Nuclear Medicine Examinations Research Articles

Biliary Disorders, Anomalies, and Malignancies in Children.

Biliary abnormalities in children are uncommon, and the spectrum of biliary disorders is broader than in adult patients. Unlike in adults, biliary disorders in children are rarely neoplastic and are more commonly rhabdomyosarcoma rather than cholangiocarcinoma. Pediatric biliary disorders may be embryologic or congenital, such as anatomic gallbladder anomalies, anomalous pancreaticobiliary tracts, various cholestatic processes, congenital cystic lesions, or genetic conditions. They may also be benign, such as biliary filling anomalies, biliary motility disorders, and biliary inflammatory and infectious disorders. Distinguishing these entities with a single imaging modality is challenging. US is the primary imaging modality for initial evaluation of biliary abnormalities in children, due to its wide availability, lack of ionizing radiation, and low cost and because it requires no sedation. Other examinations such as MRI, CT, and nuclear medicine examinations may provide anatomic and functional information to narrow the diagnosis further. Hepatobiliary-specific contrast material with MRI can provide better assessment of biliary anatomy on delayed images than can traditional MRI contrast material. MR cholangiopancreatography (MRCP) allows visualization of the intra- and extrahepatic biliary ducts, which may not be possible with endoscopic retrograde cholangiopancreatography (ERCP). Suspected biliary atresia requires multiple modalities for diagnosis and timely treatment. Determining the type of choledochal cyst calls for a combination of initial US and MRCP. Many benign and malignant biliary masses require biopsy for definitive diagnosis. Knowledge of the imaging appearances of different pediatric biliary abnormalities is necessary for appropriate imaging workup, providing a diagnosis or differential diagnosis, and guiding appropriate management. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

[Preoperative Simulation in Epilepsy Surgery].

In patients with intractable epilepsy, seizure focus resection can yield favorable seizure outcomes. First, the localization of the seizure focus is estimated by noninvasive methods such as magnetic resonance imaging(MRI), video-electroencephalography(EEG)monitoring, nuclear medicine examinations, magnetoencephalography, and neuropsychological tests. A subgroup of patients may require additional information obtained from the intracranial EEG. There are two major methods for intracranial EEG: intracranial EEG with subdural grid electrodes(SDG)and stereotactic electroencephalography. If the estimated seizure focus overlaps with the eloquent area in noninvasive studies, the margin and extent of the resection are determined by the results of intracranial EEG and functional mapping by electrical cortical stimulation. Herein, we present a case of lobe epilepsy with subtle MRI lesions in the superior temporal sulcus of the language-dominant hemisphere. The results of the SDG and functional mapping showed that the seizure onset zone overlapped with the language area. Resection of the middle and inferior temporal gyri and multiple transections of the language area resulted in Engel IIB seizure outcomes. In such cases, a thorough preoperative simulation is required to determine the best resection margin for seizure control and functional preservation.

Nuclear medicine practice in Japan: a report of the ninth nationwide survey in 2022.

