Z Amin

University College London, Londinium, England, United Kingdom

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Publications (46)229.94 Total impact

  • V T F Cheung · D Joshi · Z Amin · G J Webster ·

    Gut 05/2014; 63(10). DOI:10.1136/gutjnl-2014-306987 · 14.66 Impact Factor
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    ABSTRACT: OBJECTIVE:: To evaluate the experience of a tertiary hepatopancreaticobiliary (HPB) center in the diagnostic approach and management of patients with suspicion of cholangiocarcinoma (CCa), focusing on excluding patients with IgG4-associated cholangitis (IAC) from unnecessary major surgical interventions. METHODS:: Between January 2008 and September 2010, a total number of 152 patients with suspicion of CCa underwent evaluation through a HPB multidisciplinary team meeting. Patients without tissue diagnosis were managed surgically or medically on the basis of probable presence of IAC as underlying pathology. Serology, immunostaining, and imaging were reviewed and analyzed according to the HISORt (Histology, Imaging, Serology, Other organ involvement, Response to therapy) criteria for IAC. RESULTS:: Tissue diagnosis during the diagnostic workup was achieved in 104 patients (68%), whereas the remaining 48 were classified as "highly suspicious for CCa" (n = 35) or as "probable IAC" (n = 13). Among 16 "highly suspicious for CCa" patients who underwent surgery, pathology revealed 2 patients harboring IAC (n = 1) and a benign chronic inflammatory biliary stricture (n = 1), respectively. Among the 13 patients with primarily medical management as "probable IAC," final diagnosis was CCa (n = 3) and IAC (n = 9), while 1 patient had no proven diagnosis. The accuracy of serum IgG4 for diagnosis of IAC reached 60%. Sensitivity and specificity of immunostaining for IAC in biopsy specimens were 56% and 89%, respectively. Imaging features suggesting IAC yielded sensitivity, specificity, and accuracy of 75%, 89%, and 83%, respectively. Initial imaging was revised at the referral institute in 75% of IAC patients (P = 0.009), while an isolated stricture (P = 0.038), a biliary mass (P = 0.006), and normal pancreas on computed tomography (P = 0.01) were statistically significant parameters for distinguishing between CCa and IAC. The mean time for establishing a diagnosis of IAC was 12.4 months (range: 2.5-32 months) CONCLUSIONS:: Differential diagnosis between CCa and IAC mandates high index of suspicion and low threshold for referral in high volume institutes. The delayed establishment of diagnosis particularly for CCa needs to be balanced versus avoiding unnecessary surgery for IAC. Imaging features may be most helpful for optimal management.
    Annals of surgery 05/2012; 256(6). DOI:10.1097/SLA.0b013e3182533a0a · 8.33 Impact Factor
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    ABSTRACT: Distinction of immunoglobulin G4-associated cholangitis (IAC) from primary sclerosing cholangitis (PSC) or cholangiocarcinoma is challenging. We aimed to assess the performance characteristics of endoscopic retrograde cholangiography (ERC) for the diagnosis of IAC. Seventeen physicians from centers in the United States, Japan, and the United Kingdom, unaware of clinical data, reviewed 40 preselected ERCs of patients with IAC (n = 20), PSC (n = 10), and cholangiocarcinoma (n = 10). The performance characteristics of ERC for IAC diagnosis as well as the κ statistic for intraobserver and interobserver agreement were calculated. The overall specificity, sensitivity, and interobserver agreement for the diagnosis of IAC were 88%, 45%, and 0.18, respectively. Reviewer origin, specialty, or years of experience had no statistically significant effect on reporting success. The overall intraobserver agreement was fair (0.74). The operating characteristics of different ERC features for the diagnosis of IAC were poor. Despite high specificity of ERC for diagnosing IAC, sensitivity is poor, suggesting that many patients with IAC may be misdiagnosed with PSC or cholangiocarcinoma. Additional diagnostic strategies are likely to be vital in distinguishing these diseases.
    Clinical gastroenterology and hepatology: the official clinical practice journal of the American Gastroenterological Association 06/2011; 9(9):800-803.e2. DOI:10.1016/j.cgh.2011.05.019 · 7.90 Impact Factor
