TY - JOUR T1 - Decoding acute pyelonephritis: imaging signatures and patterns of renal involvement across modalities TT - Akut piyelonefritin çözümlenmesi: modaliteler arasında görüntüleme bulguları ve renal tutulum paternleri AU - Karaalioğlu, Banu AU - Sağlık, Pelin AU - Akçay, Ahmet PY - 2025 DA - October Y2 - 2025 DO - 10.38053/acmj.1767841 JF - Anatolian Current Medical Journal JO - Anatolian Curr Med J / ACMJ / acmj PB - MediHealth Academy Yayıncılık WT - DergiPark SN - 2718-0115 SP - 751 EP - 759 VL - 7 IS - 6 LA - en AB - Aims: Acute pyelonephritis (APN) and acute focal bacterial nephritis (AFBN) are severe forms of urinary tract infection with overlapping clinical features. Differentiating these entities and assessing disease extent by imaging are critical for guiding management and preventing complications. Each modality has unique strengths and limitations. This study aimed to evaluate imaging-based differences between APN and AFBN and to assess the diagnostic performance of commonly used modalities.Methods: This retrospective study included 87 adult patients with renal parenchymal infection evaluated between 2018 and 2024. Imaging modalities comprised computed tomography (CT, n=87; 20 non-contrast, 67 contrast-enhanced), magnetic resonance imaging (MRI, n=20), and ultrasound (USG, n=53). Imaging features were compared between APN and AFBN. The diagnostic performance of non-contrast CT (NCCT), USG, and MRI was assessed using contrast-enhanced CT (CECT) as the reference standard. Agreement between CECT and contrast-enhanced MRI (CE-MRI) was analyzed using Cramer’s V. Results: APN was diagnosed in 40 patients (46%) and AFBN in 47 (54%). Complication rates, causative microorganisms, and associated findings did not differ significantly between groups. CECT was the most reliable modality, whereas USG (sensitivity 26.4%) often failed to detect the infection, and NCCT frequently failed to delineate the extent of disease. CE-MRI showed excellent agreement with CECT (Cramer’s V=0.93, p KW - Acute pyelonephritis KW - acute focal bacterial nephritis KW - magnetic resonance imaging KW - diffusion-weighted imaging KW - contrast-enhanced CT N2 - Arka Plan: Akut piyelonefrit (APN) ve akut fokal bakteriyel nefrit (AFBN), üriner sistem enfeksiyonlarının ağır formlarıdır. Bu iki tablonun ayırt edilmesi ve hastalık yaygınlığının görüntüleme ile değerlendirilmesi, hasta yönetimi ve komplikasyonları önlemek açısından kritik öneme sahiptir. Her görüntüleme modalitesinin kendine özgü güçlü ve sınırlı yönleri bulunmaktadır. Bu çalışmanın amacı, APN ve AFBN arasındaki görüntüleme temelli farklılıkları ortaya koymak ve sık kullanılan modalitelerin tanısal performansını değerlendirmektir.Yöntem: Bu retrospektif çalışmaya 2018–2024 yılları arasında renal parankim enfeksiyonu tanısı almış 87 erişkin hasta dahil edildi. Hastaların BT (n = 87; 20 kontrastsız, 67 kontrastlı), MRG (n = 20) ve ultrasonografi (USG, n = 53) görüntülemeleri değerlendirildi. Görüntüleme bulguları APN ve AFBN olguları arasında karşılaştırıldı. Kontrastsız BT (NCCT), USG ve MRG’nin kontrastlı BT (CECT)’ye göre tanısal performansları değerlendirildi. CECT ile kontrastlı MRG (CE-MRI) arasındaki uyum Cramer’s V ile analiz edildi.Bulgular: APN 40 hastada (%46), AFBN ise 47 hastada (%54) saptandı. Komplikasyon oranları, etken mikroorganizmalar ve ilişkili bulgular gruplar arasında anlamlı fark göstermemesi nedeni ile radyolojik farklılıkların farklı enflamatuvar patogenezlerden kaynaklandığı düşünüldü. CECT ile karşılaştırıldığında USG (duyarlılık %26,4) sıklıkla enfeksiyonu saptayamadı; NCCT ise hastalık yaygınlığını ortaya koymakta yetersiz kaldı. CE-MRI, CECT ile mükemmel uyum göstermesine rağmen (Cramer’s V = 0,93; p < 0,001), ek tanısal katkısı görülmedi. DWI’nun enfeksiyon yayılımını tanımlamada daha duyarlı olduğu gözlemlendi; AFBN’de ek odakları, APN’de ise daha lokalize hastalığı ortaya koydu. CE-T1WI’de görülen tüm lezyonlar T2WI’de de saptandı ve DWI ile T2WI’nin birlikte kullanımı tanısal güvenirliliği sağladı.Sonuç: APN