with distant metastases , with metastases only in regional lymph nodes , and without metastasespatient groupno . of patientssurgical treatmentoutcomedied from canceralive with cancerno evidence of disease 
 with distant metastases2 ( patients 2 , 16)no surgery1 
 1 
 1 ( patient 12)lnux  + lymphadenectomy1 
 with metastases only in regional lymph nodes2 ( patients 11 , 14)lnux + lymphadenectomy1 
 1without metastases6 ( patients 1 , 7 , 8 , 9 , 10 , 15 ) 
 1 
 5 
 lnux laparoscopic nephroureterectomy and partial cystectomy 
 seven patients had no metastases , but one died from another cause and was excluded 
 died from cancer 25  days after pet / ct 
 died from cancer 180  days after lnux 
 died from cancer 600  days after lnux 
 judged 510  days after pet / ct 
 see the footnote relating to patient 15 in table  2 

 judged 743    1,530  days after lnuxfig . 1kaplan - meier survival curves showing survival in patients with distant metastases ( three patients ) , with metastases only in the regional lymph nodes ( two patients ) , and without metastases ( six patients ) . see the footnotes to tables  2 and 4 
  outcomes in patients with distant metastases , with metastases only in regional lymph nodes , and without metastases 
 lnux laparoscopic nephroureterectomy and partial cystectomy 
 seven patients had no metastases , but one died from another cause and was excluded 
 died from cancer 25  days after pet / ct 
 died from cancer 180  days after lnux 
 died from cancer 600  days after lnux 
 judged 510  days after pet / ct 
 see the footnote relating to patient 15 in table  2 
 
 judged 743    1,530  days after lnux kaplan - meier survival curves showing survival in patients with distant metastases ( three patients ) , with metastases only in the regional lymph nodes ( two patients ) , and without metastases ( six patients ) . see the footnotes to tables  2 and 4 
  pet / ct images of the primary and metastatic tumours and the photographs  of the primary tumours after resection in patients 1 , 12 and 11 are shown in figs .  2 , 3 and 4.fig . a , b choline pet / ct images of the primary tumour at 10  min ( a ) and 20  min ( b ) after injection . choline uptake at 10  min is positive but weak ( suvmax 2.48 ) compared with that at 20  min ( suvmax 3.79 ) . a choline pet / ct images of the primary tumour at 10  min after injection ( suvmax 7.85 ) . c , d choline pet / ct images of the metastatic lesions at the 12th thoracic spine ( suvmax 7.36 , c ) and the right iliac bone ( suvmax 10.39 , d ) at 10  min after injection . e maximum intensity projection image . the metastatic lesions in the sixth thoracic spine and the right iliac bone are seen ( arrows)fig . a choline pet / ct images of the primary tumour at 10  min after injection ( suvmax 6.09 ) . c choline pet / ct images of the metastatic lesions at the right internal iliac lymph nodes at 10  min after injection ( suvmax 4.92 ) . a catheter is inserted into the right ureter ( a , d ) urothelial carcinoma of the left renal pelvis in patient 1 . a , b choline pet / ct images of the primary tumour at 10  min ( a ) and 20  min ( b ) after injection . choline uptake at 10  min is positive but weak ( suvmax 2.48 ) compared with that at 20  min ( suvmax 3.79 ) . circles tumour sites urothelial carcinoma of the right renal pelvis in patient 12 . a choline pet / ct images of the primary tumour at 10  min after injection ( suvmax 7.85 ) . c , d choline pet / ct images of the metastatic lesions at the 12th thoracic spine ( suvmax 7.36 , c ) and the right iliac bone ( suvmax 10.39 , d ) at 10  min after injection . e maximum intensity projection image . the metastatic lesions in the sixth thoracic spine and the right iliac bone are seen ( arrows ) urothelial carcinoma of the right ureter in patient 11 . a choline pet / ct images of the primary tumour at 10  min after injection ( suvmax 6.09 ) . c choline pet / ct images of the metastatic lesions at the right internal iliac lymph nodes at 10  min after injection ( suvmax 4.92 ) . c - choline is a small molecule that after intravenous injection is very quickly integrated into the cell membrane as phosphatidylcholine . it is a marker of membrane metabolism , and is subject to very late urinary excretion , so that the renal pelvis and ureter are free of urinary radioactivity at the time of image acquisition . nevertheless , there have been no studies so far on the efficacy of choline pet / ct in the detection of the primary tumour and metastases of uut - uc ; this was the principal motive for performing this study . of the 16 study patients with suspicion of uut - uc examined in the present study , in 12 uut - uc was confirmed . of the other four , one had malignant lymphoma , one had