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    ABSTRACT: The application of endobiliary self-expandable metallic stents (SEMS) is considered the palliative treatment of choice in patients with biliary obstruction in the setting of inoperable malignancies. In the presence of SEMS, however, radical surgery is the only curative option when the resectability status is revised in case of malignancies or for overcoming complications arising from their application in benign conditions that masquerade as inoperable tumours. The aim of our study was to report our surgical experience with patients who underwent an operation due to revision of the initial palliative approach, whilst they had already been treated with biliary SEMS exceeding the hilar bifurcation. Three patients with hilar cholangiocarcinoma that was considered inoperable and one patient with IgG4 autoimmune cholangio-pancreatopathy mimicking pancreatic cancer underwent radical resections in the presence of biliary SEMS. After a detailed preoperative workup, two right trisectionectomies, one left extended hepatectomy and a radical extrahepatic biliary resection were performed. All cases demanded resection and reconstruction of the portal vein. R0 resection was achieved in all the malignant cases. Two patients required multiple biliodigestive anastomoses entailing three and seven bile ducts respectively. There was one perioperative death due to postoperative portal vein and hepatic artery thrombosis, whilst two patients developed grade III complications. At follow-up, one patient died at 13 months due to disease recurrence, whilst the remaining two are free of disease or symptoms at 21 and 12 months, respectively. Revising the initial palliative approach and operating in the setting of biliary metallic stents is extremely demanding and carries significant mortality and morbidity. Radical resection is the only option for offering cure in such complex cases, and this should only be attempted in advanced hepatopancreaticobiliary centres with active involvement in liver transplantation.
    Journal of Gastrointestinal Surgery 03/2011; 15(3):489-95. DOI:10.1007/s11605-010-1389-2 · 2.80 Impact Factor
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    ABSTRACT: Duodenal webs are a cause of intestinal atresia in infants and surgical repair is the established treatment of choice. However, the late-onset postoperative complications have not been adequately studied, especially in adults who have undergone surgical interventions as infants. This report describes the case of a 65-year-old female patient who presented with consecutive episodes of acute pancreatitis and a history of duodenal atresia repaired by a gastrojejunostomy in early infancy. Imaging studies revealed the presence of megaduodenum and suggested the possibility of impacted stones at the ampulla of Vater. An intact duodenal web at the level of papilla of Vater was revealed during surgery. Excision of the web, tapering of the duodenum and duodenojejunostomy was performed to relieve the obstructive cause of pancreatitis and to restore the intestinal continuity. At the 1-year follow-up, the patient is free of any symptoms, has no diet restrictions, and has increased her body weight as well.
    Surgery Today 03/2011; 41(3):426-9. DOI:10.1007/s00595-009-4261-9 · 1.53 Impact Factor
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    ABSTRACT: Characteristic pancreatic duct changes on endoscopic retrograde pancreatography (ERP) have been described in autoimmune pancreatitis (AIP). The performance characteristics of ERP to diagnose AIP were determined. The study was done in two phases. In phase I, 21 physicians from four centres in Asia, Europe and the USA, unaware of the clinical data or diagnoses, reviewed 40 preselected ERPs of patients with AIP (n=20), chronic pancreatitis (n=10) and pancreatic cancer (n=10). Physicians noted the presence or absence of key pancreatographic features and ranked the diagnostic possibilities. For phase II, a teaching module was created based on features found most useful in the diagnosis of AIP by the four best performing physicians in phase I. After a washout period of 3 months, all physicians reviewed the teaching module and reanalysed the same set of ERPs, unaware of their performance in phase I. In phase I the sensitivity, specificity and interobserver agreement of ERP alone to diagnose AIP were 44, 92 and 0.23, respectively. The four key features of AIP identified in phase I were (i) long (>1/3 the length of the pancreatic duct) stricture; (ii) lack of upstream dilatation from the stricture (<5 mm); (iii) multiple strictures; and (iv) side branches arising from a strictured segment. In phase II the sensitivity (71%) of ERP significantly improved (p<0.05) without a significant decline in specificity (83%) (p>0.05); the interobserver agreement was fair (0.40). The ability to diagnose AIP based on ERP features alone is limited but can be improved with knowledge of some key features.
    Gut 12/2010; 60(5):666-70. DOI:10.1136/gut.2010.207951 · 14.66 Impact Factor

  • Gastroenterology 05/2010; 138(5). DOI:10.1016/S0016-5085(10)61808-2 · 16.72 Impact Factor

