Remarkable reduction of exposure rate in patients with stress-only myocardial perfusion scan: let's safe mankind from unjustified radiation exposure

To measure radiation exposures rate in low-risk patients having stress-only and stress-rest myocardial perfusion imaging. This was a prospective study conducted from January 2012 till November 2012 upon patients with low pre-test probability for coronary artery disease [CAD]. A stress MPI [stress-only if MPI is normal and no resting study] followed by a resting MPI study [same day] if stress study was positive or equivocal. Exposure rates [in milli-Roentgen/hour, mR/hr] from injected patients at 1 meter distance were measured at 10 minutes, 1 hour and at time of releasing patients in both groups. Total 369 patients were included and 104 [28%] patients had stress-only and 265 [72%] had stress-resting studies. Mean administered [99m]Tc-MIBI dose in Stress-only and Stress-rest groups was 8 +/- 1 mCi and 24 +/- 03 mCi respectively [p<0.05]. Exposure rates[in mR/hr] within 10 min, 1 hour and at release time in Stress-only and stress-rest groups were 0.394, 0.294, 0.194and 1.540, 1.431, 1.207 respectively [p<0.05]. Mean stay of patients in laboratory was 90 +/- 39 minute in Stress-only and 156 +/- 53 minute in Stress-Rest group [p <0.0001]. There was a significantly widening gap between exposure rates from patients with Stress-only and stress-rest protocols as 26:74%, 21:79% and 16:84% at 10 min, 1 hour and at time of release respectively. We conclude that adopting a Stress-only MPI protocol in low risk patients ensures significantly lower radiation doses to patients and technologists. A worldwide paradigm shift in nuclear cardiology practice would safe mankind from unjustified radiation exposure

Assay for Molybdenum-99 breakthrough in PAKGEN, PINSTECH generators: a clinical audit at Akuh, Karachi

Molybdenum-99 breakthrough is a rare but potential cause of enormous and unjustified radiation exposure to patients and technologist in nuclear medicine. Recommended limit of [99] Mo in an eluate is 0.15 uCi of [99] Mo / mCi of [99m]Tc. The purpose of this clinical audit was to measure the Mo-99 concentration in eluate of PAKGEN [[99] Mo-[99m]Tc generator] before administering to patients as a part of Good Medical Practice [GMP]. This clinical audit was conducted at The Aga Khan University Hospital, Karachi from January to May 2012 and during this period we evaluated 44 [99] Mo-[99m] Tc generators [PAKGEN]. In 369 elutions during this audit period, we did not find any evidence of [99] Mo breakthrough. This clinical audit proves that PAKGEN generators supplied by IPD, PINSTECH, Islamabad had good performance and proved generally to be a reliable source of [99m] Tc-pertechnetate. The application was safe and fulfilled the requirements for good medical practice

[131]I-MIBG on diagnostic and therapeutic frontiers in extra-adrenal abdominal paragangliomas: a case report with mini review

Paraganglioma are tumors originating from paraganglial system and may be associated with parasympathetic [head, neck and anterior mediastinum tumors] or sympathetic [adrenal or extraadrenal or posterior mediastinal tumor] system. Majority of sympathetic paraganglioma and minority of parasympathetic tumor are functional and [131I or [132]I labeled MIBG [Meta Iodio Benzyl Guanidine] is a well established tool with good sensitivity and exceedingly high specificity. We are presenting a case report of a large extradrenal paraganglioma with extensive bony metastases and raised serum Chromogranin-A level. In this case [131]-MIBG was not only helpful in revealing the true burden of functional disease but also showed an overwhelming therapeutic response proven on post-therapy MIBG scan and normalization of serum Chromogranin-A level. This case report is followed by a mini-review about pathology, genetic mutation, diagnosis and treatment of focused on extraadrenal paragangliomas

Early bone scan imaging protocol: a pragmatic approach to maintain patients throughput in a busy Nuclear Medicine Section