ve AFBN benzer klinik ve mikrobiyolojik özellikler gösterse de, radyolojik paternler farklı enflamatuvar patogenezlere işaret etmektedir. CECT referans standart görüntüleme olarak alındığında, USG ve NCCT’nin tanısal değeri sınırlı kalmış, MRG—özellikle DWI ile T2WI’nin birlikte kullanımı—yüksek duyarlılık göstermiştir ve özellikle çocuklar, hamile hastalar ve böbrek fonksiyonları bozulmuş bireylerde kontrastsız umut verici bir alternatif olabileceği düşünülmüştür. CR - Johnson JR, Russo TA. Acute pyelonephritis in adults. N Engl J Med. 2018;378(1):48-59. doi:10.1056/NEJMcp1702758 CR - Czaja CA, Scholes D, Hooton TM, Stamm WE. Population-based epidemiologic analysis of acute pyelonephritis. Clin Infect Dis. 2007; 45(3):273-280. doi:10.1086/519268 CR - Chen K-C, Hung S-W, Seow V-K, et al. The role of emergency ultrasound for evaluating acute pyelonephritis in the ED. Am J Emerg Med. 2011; 29(7):721-724. doi:10.1016/j.ajem.2010.01.047 CR - Colgan R, Williams M, Johnson JR. Diagnosis and treatment of acute pyelonephritis in women. Am Fam Physician. 2011;84(5):519-526. CR - Siriwardana SR, Piyabani C. Role of imaging in renal infections: a narrative review. Sri Lankan J Infec Dis. 2024;14(1). doi:10.4038/sljid.v14i1.8602 CR - Bitsori M, Raissaki M, Maraki S, Galanakis E. Acute focal bacterial nephritis, pyonephrosis and renal abscess in children. Pediatr Nephrol. 2015;30(11):1987-93. doi:10.1007/s00467-015-3141-3 CR - Fujita Y, Kuwashima S, Nomura K, Kano Y, Yoshihara S. Diagnosis and treatment for acute focal bacterial nephritis with renal abscess based on magnetic resonance imaging evaluation. Pediatr Infect Dis J. 2021;40(7): e278-e280. doi:10.1097/INF.0000000000003118 CR - Oka H, Nagamori T, Yamamoto S, et al. Non-invasive discrimination of acute focal bacterial nephritis with pyelonephritis. Pediatr Int. 2019; 61(8):777-780. doi:10.1111/ped.13910 CR - Campos-Franco J, Macia C, Huelga E, et al. Acute focal bacterial nephritis in a cohort of hospitalized adult patients with acute pyelonephritis. Assessment of risk factors and a predictive model. Eur J Intern Med. 2017;39:69-74. doi:10.1016/j.ejim.2016.12.002 CR - Jiao S, Yan Z, Zhang C, Li J, Zhu J. Clinical features of acute focal bacterial nephritis in adults. Sci Rep. 2022;12(1):7292. doi:10.1038/s41598-022-10809-5 CR - Kaneko Y, Isono H. A case of acute focal bacterial nephritis with negative pyuria and urine culture test results. Cureus. 2022;14(12):e32942. doi:10. 7759/cureus.32942 CR - Smith AD, Nikolaidis P, Khatri G, et al. ACR Appropriateness Criteria® acute pyelonephritis: 2022 update. J Am Coll Radiol. 2022;19(11S): S224-S239. doi:10.1016/j.jacr.2022.09.017 CR - Kranz J, Bartoletti R, Bruyère F, et al. European association of urology guidelines on urological infections: summary of the 2024 guidelines. Eur Urol. 2024;86(1):27-41. doi:10.1016/j.eururo.2024.03.035 CR - Patino A, Martinez-Salazar EL, Tran J, Sureshkumar A, Catanzano T. Review of imaging findings in urinary tract infections. Semin Ultrasound CT MR. 2020;41(1):99-105. doi:10.1053/j.sult.2019.09.004 CR - Sieger N, Kyriazis I, Schaudinn A, et al. Acute focal bacterial nephritis is associated with invasive diagnostic procedures-a cohort of 138 cases extracted through a systematic review. BMC Infect Dis. 2017;17(1):240. doi:10.1186/s12879-017-2336-6 CR - Belyayeva M, Leslie SW, Jeong JM. Acute pyelonephritis. StatPearls [Internet]. StatPearls Publishing; 2024. CR - Jansaker F, Li X, Vik I, Frimodt-Moller N, Knudsen JD, Sundquist K. The risk of pyelonephritis following uncomplicated cystitis: a nationwide primary healthcare study. Antibiotics (Basel). 2022;11(12):1695. doi:10. 3390/antibiotics11121695 CR - Guella A, Khan A, Jarrah D. Acute focal bacterial nephritis: two cases and review of the literature. Can J Kidney Health Dis. 2019;6: 2054358119884310. doi:10.1177/2054358119884310 CR - El-Ghar MA, Farg H, Sharaf DE, El-Diasty T. CT and MRI in urinary tract infections: a spectrum of different imaging findings. Medicina. 