  • Annual General Meeting of the British-Society-of-Gastroenterology; 04/2010

  • Annual General Meeting of the British-Society-of-Gastroenterology; 04/2010
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    ABSTRACT: Autoimmune pancreatitis (AIP) is a multisystem disorder that often has extrapancreatic manifestations such as immunoglobulin G4-associated cholangitis (IAC). Patients respond rapidly to steroids but can relapse after therapy. We assessed the clinical management of relapse in a group of patients with AIP/IAC. We performed a prospective study of patients diagnosed with AIP from 2004-2007 who received steroids. Treatment outcome was defined clinically, radiologically, and biochemically as response to steroids, remission after steroids, failure to wean steroids, and relapse. Steroids +/- azathioprine (AZA) were used to treat patients who failed, relapsed, or could not be weaned from steroids. Twenty-eight patients with AIP were studied; 23 (82%) had IAC. All patients responded within 6 weeks to prednisolone therapy. Twenty-three patients achieved remission after a median of 5 months of treatment (range, 1.5-17 months), whereas 5 patients (18%) could not be weaned because of a disease flare. Of the patients who achieved remission, 8 of 23 (35%) subsequently relapsed. Overall, 13 of 23 patients (57%) with AIP/IAC relapsed, compared with 0 of the 5 with isolated AIP (P = .04, Fisher exact test). Steroids were increased/restarted in all patients who relapsed; 10 also received AZA. Remission was achieved and maintained in 7 patients; they remain on AZA monotherapy at a median of 14 months (range, 1-27 months). Relapse or failure to wean steroids occurred in 46% of patients with AIP. Patients with IAC are at particularly high risk of relapse. AZA appears to be effective in patients with post-treatment relapse or who cannot be weaned from steroids. To view this article's video abstract, go to the AGA's YouTube Channel.
    Clinical gastroenterology and hepatology: the official clinical practice journal of the American Gastroenterological Association 05/2009; 7(10):1089-96. DOI:10.1016/j.cgh.2009.03.021 · 7.90 Impact Factor

  • Gastrointestinal Endoscopy 04/2009; 69(5). DOI:10.1016/j.gie.2009.03.140 · 5.37 Impact Factor
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    ABSTRACT: Most cases of autoimmune pancreatitis (AIP) have been reported from Japan. We present data on a UK series, including clinical and radiological features at presentation, and longitudinal response to immunosuppression. Over an 18-month period, all patients diagnosed in our center with AIP were studied. Endoscopic biliary stenting was performed as required, and patients were treated with prednisolone, with response assessed longitudinally. In cases of disease relapse following steroid reduction, azathioprine was instituted. Eleven patients met diagnostic criteria for AIP. Diffuse pancreatic enlargement was seen in eight patients (73%), and pancreatic duct strictures in all. Seven patients required biliary stents. Extrapancreatic involvement occurred in all, including intrahepatic stricturing and renal disease. Eight weeks after starting steroids, the median serum bilirubin level had fallen from 38 mumol/L to 11 mumol/L (P= 0.001), and ALT from 97 IU/L to 39 IU/L (P= 0.002). Stents were removed in all cases, with no recurrence of jaundice. Improvements in mass lesions and pancreaticobiliary stricturing occurred in all patients. During a median 18-month follow-up, six patients relapsed, four of whom responded to azathioprine. Two patients discontinued steroids and remained well. Extrapancreatic disease was an important feature of AIP in this UK series. Initial response to immunosuppressive therapy was excellent, but disease relapse was common. Optimal long-term management remains to be established.
    The American Journal of Gastroenterology 12/2007; 102(11):2417-25. DOI:10.1111/j.1572-0241.2007.01531.x · 10.76 Impact Factor