Subcommittee on Survey of Nuclear Medicine Practice in Japan has performed a nationwide survey of nuclear medicine practice every 5years since 1982 to survey contemporary nuclear medicine practice and its changes over the years. The subcommittee sent questionnaires, including the number and category of examinations as well as the kind of the radiopharmaceuticals during the 30days of June 2022 to all nuclear medicine institutes in Japan. The total numbers of them for the year 2022 were estimated depends on the 1-month data. A total of 1095 institutes responded to the survey, including 364 positron emission tomography (PET) centers. The recovery rate was 90.6%. The number of gamma cameras installed was 1299 in total, with 2.5% decrease in 5years. Dual-head cameras and hybrid SPECT/CT scanners accounted for 83.8% and 35.5%, respectively. The number of single-photon tracer studies in 2022 was 1.11million which means increase in 2.7% in 5years. Bone scintigraphy was a leading examination (31.0%), followed by myocardial scintigraphy (27.1%) and cerebral perfusion study (23.8%) in order. The percentage of SPECT studies showed an increase from 63.5% in previous survey to 66.8% in this survey. PET centers have also increased from 389 to 412, as compared with the previous one. One hundred and twenty-two PET centers have installed one or two in-house cyclotrons. Increasing trends of the PET studies were observed from 1992 to 2017, the trend changed and PET studies showed 1.5% decrease in 5years. 18F-FDG accounted for 98.6% (610,497 examinations). PET examinations using 11C-methionine, 13N-NH3 and 11C-PIB have decreased, with 1624, 2146 and 525 examinations, respectively in 2022. The total number of nuclear medicine examination was eventually increased by 1.0%. Therapies for pheochromocytoma or paraganglioma (PPGL) with 131I-MIBG and for neuroendocrine tumor with 177Lu-DOTA-TATE were newly started, however, a total number of targeted radionuclide therapy was decreased by 17.7% because 131I-radioiodine and 223Ra targeted therapies were decreased and supply of some radioisotopes was discontinued. 131I-radioiodine targeted therapy showed a decrease in 5years (- 15.9%), including 4099 patients for thyroid cancer. The number of out-patient thyroid bed ablation therapy with 1110MBq of 131I was also decreased to 1015 per year. The number of admission rooms specialized for radionuclide targeted therapy increased from 157 to 160. The number of 223Ra targeted therapies for castration-resistant metastatic prostate cancer (mCRPC) was 1041 patients. This survey was performed during COVID-19 pandemic, however, total number of nuclear medicine examinations was almost same as previous survey (+ 1.0%). Radionuclide therapies with 131I-MIBG and 177Lu-DOTA-TATE were newly started, and new radionuclide therapy will be available in future, therefore, the development of radionuclide therapy will be continued. We are convinced that this survey report is useful in understanding the current status of the nuclear medicine practice in Japan, and in devising the new strategy to strengthen a role ofnuclear medicine.

Conceptual design of the high-power electron beam irradiator using niobium-tin superconducting cavity

In recent years, there has been an increasing demand for high-intensity beams in the field of electron beam irradiation. This includes mass production of nuclear medicine examinations using 99Mo and high-efficiency production through material modification via material irradiation. Although superconducting cavities can achieve high-current beam acceleration, a compact accelerator is desirable for general-purpose irradiation beams. In this paper, we designed a practical 10 MeV, 50 mA high-current beam irradiator using a new Nb3Sn superconducting cavity.

Value of nuclide scintigraphy in the diagnosis and prognosis of cardiac amyloidosis.

Amyloidosis is a local or systemic disease caused by the deposition of misfolded proteins outside the cell, with rapid progression, and dire prognosis. Common types of cardiac amyloidosis are monoclonal immunoglobulin light chain amyloidosis (AL-CA) and transthyretin cardiac amyloidosis (ATTR-CA). Nuclear medicine examinations can be accurate, rapid, and non-invasive to help diagnose diseases and can effectively predict the prognosis of patients with CA. Technetium (99Tcm)-labeled bisphosphonate imaging has been included in the consensus of experts and has become the first-line imaging method for the diagnosis of ATTR-CA. 123I-metaiodoenzylguanidine (MIBG) as a norepinephrine analogue can effectively assess cardiac sympathetic innervation in patients with CA. Aβ- amyloid imaging agents such as 11C-pittsburgh compound B and 18F-flubetaben are expected to be new techniques for diagnosing AL-CA and incorporating them into cardiac staging systems for AL-CA patients in the future. New imaging agents such as 18F-NaF has been widely used in the diagnosis, treatment response monitoring, and prognosis assessment of CA. Summarizing the research value of nuclide imaging in CA may provide new ideas for clinical realization of early detection of CA and accurate assessment of disease prognosis.

[Neuroendocrine tumors of the pancreas].

Neuroendocrine tumors (NET) of the pancreas fall into the group of gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN). The assignment of imaging morphological criteria to this heterogeneous group of complex tumors is often difficult. Diagnostic ultrasound, computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography-CT (PET/CT) are available for the detection of pancreatic NET (also referred to as NEN) and for the diagnosis of spread and the search for metastases. In particular, nuclear medicine examination methods with somatostatin analogues are of high value, since they make tumors visible with high sensitivity via radioactively labeled receptor ligands. CT and MRI have high detection rates of pancreatic NET. Further developments, such as diffusion imaging, have further improved these traditional cross-sectional imaging diagnostics. However, nuclear medicine methods are an important component in detection and are superior to CT and MRI. It is important for the radiologist to be familiar with NET of the pancreas, as it is an important differential diagnosis-also with regard to prognosis-of other pancreatic lesions. Because NET are often hypervascularized, abiphasic examination technique after contrast administration is mandatory for cross-sectional imaging. PET/CT with somatostatin analogues should be performed for further diagnosis.