Radionuclide bone scan are acquired 3-4 hours after Technetium-99m Methylene Diphosphonate [[99m] Tc MDP] injection to ensures a better contrast between bone and soft tissue. However, in a busy department with limited gamma cameras this imaging protocol is the limiting factor for reduced patient throughput. Compare the image quality of early [1.5 hr] and delayed [3 hr] acquired bone scans in same patients for image quality and lesion detection efficiency. This prospective study was conducted at Section of Nuclear Medicine, Department of Radiology, Aga Khan University Hospital, Karachi from 1st August 2011 till 15th September 2011. We recruited 12 patients [age range: 18-75 years] with a male: female ratio of 4:8, who were pain free, cooperative and mobile. [99m]Tc MDP was injected intravenously. Patients were asked to have at least 250 cc of water after every 15 minutes] and void urine frequently to minimize bladder dose. At 1.5 hour and 3 hour post-injection, whole body imaging were acquired under a double head, gamma camera [ECAM, Siemens, Germany] with same acquisition parameters for both images. These images were read by an experienced nuclear physician who evaluated the scans for over all image quality [subjective] and lesion detection efficiency [estimation of lesion appreciable on a scan]. The image quality of early [1.5 hr] and delayed scans were labeled as acceptable [fair bone to soft tissue contrast] and good [good bone to soft tissue contrast] respectively by the reader. Twenty three [23] lesions were identified on early scan and all of these lesions were appreciable on delayed studies as well and no discordance was identified. In a busy nuclear medicine section, to maintain patients' throughput, imaging at 1.5 hour may be used safely in those patients who are cooperative and mobile

Nephrotoxicity of CDDP assessed estimating glomerular filtration rate with 99mTc-DTPA plasma sample method

To assess early nephrotoxicity of CDDP [Cis-diamminedichloroplatinum] manifested by a decline in the glomerular filtration rate [GFR] estimated by plasma two sample clearance method [PSC 2] after 99mTc.DTPA injection. Descriptive study. Department of Nuclear Medicine, Karachi Institute of Radiotherapy and Nuclear Medicine, Karachi, from September 2004 to January 2005. The renal function was assessed on 36 patients suffering from different types of cancer and receiving CDDP in doses of >/= 50 mg/m[2] before and after in each of six CDDP cycles. The GFR was determined by PSC 2 method after 99mTc-DTPA injection]. A paired sample t-test was used for comparison of the mean value with significance at p < 0.01. There were [28 males and 8 females; age range being 16-68 years]. The average decline in GFR baseline to the end of sixth cycles was 43.86 ml/min/1.73m[2] [p=0.000] as estimated by PSC 2 method. There was a significant fall of average 9.36 ml/min/1.73m[2] [p <0.01] in GFR as observed in each cycle of CDDP estimated by the PSC 2 method. In the initial four cycles, CDDP produced a major nephrotoxic effect of average 10.27 ml/min/1.73m[2] [p <0.01] fall in GFR. This then gradually declined to a plateau of an average decline in GFR of 7.76 and 7.31 ml/min/1.73m[2] [p=0.000] after the 5[th] and 6[th] cycle respectively. CDDP produced an early nephrotoxicity which was manifested by a significant decline in GFR in each cycle. Tc-99m PSC 2 method for GFR estimation should be used periodically for the early detection of nephrotoxicity induced by CDDP

Diagnostic accuracy of Tc-99m-MIBI for breast carcinoma in correlation with mammography and sonography

To evaluate the accuracy of 99mTc-MIBI scintimammography [SMM] in differentiating malignant breast cancer from benign breast mass and in detecting axillary lymph node metastasis in comparison with mammography and ultrasonography. Comparative cross-sectional study. At the Karachi Institute of Radiotherapy and Nuclear Medicine [KIRAN], Karachi, from December 2006 to May 2007. A total of 28 patients [both with breast lumps or/and axillary masses] included were in the study. They underwent clinical examination, mammography and ultrasound imaging followed by planar SMM using a single head detector. All subjects received a 740-1110 MBq bolus injection of [99m]Tc-Sestamibi. 5-10 minutes and 1 hour delayed images were acquired after the injection. SMM scans were considered positive when there was focal area of increased radiotracer uptake. Qualitative [visual] as well as quantitative evaluation of scans was done and compared with ultrasound and mammography, taking histopathology as Gold standard. Sensitivity, specificity, negative and positive predictive values [NPV and PPV respectively] were determined. There were 22 patients presenting with breast lesions [20 palpable, 2 non-palpable] and 6 patients with axillary lump. Scintimammography accurately predicted malignant lesions in the breast [sensitivity 93.3%, specificity. 71.4%, PPV 87.5%, NPV 83.3%, overall accuracy 86.4%] as well as in patients with axillary metastasis [sensitivity 100%, specificity 66%, PPV 75%, NPV 100%, accuracy 83%]. A combination of scintimammography with any other imaging modality provides better results than a single test to detect breast cancer. SMM has good diagnostic accuracy in the detection of breast cancer as well as in axillary metastasis in association with mammography and ultrasound

Dual phase qualitative and quantitative 99mtc-mibi scinfimammography for predicting response to neoadjuvant chemotherapy in breast cancer