  • Clinical Imaging 05/2007; 31(3):221-221. DOI:10.1016/j.clinimag.2007.02.014 · 0.81 Impact Factor
  • Z Amin · B Theis · R.C.G. Russell · C House · M Novelli · W.R. Lees ·
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    ABSTRACT: To determine the sensitivity and complications of percutaneous biopsy of pancreatic masses, and whether typical computed tomography (CT) features of adenocarcinoma can reliably predict this diagnosis. A 5 year retrospective analysis of percutaneous core biopsies of pancreatic masses and their CT features was undertaken. Data were retrieved from surgical/pathology databases; medical records and CT reports and images. Three hundred and three patients underwent 372 biopsies; 56 of 87 patients had repeat biopsies. Malignancy was diagnosed in 276 patients, with ductal adenocarcinoma in 259 (85%). Final sensitivity of percutaneous biopsy for diagnosing pancreatic neoplasms was 90%; for repeat biopsy it was 87%. Complications occurred in 17 (4.6%) patients, in three of whom the complications were major (1%): one abscess, one duodenal perforation, one large retroperitoneal bleed. CT features typical of ductal adenocarcinoma were: hypovascular pancreatic mass with bile and/or pancreatic duct dilatation. Atypical CT features were: isodense or hypervascular mass, calcification, non-dilated ducts, cystic change, and extensive lymphadenopathy. Defining typical CT features of adenocarcinoma as true-positives, CT had a sensitivity of 68%, specificity of 95%, positive predictive value (PPV) of 98%, and negative predictive value of 41% for diagnosing pancreatic adenocarcinoma. Final sensitivity of percutaneous biopsy for establishing the diagnosis was 90%. CT features typical of pancreatic adenocarcinoma had high specificity and PPV. On some occasions, especially in frail patients with co-morbidity, it might be reasonable to assume a diagnosis of pancreatic cancer if CT features are typical, and biopsy only if CT shows atypical features.
    Clinical Radiology 01/2007; 61(12):996-1002. DOI:10.1016/j.crad.2006.07.005 · 1.76 Impact Factor
  • YM Miao · D-M Koh · Z Amin · J C Healy · R J S Chinn · R Zeegen · D Westaby ·
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    ABSTRACT: Determining bowel disease activity in Crohn's patients can be difficult on clinical and laboratory assessment. Endoscopy is invasive and barium studies use ionising radiation. The aim of this study was to compare ultrasound and magnetic resonance imaging (MRI) in detecting Crohn's disease activity in the small or large bowel. Thirty patients, previously diagnosed with Crohn's disease, had bowel ultrasound and MR imaging, and were deemed active or inactive on each test. The 'gold standard' was based on clinical assessment and one or more of the following: endoscopy, barium studies or surgery. For determining Crohn's disease activity, the sensitivities and specificities of bowel ultrasound and MRI were 87 percent and 100 percent, and 87 percent and 71 percent, respectively. Significant parameters that defined disease activity were bowel wall thickening on ultrasound and MRI, and contrast enhancement of the bowel wall and mesenteric vascularity/stranding on MRI. Ultrasound and MRI were both sensitive for determining Crohn's disease activity in the bowel, but MRI with gadolinium enhancement was less specific.
    Clinical Radiology 11/2002; 57(10):913-8. DOI:10.1053/crad.2002.1059 · 1.76 Impact Factor
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    ABSTRACT: The purpose of this study was to evaluate the sensitivity and specificity of MR imaging in assessing the activity of Crohn's disease. Thirty symptomatic patients with Crohn's disease but uncertain disease activity were prospectively examined using MR imaging. Twenty-nine patients were scored using the Crohn's disease activity index. Six hundred milliliters of water orally and 1 mg of glucagon intramuscularly were given before imaging. Breath-hold images were obtained using T2-weighted turbo spin-echo, T1-weighted fast low-angle shot, and fat-suppressed gadolinium-enhanced T1-weighted fast low-angle shot sequences. Images were assessed by two radiologists who were unaware of the patient's symptoms, clinical scoring, and other imaging tests, and who reached a consensus about the imaging findings (bowel wall thickening, bowel wall enhancement, and perienteric changes) and determined the absence or presence of active disease in each patient. MR imaging findings were correlated with endoscopy and surgery. Twenty-three patients had active disease and seven patients had inactive disease. One hundred twenty-four of a total of 168 bowel segments were examined with both MR imaging and endoscopy or surgery. On a per patient basis, MR imaging had an overall sensitivity of 91% and a specificity of 71% for active disease. The Crohn's disease activity index had a sensitivity of 92% and a specificity of 28%. On a per segment basis, MR imaging had a sensitivity of 59% and a specificity of 93%. Bowel wall thickening of greater than 4 mm, bowel wall enhancement (ratio of signal intensity of abnormal to normal bowel > 1.3:1), and increased mesenteric vascularity were useful in identifying active disease. A layered enhancement pattern after the IV administration of gadolinium was highly specific for active inflammation. MR imaging is useful in assessing the activity of Crohn's disease and may be helpful when clinical scoring is equivocal.
    American Journal of Roentgenology 01/2002; 177(6):1325-32. DOI:10.2214/ajr.177.6.1771325 · 2.73 Impact Factor