Use of ionizing radiation in a Norwegian cohort of children with congenital heart disease: imaging frequency and radiation dose for the Health Effects of Cardiac Fluoroscopy and Modern Radiotherapy in Pediatrics (HARMONIC) study

BackgroundThe European-funded Health Effects of Cardiac Fluoroscopy and Modern Radiotherapy in Pediatrics (HARMONIC) project is a multicenter cohort study assessing the long-term effects of ionizing radiation in patients with congenital heart disease. Knowledge is lacking regarding the use of ionizing radiation from sources other than cardiac catheterization in this cohort.ObjectiveThis study aims to assess imaging frequency and radiation dose (excluding cardiac catheterization) to patients from a single center participating in the Norwegian HARMONIC project.Materials and methodsBetween 2000 and 2020, we recruited 3,609 patients treated for congenital heart disease (age < 18 years), with 33,768 examinations categorized by modality and body region. Data were retrieved from the radiology information system. Effective doses were estimated using International Commission on Radiological Protection Publication 60 conversion factors, and the analysis was stratified into six age categories: newborn; 1 year, 5 years, 10 years, 15 years, and late adolescence.ResultsThe examination distribution was as follows: 91.0% conventional radiography, 4.0% computed tomography (CT), 3.6% diagnostic fluoroscopy, 1.2% nuclear medicine, and 0.3% noncardiac intervention. In the newborn to 15 years age categories, 4–12% had ≥ ten conventional radiography studies, 1–8% underwent CT, and 0.3–2.5% received nuclear medicine examinations. The median effective dose ranged from 0.008–0.02 mSv and from 0.76–3.47 mSv for thoracic conventional radiography and thoracic CT, respectively. The total effective dose burden from thoracic conventional radiography ranged between 28–65% of the dose burden from thoracic CT in various age categories (40% for all ages combined). The median effective dose for nuclear medicine lung perfusion was 0.6–0.86 mSv and for gastrointestinal fluoroscopy 0.17–0.27 mSv. Because of their low frequency, these procedures contributed less to the total effective dose than thoracic radiography.ConclusionThis study shows that CT made the largest contribution to the radiation dose from imaging (excluding cardiac intervention). However, although the dose per conventional radiograph was low, the large number of examinations resulted in a substantial total effective dose. Therefore, it is important to consider the frequency of conventional radiography while calculating cumulative dose for individuals. The findings of this study will help the HARMONIC project to improve risk assessment by minimizing the uncertainty associated with cumulative dose calculations.Graphical

Secondary Cancer Risk of Radiotherapy and Imaging Examination for Two Different Malignancies in One Patient

Purpose: Radiotherapy (RT), which is considered one of the critical treatments for cancer patients is also known as adjuvant therapy and palliative care, and can be attempted alone or concurrent with chemotherapy. Although RT reduces the risk of recurrence, the scattered dose may enhance the risk of secondary cancer induction; this is raising some challenges in clinical practice. To the best of our knowledge, few studies to date have assessed such effects of brain cancer adjuvant radiotherapy.&#x0D; Materials and Methods: We estimated the RT-induced risk of secondary cancer for a 45-year-old patient who had undergone radiotherapy of the head and pelvis with a 6 MV photon beam in 15 and 10 sessions, respectively. The absorbed dose by the thyroid, breast, eye lenses, region overlying ovaries, and parotids was measured using Thermoluminescent Dosimeters (TLD). Since the patient was scanned before radiotherapy, it was decided to calculate their risk as well. To evaluate the cancer risk, radiobiological models for Excess Absolute Risk (EAR), as well as Excess Relative Risk (ERR) published by the Committee on the Biological Effects of Ionizing Radiation (BEIR) in report VII, were implemented. This study thus aimed to estimate the Risk of Exposure-Induced Death (REID) and assess the radiation dose delivered to patients from Computed Tomography (CT) scans and common diagnostic nuclear medicine examinations.&#x0D; Results: The mean risk of secondary cancer for sensitive organs was calculated 3 years after radiotherapy. The highest estimated ERR was related to the region overlying right and left ovaries for pelvic radiotherapy (47.82) and (51.17), and the next highest EAR followed by right and left eye lenses for brain radiotherapy (18.09) and (15.43), respectively. In addition, other cancers arising from CT scans had the highest REID values for solid cancer (0.0015) and bone scans revealed the highest REID values for other cancers (0.00121).&#x0D; Conclusion: Calculating the corresponding risks of RT is of great significance for the patients in procedural change. Choosing proper field sizes and adapted techniques to avoid excessive doses to healthy organs can thus be a great assistance in this regard.