To determine the role of dual phase 99mTc-MIBI scintimammography in predicting chemotherapeutic response in breast cancer. Cross-sectional study. Karachi Institute of Radiology and Nuclear Medicine [KIRAN], from September 2004 to March 2005. Female patients with locally advanced breast cancer being planned for the anthracycline-based neoadjuvant chemotherapy were included in this study. All subjects received a 740 MBq bolus intravenous injection of 99mTc-MIBI. Ten minutes and 3 hours post-injection planar images were obtained in prone, lateral and supine positions using double head gamma camera. MIBI washout was scored as follows: > 30% as a positive prognostic test [predicting a poor response to chemotherapy] and < 30% as negative prognostic test [predicting a good response to chemotherapy]. Qualitative analysis of MIBI scans was also performed and categorized as visual wash-out or no visual washout as apparent on the early and delayed images. The criterion for the good and bad response was the reduction of > 50% and < 50% in the tumour burden respectively. Accuracy analysis, Chi-square test and Wilcoxan sign rank test were applied. There were 32 females [mean age: 46.3 years; median age 46 years; age range 33-65 years]. Quantitative dual phase 99mTc-MIBI scintimammography was found to be a good predictor of chemotherapeutic response in breast cancer. These were true positive in 8 patients and true negative in 19 patients with sensitivity [Sens.] 72%, specificity [Spec.] 90%, Positive Predictive Value [PPV] 80%, Negative Predictive Value [NPV] 86.5%, p < 0.03. Receiver Operating Characteristics [ROC] curve analysis demonstrates 30% as a cut-off value for the wash-out in quantitative dual phase MIBI for the prediction of the chemotherapeutic response. In comparison, qualitative scintimammography had Sens. 82%, Spec. 53%, PPV 29%, NPV 93% and p < 0.38. Statistical difference was found between early and delayed uptake ratios in the responders and non-responders. Quantitative dual phase 99mTc-MIBI scintimammography is a simple, reliable, non-invasive and effective tool for predicting the response to neoadjuvant chemotherapy. Furthermore, quantitative assessment is more precise than qualitative [visual wash-out] approach

Prediction of cardiac events in patients having left bundle-branch block with/without chest pain using dipyridamole technetium-99m-sestamibi myocardial perfusion imaging

To determine the prognostic value of myocardial perfusion scintigraphy with dipyridamole stress in patients with preexisting left bundle-branch block [LBBB] with or without chest pain. Seventy-six patients, mean age 53 +/- 10 years, with preexisting LBBB underwent technetium-99m-sestamibi perfusion imaging with dipyridamole infusion protocol [0.56 mg/kg]. Stress and rest single photon emission computed tomography [SPECT] images were interpreted by consensus of 2 experienced nuclear medicine physicians and classified as low-risk scans [normal myocardial perfusion scan, small reversible/small fixed defect] and high-risk scans [large, severe, fixed or reversible defect and dilated left ventricle cavity]. The patients were followed up for 24 +/- 8 months and occurrences of hard cardiac events [infarction or cardiac death] were noted. Of the 76 patients, 52 [68%] had low-risk scans and the remaining 24 [32%] had high-risk scans. In the low-risk group, 1 [1.9%] cardiac death and 2 [3.8%] cases of nonfatal myocardial infarction occurred, while in the high-risk group, 5 [20.8%] suffered cardiac death, and 3 [12.5%] nonfatal myocardial infarction. Overall survival rate was 98.1% in the low-risk group compared with 79.2% in the high-risk group with a significant difference of p = 0.034. Negative predictive value of normal myocardial perfusion scintigraphy for the occurrence of death was 100%. No significant difference in survival rate among patients with or without chest pain [p = 0.31] was observed. Myocardial perfusion imaging with dipyridamole provided important prognostic information in patients with LBBB; it was useful in stratifying the patients according to cardiovascular morbidity and mortality, and would thus allow the clinician to provide early treatment especially in the high-risk category

Isolated tuberculosis thyroiditis as solitary thyroid nodule

Isolated involvement of the thyroid by tuberculosis is very rare as reported in literature. We are presenting a case of isolated tuberculous thyroiditis presented as a solitary thyroid nodule. The patient was treated with anti-tuberculous regimen and he responded well with disappearance of the nodule and normalization of the thyroid scan

Estimation of glomerular filtration rate by using tc-99m DTPA plasma I sample method, Gates method, Cockcroft-Gault method and predicted creatinine clearance method: a prospective comparative analysis with plasma 2 - sample clearance method