  • Gastroenterology 04/2001; 120(5). DOI:10.1016/S0016-5085(08)81352-2 · 16.72 Impact Factor
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    ABSTRACT: To determine the sensitivity and specificity of computed tomography (CT) pneumocolon in the detection of colorectal neoplasms. A total of 201 consecutive patients with colorectal symptoms or requiring surveillance for colorectal neoplasms underwent both conventional colonoscopy and CT pneumocolon. On conventional colonoscopy 13 invasive colorectal carcinomas were detected in 13 patients, and 118 polyps in 63 patients (14 polyps were > or =1 cm in diameter, 25 were 6-9 mm, and 79 were < or =5 mm). CT pneumocolon detected all 13 cancers, two false positive cancers, but only 20 polyps (seven were > or =1 cm). This resulted in a sensitivity of 100% (95% confidence interval (CI) 87-100%) and specificity of 99% (95% CI 97-100%) for detection of invasive carcinoma, and a sensitivity of 73% (95% CI 56-90%) and specificity of 94% (95% CI 91-98%) for detection of invasive carcinoma and/or > or =1 cm polyps. CT pneumocolon also identified invasive carcinoma not seen at colonoscopy because of incomplete examination in three patients, and detected metastases in six colorectal carcinoma patients and extracolonic carcinoma in a further seven patients. CT pneumocolon had a high sensitivity and specificity for detection of invasive colorectal carcinoma but not colorectal polyps. CT pneumocolon may be suitable for initial investigation of patients with symptoms of colorectal malignancy.
    Gut 12/2000; 47(6):832-7. · 14.66 Impact Factor
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    International Journal of Gastrointestinal Cancer 06/1999; 25(3):229-250. DOI:10.1007/BF02925972
  • Z Amin · J Healy · R D Leach ·
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    ABSTRACT: A 47-year-old man presented with a 4 day history of severe right upper quadrant pain with no radia- tion to the back or shoulder. There was some asso- ciated nausea, but no signi¢cant past history. The patient was afebrile. On examination, there was tenderness below the right costal margin and towards the epigastrium. Blood tests showed a normal white cell count, electrolytes and amylase and no biochemical evidence of cholestasis. An initial ultrasound was reported as showing a nor- mal biliary tree and several tiny polyps in the gall- bladder, but no evidence of gallstones or acute cholecystitis. The patient was treated with analgesics but the painpersistedandafurtherultrasoundscanwasper- formed 4 days later. This showed no change in the gallbladder or biliary tree but a poorly de¢ned 96463 cm echogenic mass was now seen abutting the anterior abdominal wall and pushing the left lobe of liver and bowel loops inferiorly (Figure 1). This mass was of similar echogenicity to intraab- dominal fat but had a small cystic area within it. No increased vascularity was detected on colour Doppler imaging. CT of the abdomen was per- formed (Figure 2). The patient's pain improved and he had only mild discomfort 1 week after pre- sentation. A repeat CTwas performed1month later (Figure 3), by which time the patient's symptoms had completely resolved. What do the CTscans showandwhat is the diag- nosis?
    British Journal of Radiology 05/1999; 72(856):421-2. DOI:10.1259/bjr.72.856.10474510 · 2.03 Impact Factor

Publication Stats

1k Citations
229.94 Total Impact Points


  • 1993-2012
    • University College London
      Londinium, England, United Kingdom
  • 2011
    • University College London Hospitals NHS Foundation Trust
      • Department of Radiology
      Londinium, England, United Kingdom
    • University of Birmingham
      Birmingham, England, United Kingdom
  • 1999-2002
    • Chelsea and Westminster Hospital NHS Foundation Trust
      Londinium, England, United Kingdom
  • 1998
    • West Middlesex University Hospital NHS Trust
      TW9, England, United Kingdom
  • 1993-1996
    • Middlesex Hospital
      मिडलटाउन, Connecticut, United States