Feasibility of using counts-per-volume approach with a new SPECT phantom to optimize the relationship between administered dose and acquisition time

We developed a phantom for single-photon emission computed tomography (SPECT), with the objective of assessing image quality to optimize administered dose and acquisition time. We investigated whether the concept of counts-per-volume (CPV), which is used as a predictor of visual image quality in positron emission tomography, can be used to estimate the acquisition time required for each SPECT image. QIRE phantoms for the head (QIRE-h) and torso (QIRE-t) were developed to measure four physical indicators of image quality in a single scan: uniformity, contrast of both hot and defective lesions with respect to the background, and linearity between radioactivity concentration and count density. The target organ's CPV (TCPV), sharpness index (SI), and contrast-to-noise ratio (CNR) were measured for QIRE-h and QIRE-t phantoms, and for anthropomorphic brain and torso phantoms. The SPECT image quality of the four phantoms was visually assessed on a 5-point scale. The acquisition time and TCPV were correlated for all four phantoms. The SI and CNR values were nearly identical for the QIRE and anthropomorphic phantoms with comparable TCPV. The agreement between the visual scores of QIRE-h and brain phantoms, as well as QIRE-t and torso phantoms, was moderate and substantial, respectively. Comparison of SPECT image quality between QIRE and anthropomorphic phantoms revealed close agreement in terms of physical indicators and visual assessments. Therefore, the TCPV concept can also be applied to SPECT images of QIRE phantoms, and optimization of imaging parameters for nuclear medicine examinations may be possible using QIRE phantoms alone.

Assessment of radiation exposure in a nuclear medicine department of an oncology hospital

BackgroundMedical personnel in nuclear medicine departments are exposed to ionizing radiation which is associated with cancer induction and mortality risks. Examples of such personnel are those working in the hot-areas where radioisotopes for nuclear medicine examinations are prepared. This work aims to estimate the occupational radiation exposure for workers at the Nuclear Medicine department in Da Nang Oncology Hospital, Vietnam. Materials and methodsThe study was conducted from 2020 to 2021. The personal dose equivalents (Hp) were quantified for soft tissues for deep dose (Hp(10)), eye lens dose (Hp(3)), skin dose (and Hp(0.07)) were quantified utilizing optically stimulated luminescence dosimeters (OSLD) crystals. In this study, the dose equivalent at the hot area is measured by 9 OSLD, while that for staff was measured using 16 OSLD. ResultsIn 2020, the annual average Hp(10) was (0.38 mSv ± 1.39); in 2021 Hp(10) was (0.25 mSv ± 1.27). The average Hp(10) was well below the annual occupational dose limits (20 mSv.year−1). Regarding the annual dose, all recorded values were quite low compared to the annual radiation dose limits for radiation staff (20 mSv annual ∼ 1.67 mSv.month−1). Nevertheless, some points of measurement revealed a high-value dose of 5.69 mSv ± 2.83. This suggests that rigorous evaluation of the workplace is essential to ensuring workers' exposure is kept within safe levels. ConclusionsIt is concluded that the Hp(10) and Hp(0.07) for the working environment and radiation workers were below the dose limits from ICRP. In addition, it is recommended that continuous monitoring of the occupational dose in nuclear medicine department is essential to reduce the dosimetric hazards of personnel working in the department.