To compare diagnostic accuracy of predicted clearance method, Gates method. Cockcroft-Gault method and plasma 1-sample clearance method with plasma 2-samples clearance method with Tc-99m DTPA for the estimation of glomerular filtration rate[GFR]. This study included 91 consecutive patients who were referred for evaluation of renal function to the Nuclear Medicine section of Karachi Institute of Radiotherapy and Nuclear Medicine [KIRAN] from September 2004 to September 2005. The GFR was determined simultaneously by 5 methods including Plasma two-Sample Clearance method after Tc-99m DTPA injection [PSC 2]; Plasma one-Sample Clearance method after Tc-99 m DTPA injection [PSC I]; Gamma camera uptake method after Tc-99m DTPA injection [Gates method]; Predicted Creatinine Clearance by Modification of Diet and Renal Diseases [MDRD]: and Cockeroft-Gault's equation for GFR estimation [CG]. PSC 2 was chosen as a reference, Out of the 91 patients, 71 were males and 20 females with age ranging from 16-68 years. The regression equation of the PSC 1, Gates, MDRD and CC method against the NC 2 was Y = 1.884+0.970X [r=0.90, p<0.001, SEE value-10, 23 ml/min/1.73m2]. Y = - 9.944 + l.083X [r=0.82, p<0.001, SEE valuel=11.02 mI/min/1.73m2], Y=25.606+0.640X [r=0.71, <0.002, SEEvaIuc=15.56 ml/min/1.73m2], and Y=14.9811-0.714X [r=0.77, p=0.002, SEE value=14.44 mI/min/1.73m2] respectively. In comparison with the GFR by PSC 2, the PSC I and Gates tended to overestimate by 1% [p=0.359] and 2% [p=0.265] respectively, MDRD and CC tended to underestimate GER by 11% and 14% respectively [p<0.001] PSC I correlate well with PSC 2 and either can be substituted for the other as ideal GFR markers. The Gates method shows good correlation with PSC 2 however it is less precise than PSC I. MDRD and CG methods due to significant underestimation are not considered as ideal GFR marker

[99m]Tc-nannocolloid localization of lymphorenal fistula causing chylurla

Chyluria is an abnormal condition in which chyle appears in the urine because of a fistulous communication between the lymphatics and the urinary tract. It is not life-threatening and spontaneous regression is reported in 50% of cases. Lymphangiography has been the main imaging modality for localization of the site of fistula, but it is invasive and requires expertise. Lymphoscintigraphy using Tc-99m labelled colloid is a safe, non-invasive, reproducible technique, which bears less radiation exposure. A 67-year-old male presented with 7-month history of chyluria following a spinal surgery. Bilateral lower limb lymphoscintigram revealed sluggish lymph flow in the left lower limb and visualization of tracer in the left kidney consistent with lymphorenal fistula. Subsequent cystography revealed appearance of chylous urine from left ureter. Patient refused surgery

Bone scan: a sensitive modality for diagnosing and predicting outcome for reflex sympathetic dystrophy

Reflex sympathetic dystrophy is a consequence of overactive sympathetic nervous system that results in burning pain, stiffness, swelling and discoloration of the affected limb. This case report describes the condition in a man that was diagnosed with the help of radionuclide bone scan

Sentinel lymph node scintigraphy and radioguided dissection in breast carcinoma: an initial experience at Aga Khan University Hospital

To evaluate the efficacy of SLN biopsy using imaging and gamma probe in breast cancer and to establish this technique at Aga Khan University Hospital. Thirty two patients [mean age 33-76 yrs] with operable breast carcinoma [4 with post-neo adjuvant therapy] with clinically negative axilla were studied. In 28 patients simultaneous axillary dissection was performed. Sentinel lymph nodes [SLN] scintigraphy was performed a day before surgery by injecting Tc-99m labeled nannocolloid sub-dermally in the peri-areolar region in 24 and peri-tumoral in remaining 8. First lymph node [LN] to appear to on the scan was labeled as SLN and marked on the skin. Blue dye was also injected in all patients and blue and hot LN was explored in the axilla using gamma probe. The sentinel LN was identified in 31 patients [96.9% success rate] while in one patient [3.1%] SLN was not visualized on the scan [negative study] and this was a post-neo-adjuvant therapy case. The blue dye successfully localized the sentinel LNs in all 32 cases The gamma probe guided localization was successful in all 31 while in one case with post-neo-adjuvant chemotherapy it failed. In 9 out of 32 [28.1%] cases SLN was positive for metastasis and in 6 out of these 9 [66.6%] the SLN was the only metastatic node. This includes the post-neo-adjuvant case as well. There was no case of skip metastasis, i.e. negative SNL and positive other axillary nodes. In remaining 23 [71.9%] cases SLN was negative for metastasis and in all, axilla was free of disease [NPV of 100%]. Lymphoscintigraphy with gamma probe guided SNL biopsy is safe, simple and highly reliable technique. With blue dye technique it reduces the blindness of the procedure if performed independently but increases the cost. Finally, this can accurately stage the axilla, possibly allowing axillary dissection to be foregone in patients where the SLN is clear