igg4-related disease , and two had benign diseases . of the 12 patients with uut - tc , 11 ( 92  % ) were choline uptake - positive and the other 1 was false - negative on choline pet / ct . the patient with malignant lymphoma and the patient with igg4-related disease were uptake - positive , and the two patients with nonmalignant diseases were uptake - negative . malignant cells have elevated levels of choline and upregulation of choline kinase activity [ 2730 ] . studies have been conducted to evaluate the ability and usefulness of choline pet / ct in detecting cancer within the prostate and in differentiating cancer from normal tissue and/or benign disease [ 1619 ] . in summary , these studies indicate that the use of choline pet / ct for initial diagnosis and local staging of prostate cancer can not be recommended as a first - line screening method in men at high risk of prostate cancer . in contrast , there have been a number of studies demonstrating that choline pet / ct is useful in detecting and staging lymph node metastases of prostate cancer [ 815 ] . in another study evaluating the ability of choline pet to detect bladder cancer before cystectomy , normal bladder showed little uptake , and primary bladder cancer was visualized in 10 of 18 patients with residual invasive disease in the cystectomy specimen . of the 12 patients with uut - uc examined in the present study , choline pet / ct revealed distant metastases in three , metastases only in the regional lymph nodes in two , and no metastases in seven . both distant metastatic lesions and regional lymph node metastases showed definite choline uptake and similar suvmax to the values in the primary tumours of uut - uc . according to the diagnostic findings on choline pet / ct , one of three patients with distant metastases and two patients with metastases only in the regional lymph nodes underwent lnux and lymphadenectomy , and seven patients without metastases underwent lnux . as shown in table  4 and fig .  1 , the outcome in patients with uut - uc corresponded to the patient classification based on the presence or absence of metastases and locoregional or distant metastases . these results suggest that choline pet / ct is useful in staging as well as in the primary diagnosis of uut - uc . choline uptakes determined as suvmax at 10  min were significantly higher than those at 20  min in metastatic tumours of uut - uc ( p  <  0.05 ) , whereas these was no statistically significant difference between the suvmax values at 10  min and those at 20  min in the primary tumours of uut - uc . although the reason for the difference between the primary and metastatic tumours of uut - uc is not yet known , the finding suggests that choline uptake takes place earlier in metastatic tumours than in primary tumours of uut - uc . the results indicate that choline uptake should be determined at both 10 and 20  min after injection for the detection of the primary and metastatic tumours of uut - uc . because the number of patients assessed in this pilot study was rather small , confirmation of this conclusion must await further follow - up studies with greater numbers of patients . besides uut - uc , the tumours developed in the ureter of a patient with malignant lymphoma and a patient with igg4-related disease were choline uptake - positive . igg4-related disease , which is characterized by elevated serum igg4 concentrations and tumefaction or tissue infiltration with igg4-positive plasma cells , is an under - recognized condition about which knowledge is now growing rapidly [ 25 , 26 ] . the present study demonstrated that inflammatory pseudotumour developed in the ureter of a patient with igg4-related disease and the tumour showed definite choline uptake . to our knowledge there have been no prior reports of definite choline uptake in tumorous lesions associated with igg4-related disease . the results of the present study showed that choline pet / ct is useful in detecting the primary tumours and metastases of uut - uc and potentially in providing valuable prognostic information . besides uut - uc , the ureteral tumours associated with malignant lymphoma and igg4-related disease showed definite choline uptake . follow - up studies with greater numbers of patients are needed to make the conclusions more reliable . the results of the present study showed that choline pet / ct is useful in detecting the primary tumours and metastases of uut - uc and potentially in providing valuable prognostic information . besides uut - uc , the ureteral tumours associated with malignant lymphoma and igg4-related disease showed definite choline uptake . follow - up studies with greater numbers of patients are needed to make the conclusions more reliable .