Applying Implementation Science Principles to Systematize High-Quality Care for Potentially Significant Imaging Findings

ObjectiveUse principles of implementation science to improve the diagnosis and management of potentially significant imaging findings. MethodsMultidisciplinary stakeholders codified the diagnosis and management of potentially significant imaging findings in eight organs and created a finding tracking management system that was embedded in radiologist workflows and IT systems. Radiologists were trained to use this system. An automated finding tracking management system was created to support consistent high-quality care through care pathway visualizations, increased awareness of specific findings in the electronic medical record, templated notifications, and creation of an electronic safety net. Primary outcome was the rate of quality reviews related to eight targeted imaging findings. Secondary outcome was radiologist use of the finding tracking management tool. ResultsIn the 4 years after implementation, the tool was used to track findings in 7,843 patients who received 10,015 ultrasound, CT, MRI, x-ray, and nuclear medicine examinations that were interpreted by all 34 radiologists. Use of the tool lead to a decrease in related quality reviews (from 8.0% to 0.0%, P < .007). Use of the system increased from 1.7% of examinations in the early implementation phase to 3.1% (+82%, P < .00001) in the postimplementation phase. Each radiologist used the tool on an average of 294.6 unique examinations (SD 404.8). Overall, radiologists currently use the tool approximately 4,000 times per year. DiscussionRadiologists frequently used a finding tracking management system to ensure effective communication and raise awareness of the importance of recommended future follow-up studies. Use of this system was associated with a decrease in the rate of quality review requests in this domain.

Trends in the development of nuclear medicine in the Russian Federation for 2015–2020

The federal forms of statistical reporting (3-DOZ form , form No. 30 of the Ministry of Health of the Russian Federation and radiation-hygienic passports of the subjects of the Russian Federation for 2015–2020) were analyzed in order to estimate the current status of nuclear medicine and assess the perspective and developing proposals for improving the national system of radiation protection in nuclear medicine . Over the past six years , the number of radionuclide examinations in the Russian Federation has been at the same level : on average 530 thousand per year . In 2020 the number of examinations decreased that was caused by the epidemic of coronavirus infection . The largest number of examinations in 2015-2020 were performed in Moscow (21%) and St. Petersburg (11%). Federal medical centers equipped with high-tech equipment are located in these cities , and patients from different regions are examined in these centers . The examination of bone is the most common examination in Russia: 40% from all of nuclear medicine examination ; there is a moderate increase of that examinations . There is a high number of renal examinations (17%). The next most frequent are examinations of myocardium , thyroid , liver and lungs ; the number of these examinations are decrease . Due to the development of modern diagnostic technologies , installation of new positron emission tomography departments and replacement of the old equipment with the new one ( decrease in the number of renographs and increase the number of positron emission tomographs ), the number of “ other ” examinations are increased with a factor of 3.7 since 2015 but the number of “ functional ” examinations is decreased . About two thousand studies per year were examined on a scanner ( renograph , gamma camera , single-photon emission tomography ), and about 0.6 thousand hybrid imaging examinations per year were performed on a single-photon emission tomography combined with computed tomography . The annual collective dose of radionuclide diagnosis in the country has increased from 1.2 to 3.7 thousand man-Sv since 2015. The main contribution to the collective dose in Russia was associated with “ other ” examinations , which include hybrid imaging and whole body positron emission tomography : 55% (39% in St. Petersburg , 60% in Moscow). Due to the limitations and heterogeneous content of the federal forms of statistical reporting it is difficult to assess the current state of nuclear medicine in the Russian Federation. The authors of the study were updated of the data collection system in the radionuclide diagnosis in 3-DOZ forms ; it is under approval . For detailed and reliable assessment of the nuclear medicine in the country , it is necessary to conduct a separate survey to determine the types of nuclear medicine examinations , the gender and age profile of patients and patient doses . That survey should be conducted in St. Petersburg or Moscow, as model subjects of the Russian Federation.

Report on the Regional Workshop on Image Reading Conducted by the Japanese Society of Nuclear Cardiology.

Since 2007, The Japanese Society of Nuclear Cardiology (JSNC) has been conducting regional training workshops on film reading for physicians and technologists who are just beginning their career in cardiac nuclear medicine examinations. JSNC will continue this workshop to expand the fields of cardiac nuclear medicine examinations.

[Impact of Residual Radioactivity Rate of 99mTc-macro Aggregated Albumin (MAA) in Syringes and Administration Routes with a Focus on Pediatric Nuclear Medicine Examinations].