2021;57(1):32. doi:10.3390/medicina57010032 CR - Piccoli GB, Consiglio V, Colla L, et al. Antibiotic treatment for acute ‘uncomplicated’or ‘primary’pyelonephritis: a systematic,‘semantic revision’. Int J Antimicrobial Agents. 2006;28:49-63. doi:10.1016/j.ijantimicag.2006.05.017 CR - Yu J, Koolstra C, Smit V, Mitra B. Rate and yield of imaging for acute pyelonephritis in the emergency department: a retrospective cohort study. Emerg Med Australas. 2025;37(1):e14555. doi:10.1111/1742-6723. 14555 CR - Gauthier S, Tattevin P, Soulat L, et al. Pain intensity and imaging at the initial phase of acute pyelonephritis. Med Mal Infect. 2020;50(6):507-514. doi:10.1016/j.medmal.2019.07.013 CR - Yu J, Sri-Ganeshan M, Smit V, Mitra B. Ultrasound for acute pyelonephritis: a systematic review and meta-analysis. Intern Med J. 2024;54(7):1106-1118. doi:10.1111/imj.16347 CR - Nakata M, Wakugawa T, Uehara H, Kenzaka T. Comparison of diffusion-weighted whole-body magnetic resonance imaging and abdominal ultrasonography versus contrast-enhanced computed tomography in diagnosing acute focal bacterial nephritis: a retrospective cohort study. Quant Imaging Med Surg. 2025;15(4):3298-3307. doi:10.21037/qims-24-1861 CR - Hazarika S, Venkataramanan R, Das T, et al. Acute renal infection in adult, part 1: an overview of what the radiologist needs to know. J Gastrointestinal Abdominal Radiol. 2019;03(02):126-136. doi:10.1055/s- 0039-1695656 CR - Hosokawa T, Tanami Y, Sato Y, Oguma E. Comparison of imaging findings between acute focal bacterial nephritis (acute lobar nephronia) and acute pyelonephritis: a preliminary evaluation of the sufficiency of ultrasound for the diagnosis of acute focal bacterial nephritis. Emerg Radiol. 2020;27(4):405-412. doi:10.1007/s10140-020-01771-8 CR - Jang YR, Ahn SJ, Choi SJ, et al. Clinical and computed tomography factors associated with sepsis in women with clinically uncomplicated pyelonephritis. Abdom Radiol (NY). 2021;46(2):723-731. doi:10.1007/s00261-020-02711-3 CR - Vernuccio F, Patti D, Cannella R, Salvaggio G, Midiri M. CT imaging of acute and chronic pyelonephritis: a practical guide for emergency radiologists. Emerg Radiol. 2020;27(5):561-567. doi:10.1007/s10140-020-01788-z CR - Sriman R, Venkatesh K, Mathew C, Pankaj M, Shankar R. Validity of diffusion-weighted magnetic resonance imaging in the evaluation of acute pyelonephritis in comparison with contrast-enhanced computed tomography. Pol J Radiol. 2020;85:e137-e143. doi:10.5114/pjr.2020.93669 CR - Boccatonda A, Stupia R, Serra C. Ultrasound, contrast-enhanced ultrasound and pyelonephritis: a narrative review. World J Nephrol. 2024;13(3):98300. doi:10.5527/wjn.v13.i3.98300 CR - Bodagala V, Sanga Reddi B, Lakshmi AY, Kumar N, Kumar V. Diffusion weighted MR imaging in the diagnosis of acute pyelonephritis and its complications: a prospective observational study. J Dr NTR University of Health Sciences. 2019;8(3):170-174. doi:10.4103/jdrntruhs.Jdrntruhs_ 116_18 CR - Pinto DS, George A, Johny J, Hoisala RV. Role of MRI in the evaluation of acute pyelonephritis in a high-risk population with renal dysfunction: a prospective study. Emerg Radiol. 2023;30(3):285-295. doi:10.1007/s10140-023-02122-z CR - Morgillo M, Bernabei C, Bianchi M, et al. Treatment response assessment of acute pyelonephritis: a multi-reader DWI-based MRI approach. Curr Probl Diagn Radiol. 2025;54(2):197-205. doi:10.1067/j.cpradiol.2024.07.019 CR - Faletti R, Cassinis MC, Fonio P, et al. Diffusion-weighted imaging and apparent diffusion coefficient values versus contrast-enhanced MR imaging in the identification and characterisation of acute pyelonephritis. Eur Radiol. 2013;23(12):3501-3508. doi:10.1007/s00330-013-2951-6 CR - Takada T, Yano T, Fujiishi R, et al. Added value of non-contrast CT for the diagnosis of acute pyelonephritis in older patients with suspected infection with an unknown focus: a retrospective diagnostic study. BMJ Open. 2024;14(1):e076678. doi:10.1136/bmjopen-2023-076678 UR - https://doi.org/10.38053/acmj.1767841 L1 - https://dergipark.org.tr/tr/download/article-file/5166236 ER -