The purpose of this study was to evaluate the residual radioactivity in the syringe and route of administration of a low fluid volume 99mTc-macro aggregated albumin (MAA) intended for pediatric nuclear medicine examinations. We evaluated the residual characteristics, as the effect of elapsed time from drawing up of radiopharmaceuticals to plastic syringe to administration, and the effect of volume of 99mTcO4- solution to be labeled, the effect of rinsed times of plastic syringe, effect of dose of calculated by consensus guidelines for pediatric nuclear medicine and residual location in injection sets with 99mTc-MAA. Residual radioactivity was measured using planar images obtained by the gamma camera. Residual radioactivity rate of 99mTc-MAA, 99mTc-MAG3, 123I-IMP showed 41.3±1.6%, 14.4±0.6%, 14.6±2.0%, respectively. 99mTc-MAA clearly showed a higher residual rate. Residual radioactivity rate increased with the extension of the elapsed time, and reached a high value of 41.3% in 30 minutes. Residual radioactivity rate was dependent on the different volume of 99mTcO4- to be labeled (4.0 ml and 8.0 ml). Residual radioactivity rate did not change when the number of rinsed was more than one. Residual rate was around 40% at all doses of calculated by consensus guidelines for pediatric nuclear medicine. 99mTc-MAA showed the highest residual radioactivity rate among radiopharmaceuticals used in pediatric nuclear medicine examinations. The factor that most affected the residual radioactivity rate of 99mTc-MAA was the elapsed time from draw up to the plastic syringe to administration.

Are We Adequately Communicating the Potential Radiation Risks to Patients Undergoing Nuclear Medicine Examinations? A Clinical Audit

Are We Adequately Communicating the Potential Radiation Risks to Patients Undergoing Nuclear Medicine Examinations? A Clinical Audit

Assessment of Radiation Exposure Dose for Nuclear Medicine Workers from 18F-FDG, 99mTc MDP, and 99mTc.

Nuclear medicine or diagnostic radiology personnel are always exposed to low-level radiation from radionuclides used in medical diagnostics, which lead to potential biological hazards or effects. External exposure for workers in two nuclear medicine centers was measured by recruiting 120 patients. Three nuclear medicine examinations were performed using F18-FDG PET/CT,99mTc- MDP bones scan, and 99mTc thyroid scan by a digital radiation dosimeter. The average received accumulative radiation dose for workers was found to be 0.838±0.17, 0.527±0.11, and 0.270±0.05 µSv for F18-FDG PET/CT, 99mTc-MDP bones scan, and 99mTc thyroid scan, respectively. The annual effective dose for workers was estimated to be 2.09±0.42, 1.34±0.27, and 0.68±0.14 mSv, respectively. Moreover, the average patient-to-staff dose coefficients were found to be 0.024±0.005, 0.003±0.001, and 0.007±0.002 µSv m2/MBq h for F18- FDG PET/CT, 99mTc-MDP bones scan, and 99mTc thyroid scan, respectively. It is clear from the results that the radiation doses received by workers during the nuclear medicine imaging examinations were less than the doses recommended by the International Commission on Radiological Protection (ICRP) for such examinations.

Oncology and cardiology positron emission tomography/computed tomography faced with COVID-19: A review of available literature data.

The COVID-19 pandemic has forced people to significantly change their lifestyles and attitudes, and has greatly burdened healthcare delivery systems worldwide. The redistribution of the medical delivery system to maintain normal medical care while responding generously to COVID-19 is a continuing challenge that weighs heavily on medical institutions. Among imaging modalities, chest X-rays and computed tomography (CT) examinations have clearly made a large contribution to treatment of COVID-19. In contrast, it is difficult to express the standpoint of nuclear medicine examinations in a straightforward manner, as the greatest emphasis in this modality has been on how necessary medical care can continue to be provided. Many clinical reports of nuclear medicine examinations related to COVID-19 have been published, and knowledge continues to accumulate. This review provides a summary of the current state of oncology and cardiology positron emission tomography (PET) examinations related to COVID-19, and includes preparation of the nuclear medicine department, trends in PET examinations, specific imaging findings on 18F-fluorodeoxyglucose (FDG) PET/CT, imaging of complications of COVID-19, PET tracers other than FDG, and the effects of vaccines on PET imaging findings.

Analysis of “visible in retrospect” to monitor false-negative findings in radiological reports

PurposeFalse-negative findings in radiological reports can lead to serious adverse patient outcomes. We determined the frequency and tendency of false-negative findings in radiological reports by searching for words related to “visible in retrospect”.MethodsIn the period of 34 months, we extracted radiological reports containing words related to “visible in retrospect”. Of these reports, we extracted false-negative findings that were not described in past reports and were first detected retrospectively. Misinterpretations were excluded. The occurrences of the terms that we identified were analyzed by all examinations, modality, month, and anatomical and lesion classifications were analyzed.ResultsOf the 135,251 examinations, 941 reports (0.71%) with 962 findings were detected, with an average of 1.4 findings per business day. By modality, 713 of 81,899 (0.87%) CT examinations, 208 of 36,174 (0.57%) MR, 34 of 9,585 (0.35%) FDG-PET-CT, 2 of 2,258 (0.09%) digital radiography, and 5 of 5,335 (0.09%) other nuclear medicine examinations were found. By anatomical classification, there were 383 (40%) in chest, 353 (37%) in abdomen, 162 (17%) in head, 42 (4.4%) in face and neck, 9 (0.93%) in extremity, and 13 (1.4%) in others. By lesion classification, we identified 665 (69%) for localized lesion, 170 (18%) for vascular lesion, 83 (8.6%) for inflammatory lesion, 14 (1.5%) for traumatic lesion, 12 (1.2%) for organ dysfunction, 11 (1.1%) for degenerative lesion, and 7 (0.7%) for the others. Notable high-frequency specific site diseases by modality were 210 (22%) of localized lesions in lung on CT.ConclusionOur results demonstrated that missed lung localized lesions on CT, which account for about a fifth of false-negative findings, were the most common false-negative finding.

Assessment and Registration of Effective Doses Used in Diagnostic Nuclear Medicine Examinations

Over the recent period, the Russian healthcare system has been undertaking a nation-wide renewal of equipment for nuclear medicine, which, in turn, opens a gate to new diagnostic radiopharmaceuticals (DRPs) to routine practice. The market welcomed a new class of targeted DRPs. Dozens of PET centres and diagnostic rooms where DRPs with ultrashort-lived radionuclides are used for medical examination have been put into operation. All this dictates the need to modify the existing guidelines that govern this area. In 2021, there was an update in the procedural guidelines (PGs) MU 2.6.1.3700-21 “Assessment and registration of effective doses used in diagnostic nuclear medicine examinations”. The document presented the dose coefficients for new DRPs based on the latest data from the International Commission on Radiological Protection and the literature. This included calculation of the effective doses (using tissue weighting factors) from 1 MBq of radioactivity for approximately 280 DRPs used across five different age groups, as per ICRP Publication 60. These PGs apply to diagnostic nuclear medicine examinations performed using DRPs, scintigraphy, single-photon emission computed tomography (SPECT) and positron emission tomography (PET) alone or in combination with X-ray computed tomography (SPECT/CT; PET/CT). The guidelines do not apply to radionuclide therapies that involve DRP administration that require individual planning and assessment of the absorbed doses across the target regions, critical organs and other radiosensitive organs and tissues.

High &lt;sup&gt;11&lt;/sup&gt;C-methionine uptake in brain abscess: radiological, metabolic and morphological findings: a case report

An increased amino acid metabolism is characteristic for many brain malignancies. Combined positron emission and computed tomography (PET/CT) with radiolabeled amino acids is often used in recognizing the tumor nature of the structural brain lesion detected on MRI. On 11C-methionine PET/CT a hallmark of a brain tumor is an increased amino acid uptake, topographically coinciding with a structural lesion on MRI. However, high 11C-methionine uptake in the brain lesion is not tumor specific and could be seen in a number of non-tumor diseases. The paper presents three observations of a brain abscess, radiological and metabolic data of which in MRI and 11C-methionine PET/CT simulated a malignant cerebral tumor. The reasons for patients seeking nuclear medicine examination were seizures or focal neurological symptoms, as well as a suspicion of a cerebral tumor based on the contrast-enhanced MRI. Knowledge of the non-tumor disease characterized by high 11C-methionine uptake will help avoid misdiagnosis of a cerebral tumor.